Special Issue "Green Separation and Extraction Processes"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Green Processes".

Deadline for manuscript submissions: 31 December 2020.

Special Issue Editors

Prof. Dr. Kostas A. Matis
Website SciProfiles
Guest Editor
Laboratory of Chemical and Environmental Technology, Department of Chemistry, Aristotle University, GR-541 24 Thessaloniki, Greece
Interests: separation science and technology (flotation); wastewater treatment; environmental biotechnology; inorganic materials; mineral processing
Special Issues and Collections in MDPI journals
Dr. George Z. Kyzas
Website SciProfiles
Guest Editor
Department of Chemistry, International Hellenic University, Kavala 65404, Greece
Interests: wastewater treatment; polymers; decontamination; materials; sorption; nanobubbles; transportation phenomena
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The concept of unit operations over time and subsequent concepts in chemical technology has evolved into a unified field of separation processes and sustainability in this field (and its significance for the chemical and process industry) is of particular interest, not only scientifically, as, for example, the need for fresh sources of drinking water is becoming urgent worldwide. We certainly need the traditional raw materials in many everyday products, and for our computers, among other uses. Generally, the idea in the present issue – also according to the green chemistry principles – is to design processes to maximize the amount of raw materials in products, while being environmentally safe and energy efficient, and avoiding waste production. It should be noted that two contrasting perspectives have been adopted in the area: one states that continued extraction of non-renewable resources is a necessary part of sustainable development, whilst the other states that extraction of these resources must be greatly reduced or even eliminated. Green technologies are environmentally friendly operations that limit the negative impacts of traditional industrial activities and can contribute to addressing the challenge of sustainable management.

There has been much talk, from various perspectives (including even political), about going green. The explosion in the number of recent relevant publications may be explained by this heightened interest. For instance: ionic liquids were used in the extraction of phenolic compounds from bio-oils. Ionic liquids, also termed “green” and “designer” solvents, were proposed as promising solvents for diverse applications, including metal extraction. The economic aspect of the recovery of useful valuable minerals or metals, contributing to recycling meanwhile with environmental technology constitutes the focus of various applications. Microfluidics offered a continuous nanoparticle separation approach. Green thin-film nanocomposite membranes showed enhanced separation properties, thanks to the additional pores or channels offered by these nanomaterials for water purification. An ultrasound-assisted catalytic transesterification process was developed for biodiesel (which is greener compared to petroleum diesel and renewable) production. A number of technologies for the conversion of lignocelluloses into gas, liquid, and solid fuels, as well as platform chemicals, are being researched (i.e., for the production of green diesel and gasoline).

Green environmentally friendly adsorbents from agro-food wastes were also synthesized and tested – i.e., for the treatment of pharmaceutical effluents. Green synthesis of amino-functionalized carbon nanotube-graphene hybrid aerogels was prepared for high-performance heavy metal ion removal. Membranes based on functionalized ionic liquids also attracted attention for CO2 (which mainly comes from flue gas, natural gas, and syngas) separation. Various guidance tools and practices have been proposed to improve the sustainability of mining activity, while maintaining the economic viability. Tightening environmental regulations and increasing awareness for the need to protect ecosystems have effectively resulted in an increased interest in the alternative use of biosurfactants. There has been phenomenal progress in flotation chemistry and chemicals – both in design and manufacture; there are also many new concepts and tools that can be capitalized. The above brief introduction justifies the importance of this Special Issue.

Prof. Dr. Kostas A. Matis
Prof. Dr. George Z. Kyzas
Guest editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Please note that for papers submitted after 31 December 2020 an APC of 2000 CHF applies. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • separation
  • extraction
  • sustainability
  • green chemistry

Published Papers (64 papers)

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Editorial

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Open AccessEditorial
Green Separation and Extraction Processes: Part I
Processes 2020, 8(3), 374; https://doi.org/10.3390/pr8030374 - 23 Mar 2020
Abstract
Supercritical fluid extraction comprises a known technology applied to obtain volatile compounds from flowers, i [...] Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)

Research

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Open AccessArticle
Optimization of Extrusion and Ultrasound-Assisted Extraction of Phenolic Compounds from Jizi439 Black Wheat Bran
Processes 2020, 8(9), 1153; https://doi.org/10.3390/pr8091153 - 15 Sep 2020
Abstract
Jizi439, a newly developed black wheat breeding line, was reported to effectively regulate blood glucose, which may potentially be associated with its intrinsic high level of phenolic compounds (PCs). To maximize the PCs yield and thereby enhance their antioxidant activity, orthogonal experiments were [...] Read more.
Jizi439, a newly developed black wheat breeding line, was reported to effectively regulate blood glucose, which may potentially be associated with its intrinsic high level of phenolic compounds (PCs). To maximize the PCs yield and thereby enhance their antioxidant activity, orthogonal experiments were designed in sequence for extrusion of Jizi439 black wheat bran (BWB) powder and followed by the extraction of PCs assisted with ultrasound technique. White wheat bran was used as a control. The optimum condition for extrusion was 110 °C, 25% feed water content, 140 rpm screw speed; meanwhile, 50 °C, 40 min, 35 kHz ultrasonic frequency, 300 W ultrasonic power for ultrasound-assisted extraction (UAE). Total phenolic content (TPC) as determined by Folin–Ciocalteu method was 2856.3 ± 57.7 μg gallic acid equivalents (GAE) per gram of dry weight (DW) of phenolic extract; meanwhile, antioxidant activity (AA) in terms of DPPH radical scavenging ratio was 85.5% ± 1.1% under optimized conditions, which were both significantly higher than the control. Phenolic acids except for gallic acid, as well as flavonoids, including luteolin and apigenin were increased by extrusion and ultrasound, as suggested by HPLC results. In conclusion, our study would provide a valuable reference for processing Jizi439 BWB before making or commercially utilize it into health-related food products. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Eucalyptus camaldulensis, Citrus aurantium, and Citrus sinensis Essential Oils as Antifungal Activity against Aspergillus flavus, Aspergillus niger, Aspergillus terreus, and Fusarium culmorum
Processes 2020, 8(8), 1003; https://doi.org/10.3390/pr8081003 - 18 Aug 2020
Abstract
Several molds are able to colonize wood and many building products or solid wood causing losses for their valuable uses. Essential oils (EOs) from aromatic plants can be used as an ecofriendly biofungicide against the growth of several molds. EOs from Eucalyptus camaldulensis [...] Read more.
Several molds are able to colonize wood and many building products or solid wood causing losses for their valuable uses. Essential oils (EOs) from aromatic plants can be used as an ecofriendly biofungicide against the growth of several molds. EOs from Eucalyptus camaldulensis, Citrus aurantium, and C. sinensis have a broad-spectrum antimicrobial activity. EOs from of E. camaldulensis air-dried aerial parts, C. aurantium leaf and C. sinensis peel, and their combinations (1:1 v/v) were evaluated for their antifungal activity against the growth of four common mold fungi (Aspergillus flavus, A. niger, A. terreus, and Fusarium culmorum). The chemical compositions of the EOs were analyzed with GC/MS. The main compounds in EO from E. camaldulensis were spathulenol (20.84%), eucalyptol (12.01%), and sabinene (9.73%); in C. aurantium were linalyl acetate (42.29%), and linalool (29.76%); and in C. sinensis were D-limonene (73.4%) and γ-terpinene (22.6%). At 50 µL/mL, C. sinensis EO showed the highest fungal mycilial growth inhibition (FMGI) percentage (86.66%) against A. flavus. C. sinensis, E. camaldulensis, and E. camaldulensis/C. sinensis showed FMGI values of 96%, 91.66%, and 75.66% respectively, against A. niger. EOs from C. aurantium and C. sinensis showed potent activity against A. terreus (100% FMGI), while C. aurantium/E. camaldulensis and E. camaldulensis/C. sinensis showed FMGI values of 74.33% and 70.66%, respectively. Potent activity against F. culmorum with 100% was observed as the application of E. camaldulensis and C. sinensis EOs at 50 µL/mL, while E. camaldulensis/C. sinensis (50 µL/mL) showed FMGI value of 65.66%. The results suggest using the EOs and their combinations from E.camaldulensis, C. aurantium, and C. sinensis as a biofungicide against molds. The potent properties of EOs offer the possibility of using them as eco-friendly, safe, and cost-effective antimicrobials for molds that could cause discoloration of the wood packaging or food spoilage. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Process Optimization for Green Synthesis of Silver Nanoparticles Using Indonesian Medicinal Plant Extracts
Processes 2020, 8(8), 998; https://doi.org/10.3390/pr8080998 - 17 Aug 2020
Abstract
Silver nanoparticles (AgNPs) are an interesting metal nanoparticle that can be incorporated into pharmaceutical products, including for diabetic foot ulcers as an antimicrobial agent. Green synthesis of AgNPs using plant extracts has been drawing much attention as it is simple, eco-friendly, stable, and [...] Read more.
Silver nanoparticles (AgNPs) are an interesting metal nanoparticle that can be incorporated into pharmaceutical products, including for diabetic foot ulcers as an antimicrobial agent. Green synthesis of AgNPs using plant extracts has been drawing much attention as it is simple, eco-friendly, stable, and cost-effective. This present study was performed to evaluate the potential of three Indonesian medicinal plant extracts, namely Phyllanthus niruri (PN), Orthosiphon stamineus (OS), and Curcuma longa (CL), as reducing and capping agents in the green synthesis of AgNPs, and to optimize their concentrations. Based on the yields and characteristics of the formed nanoparticles, which were analyzed using a UV-Vis spectrophotometer, particle size analyzer, scanning electron microscope, and X-ray diffractometer, Phyllanthus niruri extract at a concentration of 0.5% was concluded as the best extract in the green synthesis of AgNPs. It is thereby a prospective reducing and capping agent for further scale-up studies. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Analysis and Prediction of Influencing Parameters on the Coal Classification Performance of a Novel Three Products Hydrocyclone Screen (TPHS) Based on Grey System Theory
Processes 2020, 8(8), 974; https://doi.org/10.3390/pr8080974 - 12 Aug 2020
Abstract
A novel hydrocyclone including a cylindrical screen embedded in a conventional hydrocyclone (CH), named three products hydrocyclone screen (TPHS), has been successfully designed. In TPHS, the combination of centrifugal classification and screening was employed to separate particles. In this paper, Grey theory, as [...] Read more.
A novel hydrocyclone including a cylindrical screen embedded in a conventional hydrocyclone (CH), named three products hydrocyclone screen (TPHS), has been successfully designed. In TPHS, the combination of centrifugal classification and screening was employed to separate particles. In this paper, Grey theory, as an effective means to the laws of both complex and uncertainty system’s behavior with small samples, was used to investigate the operational (feed concentration and feed pressure) and structural (aperture size, spigot diameter, and vortex finder diameter) parameters on performance evaluation Hancock classification efficiency (HE), imperfection (I), and cut size (d50c). The experiments of coal sample (0–1 mm) show that TPHS with coarser particles in underflow exhibited the absent “fish-hook”. The closeness calculated using the Grey System algorithm indicates that the performance of TPHS was closely related to the operation and structure parameters. Further, the order of grey incidence degree between different parameters and HE (or I or d50c) is the spigot diameter and aperture size with the highest value, the feed pressure and vortex finder diameter with the middle value, and the feed concentration with the lowest value. The prediction using the GM(1, N) algorithm implies that the dynamic prediction model for the performance evaluation can be created depending on the operation, structure and previous performance value. The mean relative errors between the predicted and actual HE, I, and d50 were 2.84%, 5.83%, and 3.57%, respectively, which exhibit the accurate prediction. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Extraction of Phosphorous from a Phosphorous-Containing Vanadium Titano-Magnetite Tailings by Direct Flotation
Processes 2020, 8(7), 874; https://doi.org/10.3390/pr8070874 - 20 Jul 2020
Cited by 1
Abstract
In this study, there is 1.42% P2O5 in the P-containing V-Ti magnetite tailings in Miyi Region of China, with the valuable minerals mainly including apatite, and aluminosilicate minerals as the main gangue components. The direction flotation process was used to [...] Read more.
In this study, there is 1.42% P2O5 in the P-containing V-Ti magnetite tailings in Miyi Region of China, with the valuable minerals mainly including apatite, and aluminosilicate minerals as the main gangue components. The direction flotation process was used to recover phosphorous from the low-grade phosphorous-bearing V-Ti magnetite tailings. The results showed that an optimized phosphorous concentrate with a P2O5 grade of 31.35% and P2O5 recovery of 88.02% was obtained by flotation process of one roughing, three scavengings, and three cleanings under roughing conditions, which employed pulp pH of 9, grinding fineness of <0.039 mm occupying 90%, flotation concentration of 25%, and dosages of carboxymethylcellulose, oxidized paraffin wax soap, and pine oil of 400 g/t, 300 g/t, and 20 g/t, respectively. Optimized one scavenging, two scavenging, and three scavenging conditions used a pulp pH of 9, and dosages of carboxymethylcellulose, oxidized paraffin wax soap, and pine oil of 200 g/t, 150 g/t, 10 g/t; 100 g/t, 75 g/t, and 5 g/t; and 100 g/t, 75 g/t, and 5 g/t, respectively. Optimized one cleaning, two cleaning, and three cleaning condition dosages of carboxymethylcellulose of 100 g/t, 50 g/t, and 25 g/t, respectively. Study of analysis and characterization of phosphorous concentrate by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) show that most gangue minerals enter the flotation tailings, the main minerals in phosphorous concentrate are apatite, olivine, and feldspar. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Organoboron Ionic Liquids as Extractants for Distillation Process of Binary Ethanol + Water Mixtures
Processes 2020, 8(5), 628; https://doi.org/10.3390/pr8050628 - 24 May 2020
Abstract
Aminoethers of boric acid, which are organoboron ionic liquids, were synthesized by using boric acid, triethanolamine, and triethylene glycol/diethylene glycol. Due to the formation of intermolecular complexes of borates, the structure of aminoethers of boric acid contains ion pairs separated in space, giving [...] Read more.
Aminoethers of boric acid, which are organoboron ionic liquids, were synthesized by using boric acid, triethanolamine, and triethylene glycol/diethylene glycol. Due to the formation of intermolecular complexes of borates, the structure of aminoethers of boric acid contains ion pairs separated in space, giving these compounds the properties inherent to ionic liquids. It is established that the thermal stability of aminoethers under normal atmospheric conditions increases with an increase in the size of the glycol. According to measurements of fast scanning calorimetry, density, dynamic viscosity, and electrical conductivity, water is involved in the structural organization of aminoethers of boric acid. The impact of the most thermostable organoboron ionic liquids on the phase equilibrium conditions of the vapor–liquid azeotropic ethanol–water mixture is studied. It is shown that the presence of these substances leads to increase in the relative volatility of ethanol. In general, the magnitude of this effect is at the level shown by imidazole ionic liquids, which provide high selectivity in the separation of aqueous alcohol solutions. A large separation factor, high resistance to thermal oxidative degradation processes, accompanied by low cost start reagents, make aminoethers of boric acid on the basis of triethylene glycol a potentially effective extractant for the extractive distillation of water–alcohol mixtures. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Deacidification of Palm Oil Using Betaine Monohydrate-Carboxylic Acid Deep Eutectic Solvents: Combined Extraction and Simple Solvent Recovery
Processes 2020, 8(5), 543; https://doi.org/10.3390/pr8050543 - 07 May 2020
Abstract
Steam stripping is commonly used to remove free fatty acids from crude palm oil. An alternative deacidification method, solvent extraction performed at a much lower temperature, would preserve the natural antioxidants in the refined palm oil. In this work, palmitic acid was extracted [...] Read more.
Steam stripping is commonly used to remove free fatty acids from crude palm oil. An alternative deacidification method, solvent extraction performed at a much lower temperature, would preserve the natural antioxidants in the refined palm oil. In this work, palmitic acid was extracted using betaine monohydrate-propionic acid and betaine monohydrate-acetic acid deep eutectic solvents (DESs). The effect of temperature (40 °C to 80 °C), mass ratio of palm oil to solvent (2:1 to 1:2), and palmitic acid content in the palm oil feed (2% to 8% mass) on the distribution coefficient values of palmitic acid (0.44–0.93) was investigated. For the first time, a facile recovery of DESs could be accomplished by a cooling process where up to 98% of the palmitic acid separates as solid. A solvent extraction process for palm oil deacidification, employing a DES with a distribution coefficient value much higher than unity, will provide advantages over the steam stripping process. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Bioactivity of Selected Phenolic Acids and Hexane Extracts from Bougainvilla spectabilis and Citharexylum spinosum on the Growth of Pectobacterium carotovorum and Dickeya solani Bacteria: An Opportunity to Save the Environment
Processes 2020, 8(4), 482; https://doi.org/10.3390/pr8040482 - 21 Apr 2020
Cited by 1
Abstract
Phenolic acids and natural extracts, as ecofriendly environmental agents, can be used as bio bactericides against the growth of plant pathogenic bacteria. In this study, isolation trails from infected potato tubers and stems that showed soft rot symptoms in fields revealed two soft [...] Read more.
Phenolic acids and natural extracts, as ecofriendly environmental agents, can be used as bio bactericides against the growth of plant pathogenic bacteria. In this study, isolation trails from infected potato tubers and stems that showed soft rot symptoms in fields revealed two soft rot bacterial isolates and were initially identified through morphological, physiological, and pathogenicity tests. The molecular characterization of these isolates via PCR, based on the 16S rRNA region, was carried out by an analysis of the DNA sequence via BLAST and Genbank, and showed that the soft rot bacterial isolates belong to Pectobacterium carotovorum subsp. carotovorum (PCC1) and Dickeya solani (Ds1). The in vitro results of the tested phenolic acids against the cultured bacterial isolates proved that concentrations of 800, 1600, and 3200 μg/mL were the most effective. Ferulic acid was the potent suppressive phenolic acid tested against the Ds1 isolate, with an inhibition zone ranging from 6.00 to 25.75 mm at different concentrations (25–3200 μg/mL), but had no effect until reaching a concentration of 100 μg/mL in the PCC1 isolate, followed by tannic acid, which ranged from 7.00 to 25.50 mm. On the other hand, tannic acid resulted in a significant decrease in the growth rate of the PCC1 isolate with a mean of 9.11 mm. Chlorogenic acid was not as effective as the rest of the phenolic acids compared with the control. The n-hexane oily extract (HeOE) from Bougainvillea spectabilis bark showed the highest activity against PCC1 and Ds1, with inhibition zone values of 12 and 12.33 mm, respectively, at a concentration of 4000 μg/mL; while the HeOE from Citharexylum spinosum wood showed less activity. In the GC/MS analysis, nonanal, an oily liquid compound, was found ata percentage of 38.28%, followed by cis-2-nonenal (9.75%), which are the main compounds in B. spectabilis bark HeOE, and 2-undecenal (22.39%), trans-2-decenal (18.74%), and oleic acid (10.85%) were found, which are the main compounds in C. spinosum wood HeOE. In conclusion, the phenolic acids and plant HeOEs seem to raise the resistance of potato plants, improving their defense mechanisms against soft rot bacterial pathogens. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Recovering Scandium from Scandium Rough Concentrate Using Roasting-Hydrolysis-Leaching Process
Processes 2020, 8(3), 365; https://doi.org/10.3390/pr8030365 - 22 Mar 2020
Cited by 4
Abstract
In this study, a roasting-hydrolysis-acid leaching process is used to extract scandium from the scandium rough concentrate. The scandium rough concentrate containing Sc2O3 of 76.98 g/t was obtained by magnetic separation, gravity separation, and electric separation from Sc-bearing Vi-Ti magnetite [...] Read more.
In this study, a roasting-hydrolysis-acid leaching process is used to extract scandium from the scandium rough concentrate. The scandium rough concentrate containing Sc2O3 of 76.98 g/t was obtained by magnetic separation, gravity separation, and electric separation from Sc-bearing Vi-Ti magnetite tailings in the Panxi area of China. The majority of scandium in scandium rough concentrate mainly occurs in diopside, titanopyroxene, montmorillonite, chlorite, talc, aluminosilicate minerals, and isomorphism. Sodium salt and scandium coarse concentrate are added into the roasting furnace for roasting, which makes the fusion reaction of silicon, aluminum and sodium salt to produce soluble salts such as sodium silicate and sodium metaaluminate. Scandium is further recovered from the hydrolysis residue by acid leaching. Test results show scandium leaching recovery of 95.12% and the acid leaching residue with Sc2O3 content of 8.12 g/t are obtained, while the extraction of scandium is obvious. There is no obvious peak value of Scandium spectrum in hydrochloric acid leach residue. Most of scandium in hydrolytic residue is dissolved into Sc3+ and enters into the liquid phase. The main minerals in leach residue are perovskite, ferric silicate, and olivine. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Phytochemical Compounds of Branches from P. halepensis Oily Liquid Extract and S. terebinthifolius Essential Oil and Their Potential Antifungal Activity
Processes 2020, 8(3), 330; https://doi.org/10.3390/pr8030330 - 11 Mar 2020
Cited by 5
Abstract
In the present study, the antifungal activity of wood treated with Pinus halepensis branch n-hexane oily liquid extract (OLE) and Schinus terebinthifolius branch essential oil (EO) was evaluated against the growth of four phytopathogenic fungi—Bipolaris oryzae, Fusarium oxysporum, Fusarium solani, [...] Read more.
In the present study, the antifungal activity of wood treated with Pinus halepensis branch n-hexane oily liquid extract (OLE) and Schinus terebinthifolius branch essential oil (EO) was evaluated against the growth of four phytopathogenic fungi—Bipolaris oryzae, Fusarium oxysporum, Fusarium solani, and Rhizoctonia solani. Air-dried wood samples of Pinus roxburghii were autoclaved, and each wood received 100 µL of the concentrated oils from P. halepensis and S. terebinthifolius. The main compounds identified in S. terebinthifolius branch EO were terpinen-4-ol (18.25%), cis-β-terpineol (15.60%), γ-terpinene (12.46%), sabinene (9.83%), α-terpinene (8.56%), and 4-thujanol (6.71%), while the main compounds in P. halepensis branch HeO were 2-undecenal (22.25%), 4-hydroxy-10-methyl-3,4,7,8,9,10-hexahydro-2H-oxecin-2-one (8.43%), (Z)-2-decenal (6.88%), nonanal (5.85%), (2E)-2-decenal (4.65%), (E,E)-2,4-decadienal (4.41%), arachidonic acid methyl ester (4.36%), and 2-(7-heptadecynyloxy)tetrahydro-2H-pyran (4.22%). P. halepensis OLE at a concentration of 3% showed the highest inhibition percentage of fungal growth (IPFG) of B. oryzae, followed by S. terebinthifolius EO at 3% and 2%, with IPFG values of 80%, 74.44%, and 71.66%, respectively. At a concentration of 3%, branch oils from S. terebinthifolius and P. halepensis were found to have the highest IPFG values with 45.55% and 40.55%, respectively, against F. oxysporum growth. Moderate to weak activity was found against F. solani when S. terebinthifolius EO and P. halepensis OLE were applied to wood. EO and OLE-treated wood samples at 3% produced inhibitions of 54.44% and 41.11%, respectively, against R. solani. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Mass Spectroscopic Analysis, MNDO Quantum Chemical Studies and Antifungal Activity of Essential and Recovered Oil Constituents of Lemon-Scented Gum against Three Common Molds
Processes 2020, 8(3), 275; https://doi.org/10.3390/pr8030275 - 27 Feb 2020
Cited by 6
Abstract
The present study described the possibility of using wood-treated oil-fungicide of lemon-scented gum (Corymbia citriodora) from newly emerged leaves and unripened fruits against the infestation of Fusarium culmorum, Rhizoctonia solani and Penicillium chrysogenum. Air-dried wood samples of Melia azedarach [...] Read more.
The present study described the possibility of using wood-treated oil-fungicide of lemon-scented gum (Corymbia citriodora) from newly emerged leaves and unripened fruits against the infestation of Fusarium culmorum, Rhizoctonia solani and Penicillium chrysogenum. Air-dried wood samples of Melia azedarach were treated with the extracted oils from leaves and unripened fruits from C. citriodora. The main chemical constituents identified in the essential oil (EO) from leaves were citronellal (55.31%), citronellol (21.03%) and isopulegol (10.79%), while in unripened fruits were α-pinene (17.86%), eudesmol (13.9%), limonene (9.19%), γ-terpinen (8.21%), and guaiol (7.88%). For recovered oils (ROs), the major components from leaves were D-limonene (70.23%), γ-terpinene (13.58%), β-pinene (2.40%) and isopregol (2.23%), while, 4-terpineol (21.35%), cis-β-terpineol, (19.33%), D-limonene (14.75%), and γ-terpinene (7.42%) represented the main components in fruits. EOs from leaves and fruits at the amounts of 100, 50 and 25 µL showed the highest inhibition percentage (IP) of 100% against F. culmorum and P. chrysogenum compared to control treatment, while at the amounts of 100, and 50 µL showed 100% IP of R. solani. Wood treated with ROs from leaves and fruits showed IPs of 96.66% and 93.33%, respectively, against the growth of R. solani. The mass spectra of the main components of C. citriodora leaves and fruits’ EOs have been recorded in electron ionization mode at 70 eV and fragmentation has been reported and discussed. On the other hand, different quantum parameters such as the heat of formation, ionization energy total energy, binding energy, electronic energy and dipole moment using the modified neglect of diatomic overlap (MNDO) semi-empirical method have been calculated. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Process Parameters Optimization of Gallic Acid Removal from Water by MIEX Resin Based on Response Surface Methodology
Processes 2020, 8(3), 273; https://doi.org/10.3390/pr8030273 - 27 Feb 2020
Cited by 1
Abstract
In this work, the response surface methodology was used to optimize the process parameters of gallic acid adsorption on magnetic ion exchange (MIEX) resin. Based on Box-Behnken Design, a quadratic polynomial model equation including solution pH, gallic acid concentration, MIEX resin dosage and [...] Read more.
In this work, the response surface methodology was used to optimize the process parameters of gallic acid adsorption on magnetic ion exchange (MIEX) resin. Based on Box-Behnken Design, a quadratic polynomial model equation including solution pH, gallic acid concentration, MIEX resin dosage and adsorption time was established. The reliability of the established regression equation was tested by variance analysis. Based on the regression equation, the technical parameters for gallic acid adsorption on MIEX resin were optimized and the effects of interaction between variables on the removal of gallic acid were analyzed. The results showed that the established regression equation was reliable and could effectively predict the removal of gallic acid. The optimal technical parameters were determined to be a pH of 9.17, a gallic acid concentration of 8.07 mg/L, a resin dosage of 0.98 mL/L and an adsorption time of 46.43 min. The removal efficiency of gallic acid was 97.93% under the optimal parameters. The interaction between pH and adsorption time had the most significant effect on the removal of gallic acid. The results of this study demonstrated that MIEX resin can remove gallic acid efficiently and relatively quickly under the condition of optimal technical parameters. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Extraction of Cobalt and Iron from Refractory Co-Bearing Sulfur Concentrate
Processes 2020, 8(2), 200; https://doi.org/10.3390/pr8020200 - 06 Feb 2020
Cited by 6
Abstract
In this study, oxidizing roasting, segregation roasting, and magnetic separation are used to extract cobalt and iron from refractory Co-bearing sulfur concentrate. The Co-bearing sulfur concentrate containing 0.68% Co, 33.26% Fe, and 36.58% S was obtained from V-Ti magnetite in the Panxi area [...] Read more.
In this study, oxidizing roasting, segregation roasting, and magnetic separation are used to extract cobalt and iron from refractory Co-bearing sulfur concentrate. The Co-bearing sulfur concentrate containing 0.68% Co, 33.26% Fe, and 36.58% S was obtained from V-Ti magnetite in the Panxi area of China by flotation. Cobalt pyrite and linneite were the Co-bearing minerals, and the gangue minerals were mica, chlorite, feldspar, and calcite in Co-bearing sulfur concentrate. The results show that cobalt is transformed from Co-pyrite and linneite to a Co2FeO4-dominated new cobalt mineral phase, and iron is transformed from pyrite to Fe2O3 and an Fe3O4-dominated new iron mineral phase after oxidizing roasting. Cobalt changed from CoFe2O4 to a new cobalt mineral phase dominated by [Co] Fe solid solution, and iron changed from Fe2O3 to a new iron mineral phase dominated by metal Fe and Fe3O4 after segregation roasting. Cobalt concentrate with a cobalt grade of 15.15%, iron content of 71.22%, and cobalt recovery of 90.81% as well as iron concentrate with iron grade of 60.06%, cobalt content of 0.11%, and iron recovery of 76.23% are obtained. The main minerals in the cobalt concentrate are Fe, [Co]Fe, Fe3O4, and SiO2, and the main minerals in the iron concentrate are Fe3O4, FeO, Ca2Si2O4, and Ca2Al2O4. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
The Potential Antibacterial and Antifungal Activities of Wood Treated with Withania somnifera Fruit Extract, and the Phenolic, Caffeine, and Flavonoid Composition of the Extract According to HPLC
Processes 2020, 8(1), 113; https://doi.org/10.3390/pr8010113 - 16 Jan 2020
Cited by 9
Abstract
In the present study, Melia azedarach wood blocks treated with different acetone extract concentrations from Withania somnifera fruits are assessed for their antibacterial and anti-fungal activities. Wood blocks of M. azedarach treated with W. somnifera fruit extract at concentrations of 0, 1, 2, [...] Read more.
In the present study, Melia azedarach wood blocks treated with different acetone extract concentrations from Withania somnifera fruits are assessed for their antibacterial and anti-fungal activities. Wood blocks of M. azedarach treated with W. somnifera fruit extract at concentrations of 0, 1, 2, and 3% are evaluated for in vitro antimicrobial activity against five genbank accessioned bacterial strains—Agrobacterium tumefaciens, Dickeya solani, Erwinia amylovora, Pseudomonas cichorii, and Serratia pylumthica—and two fungi, namely, Fusarium culmorum and Rhizoctonia solani. Through HPLC analysis we find that the most abundant quantified phenolic and flavonoid compounds of acetone extract (mg/100 g) are salicylic acid (9.49), vanillic acid (4.78), rutin (4702.58), and myricetin (1386.62). Wood treated with the extract at 2% and 3% show no growth of A. tumefaciens, E. amylovora, and P. cichorii. Use of the extract at 3% causes inhibition of fungal mycelia of F. culmorum and R. solani by 84.07% and 67.03%, respectively. In conclusion, potent antifungal and antibacterial activity against plant pathogens is found when an acetone extract of W. somnifera fruits is applied to wood samples. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
The Biofungicide Activity of Some Plant Essential Oils for the Cleaner Production of Model Linen Fibers Similar to Those Used in Ancient Egyptian Mummification
Processes 2020, 8(1), 79; https://doi.org/10.3390/pr8010079 - 07 Jan 2020
Cited by 6
Abstract
In this work, the essential oils (EOs) from Eriocephalus africanus leaf, Vitex agnus-castus leaf and fruit, Cymbopogon citratus leaf, and Rosmarinus officinalis leaf were used as antifungal agents against isolated Aspergillus flavus, Cladosporium cladosporioides, and Penicillium chrysogenum from an ancient Egyptian [...] Read more.
In this work, the essential oils (EOs) from Eriocephalus africanus leaf, Vitex agnus-castus leaf and fruit, Cymbopogon citratus leaf, and Rosmarinus officinalis leaf were used as antifungal agents against isolated Aspergillus flavus, Cladosporium cladosporioides, and Penicillium chrysogenum from an ancient Egyptian child’s mummy. The isolated fungi were used to colonize the samples of linen fibers. The best oil was used as a novel natural product for the cleaner production of model linen fibers similar to those used in ancient Egyptian mummification. Standard and original linen fibers were compared with the infected Linen samples using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses. The FTIR revealed the changes in the molecular structure of the cellulose, hemicellulose, and lignin of the infected linen fibers. The cellulose crystallinity indices decreased to 64.61%, 52.69%, and 54.63% in the linen inoculated with A. flavus, C. cladosporioides, and P. chrysogenum compared to the control sample (72.08%), thereby affecting the chemical properties of the cellulose. The mycelia inhibition percentages of the three fungi reached 100% after the leaf EO from V. agnus-castus was applied, followed by C. citratus. The V. agnus-castus leaf EO applied at contraptions of 250, 500, 50, 1000, and 2000 µL/mL showed 100% inhibition for A. flavus and P. chrysogenum and reached 100% against C. cladosporioides at concentrations of 500, 750, 1000, and 2000 µL/mL. C. citratus leaf essential oil applied at concentrations of 500, 750, 1000, and 2000 µL/mL showed 100% inhibition to the growth of A. flavus and C. cladosporioides and reached 100% inhibition against the growth of P. chrysogenum at concentrations of 750, 1000 and 2000 µL/mL. This inhibition could be related to the main compounds of caryophyllene (23.13%), eucalyptol (20.59%), sabinene (β-thujene) (12.2%), γ-elemene (9%), and β-farnesene (6.14%) identified in V. agnus-castus leaf EO or due to the main compounds of β-citral (43.63%) and geranial (41.51%), as identified in the leaf EO of C. citratus by GC/MS. The morphological changes in the hyphae of the fungi were observed via SEM examination, where V. agnus-castus leaf EO, the best active oil, showed potent inhibition to fungi grown on the model linen fiber. In this way, the morphology and the structure of the hyphae were effectively changed. Our findings prove that the designed model linen fiber treated with V. agnus-castus leaf EO is able to preserve wrapping fibres and represents a novel natural alternative for effective fungicidal treatment. Full article
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Open AccessArticle
Elevated Bioactivity of Ruta graveolens against Cancer Cells and Microbes Using Seaweeds
Processes 2020, 8(1), 75; https://doi.org/10.3390/pr8010075 - 06 Jan 2020
Cited by 5
Abstract
Human cancer and pathogenic microbes cause a significant number of deaths every year. Modulating current sources of natural products that control such diseases becomes essential. Natural algae, such as Ascophyllum nodosum and Ecklonia maxima, can modulate the metabolic processes as well the bioactivities [...] Read more.
Human cancer and pathogenic microbes cause a significant number of deaths every year. Modulating current sources of natural products that control such diseases becomes essential. Natural algae, such as Ascophyllum nodosum and Ecklonia maxima, can modulate the metabolic processes as well the bioactivities of Ruta graveolens L. The R. graveolens plants were subjected to nine soil drenches of A. nodosum (7 mL L−1), E. maxima (7 mL L−1), or both extracts. Morphological performance, gas exchange parameters, and essential oils (EOs) composition (GC-MS) were studied and the bioactivity was assessed against several cancer cells and pathogenic bacteria or fungi. Treatment with A. nodosum + E. maxima seaweed extracts (SWE) led to the highest morphological performance and gas exchange parameters. The highest antiproliferative, apoptotic, and caspase-3/7 activities of EO were against HeLa in SWE mixture treated plants. The best EO antimicrobial activities were obtained against Staphylococcus aureus and Penicillium ochrochloron. SWE mixtures treated plants showed the best bioactivities against microbes and cancer cells. The highest abundance of 2-undecanone (62%) and 2-nonanone (18%) was found in plants treated with SWE mixtures and caused the best anticancer and antimicrobial effects. Seaweed mixtures act as natural elicitors of pharmaceutical industries and favored 2-undecanone and 2-nonanone in R. graveolens. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Assessment of the Use of Natural Extracted Dyes and Pancreatin Enzyme for Dyeing of Four Natural Textiles: HPLC Analysis of Phytochemicals
Processes 2020, 8(1), 59; https://doi.org/10.3390/pr8010059 - 02 Jan 2020
Cited by 5
Abstract
In the present study, four natural textiles (cotton, linen, wool, and silk) were dyed with 14 naturally extracted dyes, and pancreatin enzyme was used in the dyeing process. The effects of pancreatin enzyme and its buffer on naturally dyed textile samples were evaluated. [...] Read more.
In the present study, four natural textiles (cotton, linen, wool, and silk) were dyed with 14 naturally extracted dyes, and pancreatin enzyme was used in the dyeing process. The effects of pancreatin enzyme and its buffer on naturally dyed textile samples were evaluated. Two concentrations of pancreatin enzyme and buffer were used as pretreatments for dyed textiles. Proteinic fabrics showed the highest relative color strength (RCS) values of 137.23% and 132.2% when the pancreatin enzyme was applied on wool and silk dyed with pomegranate skin and bloodroot at concentrations A and B, respectively. Linen fiber dyed with catechu tree showed the highest total color difference (TCD) values with buffer (6.83) and pancreatin enzyme A (5.7) and B (6.3). This shows that there were no side effects of the pancreatin enzyme on the studied dyed textiles. By high-performance liquid chromatography (HPLC) analysis, the root extract from madder showed the presence of salicylic acid (1758.91 mg/kg extract), quercetin (844.23 mg/kg extract), ellagic acid (784.86 mg/kg extract) and benzoic acid (582.68 mg/kg extract) as main compounds. In cochineal extract the main compounds were rutin (37.732 mg/kg extract), kampherol (1915.98 mg/kg extract), myricetin (809.97 mg/kg extract), quercetin (496.76 mg/kg extract) and salicylic acid (193.87 mg/kg extract). Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Toxicological Activity of Some Plant Essential Oils Against Tribolium castaneum and Culex pipiens Larvae
Processes 2019, 7(12), 933; https://doi.org/10.3390/pr7120933 - 07 Dec 2019
Cited by 5
Abstract
In the present work, essential oils (EOs) from Schinus terebinthifolius (ripe and unripe fruits and leaves), Origanum majorana (air-dried aerial parts), and Psidium guajava (leaves) were assayed for their insecticidal activity against red flour beetle (Tribolium castaneum) and Culex mosquito larvae [...] Read more.
In the present work, essential oils (EOs) from Schinus terebinthifolius (ripe and unripe fruits and leaves), Origanum majorana (air-dried aerial parts), and Psidium guajava (leaves) were assayed for their insecticidal activity against red flour beetle (Tribolium castaneum) and Culex mosquito larvae (Culex pipiens). Several components were identified in the EOs using Gas chromatography–mass spectrometry (GC/MS), of which Δ-3-carene (25.9%), γ-terpinene (19.4), and γ-elemene (7.1%) were the major ones in S. terebinthifolius ripe fruits, α-pinene (48.9%), germacrene D (12.9%), and α-thujene (7.7%) in S. terebinthifolius unripe fruits, γ-elemene (11.7%), spathulenol (10.1%), β-elemene (9.2%), and p-cymene (9.1%) in S. terebinthifolius leaves, α-pinene (25.5%), (E)-caryophyllene (15.7%), (E)-nerolidol (16.7%), and cedran-8-ol (8.8%) in P. guajava leaves, and terpinen-4-ol (21.7%), γ-terpinene (16.5%), and sabinene (10.1%) in O. majorana air-dried aerial parts. The lethal concentration (LC50) was calculated for tested EOs at different time periods (after 6, 12, 24, 48, and 72 h). After 6 h of treatment, the LC50 was 33.3 and 6.8 µg/L air for S. terebinthifolius ripe and unripe fruits, respectively, and >40 µg/L air for EOs of S. terebinthifolius leaves, O. majoranaair-dried aerial parts, and P. guajava leaves. After 24 h of treatment, the LC50 was 4.2, <2, 5, >40, and 6.1 µg/L air for EOs of S. terebinthifolius ripe fruits and leaves, O. majorana leaves, and P. guajava leaves, respectively. On the other hand, the LC50 values decreased when the exposed period was increased to 72 h, and were <2 µg/L air for EOs of S. terebinthifolius ripe fruits, unripe fruits, and leaves along with P. guajava leaves, respectively, and 37.912 for EO of O. majorana leaves. The LC50 value after 24 h of exposure of S. terebinthifolius unripe fruit EO was under 2 µg/L air, which means that the EO of S. terebinthifolius ripe fruit had a strong effect on adult T. castaneum adults compared to other tested EOs using the fumigation method. The present data confirm that the EOs of O. majorana leaves and S. terebinthifolius unripe fruits and leaves were more effective as larvicide than the EOs of S. terebinthifolius ripe fruits and P. guajava leaves on C. pipiens at a higher concentration (100 mg/L) when applied by the dipping method. EOs from S. terebinthifolius unripe or ripe fruits and leaves and P. guajava leaves were more effective as adulticide than EO of O. majorana leaves against T. castaneum when applied by the fumigant method. Full article
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Open AccessArticle
Assessment of the Toxicity of Natural Oils from Mentha piperita, Pinus roxburghii, and Rosa spp. Against Three Stored Product Insects
Processes 2019, 7(11), 861; https://doi.org/10.3390/pr7110861 - 18 Nov 2019
Cited by 3
Abstract
Three natural oils extracted from Mentha piperita, Pinus roxburghii, and Rosa spp. were assessed in order to determine their insecticidal activity against the adults of three stored product insects: the rice weevil (Sitophilus oryzae L.), the lesser grain borer ( [...] Read more.
Three natural oils extracted from Mentha piperita, Pinus roxburghii, and Rosa spp. were assessed in order to determine their insecticidal activity against the adults of three stored product insects: the rice weevil (Sitophilus oryzae L.), the lesser grain borer (Rhyzopertha dominica, Fabricius), and the red flour beetle (Tribolium castaneum, Herbst.). By Gas chromatography–mass spectrometry (GC/MS) analysis, the main compounds in the n-hexane oil from Rosa spp. were determined to be methyl eugenol (52.17%), phenylethyl alcohol (29.92%), diphenyl ether (7.75%), and geraniol (5.72%); in the essential oil from M. piperita, they were menthone (20.18%), 1,8-cineole (15.48%), menthyl acetate (13.13%), caryophyllene (4.82%), β-pinene (4.37%), and D-limonene (2.81%); and from the foliage of P. roxburghii, they were longifolene (19.52%), caryophyllene (9.45%), Δ-3-carene (7.01%), α-terpineol (6.75%), and γ-elemene (3.88%). S. oryzae and R. dominica were reared using sterilized wheat grains, and T. castaneum was reared on wheat flour mixed with yeast (10:1, w/w), all under laboratory conditions (27 ± 1 °C and 65% ± 5% Relative humidity (R.H). Two toxicity bioassays were used, as well as contact using thin film residues and fumigation bioassays. The results indicated that M. piperita caused a high toxicity for S. oryzae compared to other insects. High significant variations were observed between the tested M. piperita doses against the stored insects, and this natural material could be used to control insects that infect the grains. Also, the data indicated that the Rosa spp. oil had a low-toxicity effect against these insects compared to other oils. We recommend using natural oils against the stored weevils and petals, rather than the chemical agent, so as to serve human health. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
Open AccessArticle
Effects of Processing Conditions on the Simultaneous Extraction and Distribution of Oil and Protein from Almond Flour
Processes 2019, 7(11), 844; https://doi.org/10.3390/pr7110844 - 11 Nov 2019
Cited by 1
Abstract
The enzyme-assisted aqueous extraction process (EAEP) is an environmentally friendly strategy that simultaneously extracts oil and protein from several food matrices. The aim of this study was to investigate the effects of pH (6.5–9.5), temperature (45–55 °C), solids-to-liquid ratio (SLR) (1:12–1:8), and amount [...] Read more.
The enzyme-assisted aqueous extraction process (EAEP) is an environmentally friendly strategy that simultaneously extracts oil and protein from several food matrices. The aim of this study was to investigate the effects of pH (6.5–9.5), temperature (45–55 °C), solids-to-liquid ratio (SLR) (1:12–1:8), and amount of enzyme (0.5–1.0%) on the extraction and separation of oil and protein from almond flour using a fractional factorial design. Oil and protein extraction yields from 61 to 75% and 64 to 79% were achieved, respectively. Experimental conditions resulting in higher extractability were subsequently replicated for validation of the observed effects. Oil and protein extraction yields of 75 and 72% were achieved under optimized extraction conditions (pH 9.0, 50 °C, 1:10 SLR, 0.5% (w/w) of enzyme, 60 min). Although the use of enzyme during the extraction did not lead to significant increase in extraction yields, it did impact the extracted protein functionality. The use of enzyme and alkaline pH (9.0) during the extraction resulted in the production of more soluble peptides at low pH (5.0), highlighting possible uses of the EAEP skim protein in food applications involving acidic pH. The implications of the use of enzyme during the extraction regarding the de-emulsification of the EAEP cream warrant further investigation. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Essential and Recovery Oils from Matricaria chamomilla Flowers as Environmentally Friendly Fungicides Against Four Fungi Isolated from Cultural Heritage Objects
Processes 2019, 7(11), 809; https://doi.org/10.3390/pr7110809 - 04 Nov 2019
Cited by 6
Abstract
Recovery oils, obtained from the hydro-distillation of the fresh flowers of Matricaria chamomilla, as well as essential oils, were studied for their environmental purposes in cultural heritage. These oils were assayed for their antifungal activity against the growth of four molds isolated [...] Read more.
Recovery oils, obtained from the hydro-distillation of the fresh flowers of Matricaria chamomilla, as well as essential oils, were studied for their environmental purposes in cultural heritage. These oils were assayed for their antifungal activity against the growth of four molds isolated from archaeological manuscripts (Aspergillus niger), museum gypsum board Antique (A. flavus), museum archaeological tissue (A. terreus), and museum organic materials (Fusarium culmorum) of cultural heritage objects. Oils were applied to inhibit the growth of fungi at amounts of 25, 50, 75 and, 100 µL/mL, and compared with negative controls (0 µL/mL) or positive controls (Sertaconazol 3g/L). Using GC/MS analysis, the main chemical compounds identified in the essential oil were (Z)-β-farnesene (27%), D-limonene (15.25%), and α-bisabolol oxide A (14.9%), while the compounds identified in the recovery oil were α-bisabolol oxide A (18.6%), d-limonene (8.82%), and α-bisabolol oxide B (7.13%). A low amount of chamazulene was observed in both essential and recovery oils, with amounts of 0.73% and 3.50%, respectively. Recovery oil, at a concentration of 75 and 100 µL/mL, showed fungal mycelial inhibition (FMI) percentage for the growth of A. niger, with values of 78% and 85%, respectively. At a concentration of 100 µL/mL, both oils showed 100% FMI of A. terreus. Oils showed weak activity against the growth of A. flavus. Essential oils at 100 µL/mL had good activity against the growth of F. culmorum, with FMI of 86.6%. The results suggest the potential use of essential and recovery oils from M. chamomilla fresh flowers as environmentally friendly bio-fungicides. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Optimization of Enzyme-Assisted Extraction of Flavonoids from Corn Husks
Processes 2019, 7(11), 804; https://doi.org/10.3390/pr7110804 - 03 Nov 2019
Cited by 2
Abstract
Corn husks are an important byproduct of the corn processing industry. Although they are a rich source of bioactive compounds, especially flavonoids, corn husks are usually disposed of or used as animal feed. In this paper, we investigate their recovery by an enzyme-assisted [...] Read more.
Corn husks are an important byproduct of the corn processing industry. Although they are a rich source of bioactive compounds, especially flavonoids, corn husks are usually disposed of or used as animal feed. In this paper, we investigate their recovery by an enzyme-assisted extraction process consisting of a pretreatment of the plant material with cellulase followed by solvent extraction with aqueous ethanol. A four-factor, three-level Box–Behnken design combined with the response surface methodology was used to optimize the enzyme dosage (0.3–0.5 g/100 g), incubation time (1.5–2.5 h), liquid-to-solid ratio (30–40 mL g−1) and ethanol concentration in the solvent (60–80% v/v). Under the optimal conditions, about 1.3 g of total flavonoids per 100 g of dry waste were recovered. A statistical analysis of the results was performed to provide a quantitative estimation of the influence of the four factors, alone or in combination, on the extraction yields. Overall, the results from this study indicate that corn husks are a valuable source of flavonoids and that they can be easily recovered by a sustainable and environmentally friendly extraction process. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Oil Recovery from Palm Kernel Meal Using Subcritical Water Extraction in a Stirred Tank Reactor
Processes 2019, 7(11), 797; https://doi.org/10.3390/pr7110797 - 02 Nov 2019
Cited by 1
Abstract
Palm kernel meal (PKM) is one of the main byproducts of the oil palm industry. PKM can be obtained as the result of solvent or mechanical extraction of palm kernel oil; in both cases, meal has a remaining oil content that could be [...] Read more.
Palm kernel meal (PKM) is one of the main byproducts of the oil palm industry. PKM can be obtained as the result of solvent or mechanical extraction of palm kernel oil; in both cases, meal has a remaining oil content that could be recovered. In this work, PKM coming from a mechanical pressing extraction system with an initial oil content between 7 to 8% (wt.) was treated with subcritical water in a batch stirred reactor. To find the proper operational conditions, a three-step experimental process was performed. Extraction temperature, reaction time, particle size and alkaline catalyst usage were selected as process factors. After subcritical extraction, the system was cooled down and depressurized; then oil phase was separated by centrifugation. After extraction, meal was oven-dried at 80 °C. A maximum recovery of 0.034 kg-oil/kg-meal was obtained at 423 K, 720 s and particles smaller than 0.001 m. The experimental procedure showed consistent extraction yields of 40% without modifying the quality of the obtained oil. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessCommunication
Antifungal Activity of Euclea divinorum Root and Study of its Ethnobotany and Phytopharmacology
Processes 2019, 7(10), 680; https://doi.org/10.3390/pr7100680 - 01 Oct 2019
Cited by 2
Abstract
The ethnobotanical survey of Euclea divinorum Hiern (Ebenaceae) was conducted on Soqotra Island, Yemen. The root bark is used to treat mouth, dental, dermal and blood diseases in the traditional medicine of the island. The study is the first report about the effect [...] Read more.
The ethnobotanical survey of Euclea divinorum Hiern (Ebenaceae) was conducted on Soqotra Island, Yemen. The root bark is used to treat mouth, dental, dermal and blood diseases in the traditional medicine of the island. The study is the first report about the effect of the plant root barks against six human pathogenic fungi. The non-polar dichloromethane extract of Euclea divinorum root bark showed stronger antifungal activities compared to polar direct and sequential methanolic extracts. These extracts showed significant broad antifungal activity against Absidia corymbifera, Aspergillus fumigatus, Candida krusei, Microsporum gypseum, Mucor sp. and Trichophyton mentagrophytes compared to the standard antibiotic drug nystatin. Thin-layer chromatography (TLC) revealed the presence of the naphthoquinones in the extracts. The results showed an extraction process to separate most antifungal naphthoquinones from the root bark by using non-polar solvent dichloromethane, while flavonoids remained in the polar methanolic extracts; therefore, the polar sequential and direct methanolic extracts recorded higher antioxidant activity than the non-polar extracts with less toxicity. The biological and chemical results identified the presence of antifungal and antioxidant constituents in the root bark and confirm its traditional use in Soqotra Island as crude powder to treat dental and dermal diseases and to clean teeth. Moreover, our results are compared with literature review on ethnobotany and phytopharmacology of E. divinorum to present a medicinal monograph about the plant. Full article
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Open AccessArticle
Recovering Cobalt and Sulfur in Low Grade Cobalt-Bearing V–Ti Magnetite Tailings Using Flotation Process
Processes 2019, 7(8), 536; https://doi.org/10.3390/pr7080536 - 14 Aug 2019
Cited by 9
Abstract
There is 0.032% cobalt and 0.56% sulfur in the cobalt-bearing V–Ti tailings in the Panxi Region, with the metal sulfide minerals mainly including FeS2, Fe1−xS, Co3S4, and (Fe,Co)S2, and the gangue minerals mainly [...] Read more.
There is 0.032% cobalt and 0.56% sulfur in the cobalt-bearing V–Ti tailings in the Panxi Region, with the metal sulfide minerals mainly including FeS2, Fe1−xS, Co3S4, and (Fe,Co)S2, and the gangue minerals mainly including aluminosilicate minerals. The flotation process was used to recover cobalt and sulfur in the cobalt-bearing V–Ti tailings. The results showed that an optimized cobalt–sulfur concentrate with a cobalt grade of 2.08%, sulfur content of 36.12%, sulfur recovery of 85.79%, and cobalt recovery and 84.77% were obtained by flotation process of one roughing, three sweeping, and three cleaning under roughing conditions, which employed pulp pH of 8, grinding fineness of <0.074 mm occupying 80%, flotation concentration of 30%, and dosages of butyl xanthate, copper sulfate, and pine oil of 100 g/t, 30 g/t, and 20 g/t, respectively. Optimized one sweeping, two sweeping, and three sweeping conditions used a pulp pH of 9, and dosages of butyl xanthate, copper sulfate, and pine oil of 50 g/t, 15 g/t, 10 g/t; 25 g/t, 7.5 g/t, 5 g/t; 20 g/t, 5 g/t, 5 g/t, respectively. Optimized one cleaning, two cleaning, and three cleaning condition dosages of sodium silicate of 200 g/t, 100 g/t, 50 g/t, respectively. Study of analysis and characterization of cobalt–sulfur concentrate by X-ray diffraction (XRD), automatic mineral analyzer (MLA), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) showed that the main minerals in cobalt–sulfur concentrate are FeS2, Co3S4 and (Fe,Co)S2, of which FeS2 and (Fe,Co)S2 accounted for 65.64% and Co3S4 for 22.64%. Gangue minerals accounted for 11.72%. The element Co in (Fe,Co)S2 is closely related to pyrite in the form of isomorphism, and the flotability difference between cobalt and pyrite is very small, which makes it difficult to separate cobalt and sulfur. Cobalt–sulfur concentrate can be used as raw material for further separation of cobalt and sulfur in smelting by pyrometallurgical or hydrometallurgical methods. Full article
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Open AccessArticle
Green Synthesis of Potent Antimicrobial Silver Nanoparticles Using Different Plant Extracts and Their Mixtures
Processes 2019, 7(8), 510; https://doi.org/10.3390/pr7080510 - 04 Aug 2019
Cited by 5
Abstract
Nano-sized metals have been introduced as a promising solution for microbial resistance to antimicrobial agents. Silver nanoparticles (AgNPs) have been proven to possess good antimicrobial activity. Green synthesis of AgNPs has been reported as safe, low cost and ecofriendly. This methodology uses extracts [...] Read more.
Nano-sized metals have been introduced as a promising solution for microbial resistance to antimicrobial agents. Silver nanoparticles (AgNPs) have been proven to possess good antimicrobial activity. Green synthesis of AgNPs has been reported as safe, low cost and ecofriendly. This methodology uses extracts originating from different plants to reduce silver ions from AgNO3 into nano-sized particles. In this study, extracts of several plants including ginger, garlic, capsicum and their mixtures were successfully used to produce AgNPs. Numerous spectroscopic, light scattering and microscopic techniques were employed to characterize the synthesized AgNPs. Agar well diffusion assay was performed to investigate the antimicrobial activity of AgNPs. The biosynthesized AgNPs have spherical shape with a size range of 20–70 nm. Garlic extract, pure or in mixture with ginger extract, generated AgNPs of the smallest size. The presence of the plant-origin capping agents surrounding AgNPs was proven by Fourier-transform infrared spectroscopy. The AgNPs, at a concentration of 50 µg/mL, demonstrated potent antimicrobial activity against Staphyloccocus aureus, Escherichia coli and Candida albicans as indicated by the zones of inhibitions. Our results revealed that AgNPs having potent antimicrobial activity could be prepared using different pure plant extracts and their mixtures. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Extraction Process of Polyphenols from Soybean (Glycine max L.) Sprouts: Optimization and Evaluation of Antioxidant Activity
Processes 2019, 7(8), 489; https://doi.org/10.3390/pr7080489 - 01 Aug 2019
Cited by 3
Abstract
This research aimed to optimize the total polyphenol content (TPC) extracted from soybean sprout powder under different experimental parameters, including ethanol concentration (60–100% v/v), extraction temperature (40–80 °C), extraction time (15–150 min), material:solvent ratio (1:4–1:10 g/mL), the number extraction cycles (1, 2 [...] Read more.
This research aimed to optimize the total polyphenol content (TPC) extracted from soybean sprout powder under different experimental parameters, including ethanol concentration (60–100% v/v), extraction temperature (40–80 °C), extraction time (15–150 min), material:solvent ratio (1:4–1:10 g/mL), the number extraction cycles (1, 2 and 3 times), the age of sprout (0–7 days), and the used part of the sprout (cotyledon, hypocotyl, or radicle). The obtained results were used in response surface methodology, in combination with a central composite design, to model the total polyphenol content (TPC) with respect to three variables, including ethanol concentration, extraction temperature, and material:solvent ratio. The experimental conditions for optimal recovery of TPC consisted of ethanol concentration of 88% (v/v), extraction temperature of 59 °C, material:solvent ratio of 1:6.5 g/mL, extraction time of 60 min, and 2 cycles of maceration. In addition, for maximal TPC, the sprout should undergo the germination of 5 days and the radicle fraction should be used. Based on the suggested optimum conditions, the obtained and verified TPC was 19.801 mg genistein (GE)/g dry weight (d.w.). The obtained dried extract also exhibited low antioxidant activity. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Ultrasound-Assisted Extraction of Pectin from Malus domestica ‘Fălticeni’ Apple Pomace
Processes 2019, 7(8), 488; https://doi.org/10.3390/pr7080488 - 01 Aug 2019
Cited by 4
Abstract
The use of an ultrasonic treatment for the extraction of pectin from Malus domestica ‘Fălticeni’ apple pomace, its effects on extraction yield and galacturonic acid content, and degree of esterification of the extracted pectin were investigated. The optimization of the extraction process showed [...] Read more.
The use of an ultrasonic treatment for the extraction of pectin from Malus domestica ‘Fălticeni’ apple pomace, its effects on extraction yield and galacturonic acid content, and degree of esterification of the extracted pectin were investigated. The optimization of the extraction process showed that the highest yield of 9.183% pectin, with a 98.127 g/100 g galacturonic acid content and 83.202% degree of esterification, was obtained at 100% amplitude, pH of 1.8, SLR of 1:10 g/mL, and 30 min. The pectin obtained in optimal extraction conditions was compared to commercial citrus and apple pectin in terms of chemical composition (determined by FT-IR), thermal behaviour (analyzed by differential scanning calorimetry), rheological properties, and morphological structure (analyzed by scanning electron microscopy). By comparison to commercial citrus and apple pectin samples, the FT-IR analysis of pectin extracted by ultrasound treatment confirmed the high degree of esterification and showed similarity to that of apple pectin (88.526%). It was found that the thermal behaviour of the pectin obtained by ultrasound-assisted extraction was influenced by the narrower distribution of molecular weights and the orderly molecular arrangement, while the rheological properties (high viscosity, G0, and G1) of this sample were influenced by the morphological structure and the galacturonic acid content. The correlation coefficient showed a strong positive relationship between viscosity and galacturonic acid content (r = 0.992**). Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Optimization of Microwave-Assisted Extraction of Total Phenolic and Total Flavonoid Contents from Fruits of Docynia indica (Wall.) Decne. Using Response Surface Methodology
Processes 2019, 7(8), 485; https://doi.org/10.3390/pr7080485 - 01 Aug 2019
Cited by 6
Abstract
Docynia indica (D. indica) shows various useful biological activities, such as antioxidant, anti-inflammatory, antibacterial effects, and positive benefits for human health. Such biological activities relate to the main phytochemicals of D. indica including phenolic and flavonoid. However, isolation for phenolic and [...] Read more.
Docynia indica (D. indica) shows various useful biological activities, such as antioxidant, anti-inflammatory, antibacterial effects, and positive benefits for human health. Such biological activities relate to the main phytochemicals of D. indica including phenolic and flavonoid. However, isolation for phenolic and flavonoid by popular methods such as hot extraction, soxhlet extraction, and ultrasonic extraction have been relatively ineffective. Therefore, in this study, microwave-assisted extraction (MAE) was used for the extraction of total phenolic and total flavonoid from D. indica. The optimization experiments were conducted based on response surface methodology (RMS) according to a central composite design with four independent variables: extraction time (min), ethanol concentration (%, v/v), microwave power (W), and pH of the solvent. Three dependent variables were total phenolic content (TPC), total flavonoid content (TFC), and yield. The optimal conditions for the extraction of phenolic and flavonoid from D. indica were: extraction time of 50 min, ethanol concentration of 65%, microwave power of 440 W, and solvent pH of 5.4. These conditions corresponded to TPC, TFC, and yield values of 33.57 ± 0.12 (mg GAE/g), 25.01 ± 0.11 (mg QE/g) and 33.44 ± 0.14 (%), respectively. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
The Effect of Extraction Methods on Preliminary Structural Properties and Antioxidant Activities of Polysaccharides from Lactarius vividus
Processes 2019, 7(8), 482; https://doi.org/10.3390/pr7080482 - 30 Jul 2019
Cited by 2
Abstract
Four polysaccharides (LVP-u, LVP-m, LVP-e, and LVP-h) were extracted from the fruiting bodies of Lactarius vividus by an ultrasonic-assisted extraction method, microwave-assisted extraction method, enzyme-assisted extraction method, and hot water extraction method, respectively. Then, the effect of extraction methods on yields, preliminary structural [...] Read more.
Four polysaccharides (LVP-u, LVP-m, LVP-e, and LVP-h) were extracted from the fruiting bodies of Lactarius vividus by an ultrasonic-assisted extraction method, microwave-assisted extraction method, enzyme-assisted extraction method, and hot water extraction method, respectively. Then, the effect of extraction methods on yields, preliminary structural properties, and antioxidant activities was systematically investigated using the weighing method, chemical composition analysis, high-performance gel permeation chromatography (HPGPC), high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), radical scavenging, and metal ion chelating assays. Results demonstrated that the four L. vividus polysaccharides (LVPs) were all combined with protein, and the yield of LVP-u was higher than others. Molecular weight distribution, monosaccharide and amino acid compositions, and microstructures among the four LVPs were significantly different. Moreover, the LVPs showed significant antioxidant activities in a dose-dependent manner, and LVP-e demonstrated better antioxidant activities in superoxide anion radical scavenging activity assays and metal ion chelating activity assays, while LVP-u showed higher activity in its hydroxyl radical scavenging ability. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Sustainable Green Procedure for Extraction of Hesperidin from Selected Croatian Mandarin Peels
Processes 2019, 7(7), 469; https://doi.org/10.3390/pr7070469 - 20 Jul 2019
Cited by 3
Abstract
The peels of Citrus reticulata Blanco mandarin cultivars of different Croatian varieties (Zorica rana, Chahara, Okitsu, Kuno) were extracted using 15 different choline chloride-based deep eutectic solvents (DESs) at 50 °C for 30 min and with 20% water [...] Read more.
The peels of Citrus reticulata Blanco mandarin cultivars of different Croatian varieties (Zorica rana, Chahara, Okitsu, Kuno) were extracted using 15 different choline chloride-based deep eutectic solvents (DESs) at 50 °C for 30 min and with 20% water addition. The extracts were analyzed by high performance liquid chromatography with diode array detection (HPLC-DAD) to determine the most suitable DES for the extraction of hesperidin in the samples. The screening results indicated that choline chloride: acetamide (1:2) provided the most efficient hesperidin extraction (112.14 mg/g of plant), while choline chloride:citric acid (1:1) solvent showed the lowest hesperidin yield (1.44 mg/g of plant). The Box–Behnken design was employed to optimize extraction parameters for each variety of mandarin peel, including extraction time, temperature and water content on hesperidin extraction. The results indicated that hesperidin content in mandarin peels was completely variety-dependent. Being a novel and efficient green media for hesperidin extraction, deep eutectic solvents could also serve as promising solvent systems for the production of extracts rich in bioactive compounds. Full article
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Open AccessArticle
Optimization of Total Anthocyanin Content, Stability and Antioxidant Evaluation of the Anthocyanin Extract from Vietnamese Carissa Carandas L. Fruits
Processes 2019, 7(7), 468; https://doi.org/10.3390/pr7070468 - 20 Jul 2019
Cited by 5
Abstract
In this study, the extraction of anthocyanin colorant from karanda fruit (Carissa carandas L.) was carried out and optimized with multiple single factor assays. Selected conditions for yield maximization consisted of ripen fruits with black-purple color, material size of thin slices (1.0–1.5 [...] Read more.
In this study, the extraction of anthocyanin colorant from karanda fruit (Carissa carandas L.) was carried out and optimized with multiple single factor assays. Selected conditions for yield maximization consisted of ripen fruits with black-purple color, material size of thin slices (1.0–1.5 mm), solvent of EtOH 50%, material/ solvent ratio of 1:3, temperature of 50 °C, extraction time of 45 min, and two extraction cycles. The anthocyanin content in the extract was 277.2 mg/L, which is equivalent to 9.33 mg anthocyanin per gram of dry material. Aqueous solutions of the extract and dried extracts from Carissa carandas fruit were evaluated for stability at two temperature conditions, namely room temperature (30 ± 2 °C) and 45 °C. The temperature exerted great impact on color change, anthocyanin content and the degree of polymerization of anthocyanin. Aqueous solutions of extract with citric acid (3.0–5.0 g/L) were generally more color stable and less anthocyanin degradable than those without citric acid. In the DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging assay, The half maximal inhibitory concentration (IC50) of the dried extract was 87.56 μg/mL, which was approximately 29 times higher than that of vitamin C. After 3-month storage at −18 °C, IC50 of the dried extract was 173.67 μg/mL. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Separation of Protein-Binding Anthraquinones from Semen Cassiae Using Two-Stage Foam Fractionation
Processes 2019, 7(7), 463; https://doi.org/10.3390/pr7070463 - 19 Jul 2019
Cited by 1
Abstract
Anthraquinones are compounds of high medicinal value in many plants. Based on their good protein binding affinity, foam fractionation was attempted to separate them using proteins in the aqueous extract of Semen Cassiae as collectors. Firstly, the interaction between anthraquinones and Semen Cassiae [...] Read more.
Anthraquinones are compounds of high medicinal value in many plants. Based on their good protein binding affinity, foam fractionation was attempted to separate them using proteins in the aqueous extract of Semen Cassiae as collectors. Firstly, the interaction between anthraquinones and Semen Cassiae proteins has been analyzed by the Stem–Volmer equation with physcion as a standard. The results show that physcion had good interaction with the proteins via hydrophobic forces. More importantly, the proteins effectively assisted the foam fractionation of several anthraquinones including aurantio-obtusifolin, aloe-emodin, rhein, emodin, chrysophanol, and physcion. On this basis, a two-stage foam fractionation technology was developed for process intensification using a foam fractionation with vertical sieve trays (VSTs). VSTs, initial feed concentration of total anthraquinones, temperature, volumetric air flow rate and pore diameter of gas distributor had significant effects on enrichment ratio and recovery yield of anthraquinones. Under suitable conditions, the enrichment ratio of total anthraquinones reached 47.0 ± 4.5 with a concentration of 939 ± 94 mg/L in the foamate while their total recovery percentage reached more than 47.7%. In addition, foam fractionation also increased the purity and hydroxyl radical scavenging activity of total anthraquinones. The results had significant implications for the separation of anthraquinones from Semen Cassiae. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Extraction Process, Identification of Fatty Acids, Tocopherols, Sterols and Phenolic Constituents, and Antioxidant Evaluation of Seed Oils from Five Fabaceae Species
Processes 2019, 7(7), 456; https://doi.org/10.3390/pr7070456 - 16 Jul 2019
Cited by 3
Abstract
The present study aimed to extract seed oils and characterize the chemical composition, including fatty acid profiles, tocopherols, sterols, and total phenolics of oils and extracts from five Fabaceae seeds: Glycine soja, Vigna angularis, Phaseolus lunatus, Phaseolus vulgarisand, and [...] Read more.
The present study aimed to extract seed oils and characterize the chemical composition, including fatty acid profiles, tocopherols, sterols, and total phenolics of oils and extracts from five Fabaceae seeds: Glycine soja, Vigna angularis, Phaseolus lunatus, Phaseolus vulgarisand, and Phaseolus coccineus. The composition and content of all substance layers in total lipids of the extracted seed oils from five Fabaceae species contain: polar lipid (PL), sterol (ST), diacylglycerol (DG), triacylglycerol (TG), free fatty acid (FFA), and hydrocarbon and wax (HC + W). Antioxidant activity determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method was also estimated. Among these examined samples, Phaseolus vulgarisand and Phaseolus coccineus seed oils showed high content of α-linolenic acid (59.39% and 49.38%, respectively). Linoleic acid was abundantly found in Vigna angularis (49.01%). Ferunic and caffeic acid, γ-tocopherol, and β-sistosterol were the main ingredients present in the species studied. The V. angularis seed extract displayed significant antioxidant activity. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Isolation Process and Compound Identification of Agarwood Essential Oils from Aquilaria crassna Cultivated at Three Different Locations in Vietnam
Processes 2019, 7(7), 432; https://doi.org/10.3390/pr7070432 - 09 Jul 2019
Cited by 3
Abstract
Agarwood and agarwood essential oils are commodities with great commercial value. In Vietnam, the agarwood industry has been growing, with more than 10,000 ha of forest land reserved for the cultivation of Aquilaria crassna, an agarwood-producing tree. The aim of this study [...] Read more.
Agarwood and agarwood essential oils are commodities with great commercial value. In Vietnam, the agarwood industry has been growing, with more than 10,000 ha of forest land reserved for the cultivation of Aquilaria crassna, an agarwood-producing tree. The aim of this study was to present a hydrodistillation process to recover agarwood essential oil and to compare chemical compositions of agarwood samples harvested from various locations in Vietnam. Three agarwood samples representing products from A. crassna trees cultivated in the provinces of Bac Giang and Khanh Hoa, and on the Phu Quoc island (Kien Giang province) of Vietnam were subjected to hydrodistillation, resulting in essential oil yields of 0.32%, 0.27%, and 0.25% (w/w), respectively. Using GC–MS analysis, a total of 44 volatile compounds were identified in the obtained oils. Most of the constituents were oxygenated sesquiterpenes and had been previously found in other agarwood oil samples. Notable compounds of other chemical classes were aromatics and fatty acids. The three oil samples showed a common volatile profile, which is characterized by the dominance of eremophilane, agarofurans, and eudesmane sesquiterpenes, while vetispirane and guaiane sesquiterpenes were found in smaller quantities. Desired compounds, such as neopetasane (7.47–8.29%), dihydrokaranone (2.63–3.59%), β-agarofuran (3.04–6.18%), and agarospirol (2.98–3.42%), were present in substantial quantities, suggesting that the essential oils could be commercialized as fragrant materials of high value. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Increasing Iron and Reducing Phosphorus Grades of Magnetic-Roasted High-Phosphorus Oolitic Iron Ore by Low-Intensity Magnetic Separation–Reverse Flotation
Processes 2019, 7(6), 388; https://doi.org/10.3390/pr7060388 - 21 Jun 2019
Cited by 10
Abstract
High-phosphorus oolitic iron ore, treated by suspended flash magnetic roasting, contained 42.73% iron (mainly present as magnetite) and 0.93% phosphorus (present as collophane). Low-intensity magnetic separation (LIMS) was combined with reverse flotation to increase the iron and reduce the phosphorus contents of the [...] Read more.
High-phosphorus oolitic iron ore, treated by suspended flash magnetic roasting, contained 42.73% iron (mainly present as magnetite) and 0.93% phosphorus (present as collophane). Low-intensity magnetic separation (LIMS) was combined with reverse flotation to increase the iron and reduce the phosphorus contents of the roasted product. The results showed that an optimized iron ore concentrate with an iron grade of 67.54%, phosphorus content of 0.11%, and iron recovery of 78.99% were obtained under LIMS conditions that employed a grind of 95% −0.038 mm and a magnetic field of 0.10 T. Optimized rougher reverse-flotation conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 800 g/t, 1000 g/t, and 40 g/t, respectively; optimized scavenging conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 400 g/t, 500 g/t, and 20 g/t, respectively. Study of the mechanism of phosphorus reduction showed that the toluenesulfonamide could be adsorbed on the surface of quartz after the action of starch, but adsorption was significantly weakened. The starch inhibitor negatively affected adsorption on quartz, but positively influenced adsorption of phosphorus minerals. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Supercritical Fluid Extraction of Fat and Caffeine with Theobromine Retention in the Cocoa Shell
Processes 2019, 7(6), 385; https://doi.org/10.3390/pr7060385 - 21 Jun 2019
Cited by 2
Abstract
The cocoa shell is a residue of low commercial value, which represents an alternative for obtaining substances of added value for the food and pharmaceutical industry. Substances of interest in the shell include fat and methylxanthines (theobromine and caffeine). In order to obtain [...] Read more.
The cocoa shell is a residue of low commercial value, which represents an alternative for obtaining substances of added value for the food and pharmaceutical industry. Substances of interest in the shell include fat and methylxanthines (theobromine and caffeine). In order to obtain the extraction behavior with supercritical CO2, a 23 factorial design was proposed with six central points, taking dynamic extraction into consideration. The following factors were involved: pressure (2,000–6,000 psi), temperature (313–333 K), and time (30–90 min). The obtained yield was between 3.66% and 15.30%. Fat was the substance that was extracted most effectively (94.73%). Caffeine demonstrated variability in the residue, with at least six treatments that exceeded a removal rate of more than 90%, while it was practically impossible to extract theobromine. The difference with regard to the extraction of theobromine may be attributed to its low solubility. Characterization using FT–IR showed the modifications before and after the process, providing clear evidence of the changes corresponding to the fat at 2,924, 2,854 and 1,745 cm−1. The results presented establish the basis for the extraction of substances such as fats and methylxanthines from a cocoa shell with the use of CO2. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Separation Emulsion via Non-Ionic Surfactant: An Optimization
Processes 2019, 7(6), 382; https://doi.org/10.3390/pr7060382 - 20 Jun 2019
Cited by 4
Abstract
Achieving emulsion stability in the petroleum industry is a major challenge due to several problems encountered in the oil refining process, such as corrosion in equipment, high-pressure drops in pipelines, and catalyst poisoning in upstream facilities. Thus, several methods are applied for emulsion [...] Read more.
Achieving emulsion stability in the petroleum industry is a major challenge due to several problems encountered in the oil refining process, such as corrosion in equipment, high-pressure drops in pipelines, and catalyst poisoning in upstream facilities. Thus, several methods are applied for emulsion treatment and chemical treatment using surface-active agents, a fundamental method in the petroleum industry. The present work investigated the performance of a non-ionic surfactant in separating water in a crude oil emulsion via the bottle test technique. Then, a Fractional Factorial Design (2K−1) was used to characterise the effect of significant variables. In particular, a Pareto chart was employed and factors such as demulsifier dosage, toluene concentration, pressure, sitting time, and temperature were investigated. Accordingly, the parameters applied were further analysed using a Central Composite Design (CCD) based on the Response Surface Method (RSM). The experimental results based on analysis of Variance (ANOVA) show that demulsifier dosage, temperature, and sedimentation times were the main variables affecting the dehydration process, with the highest F-values being 564.74, 94.53 and 78.65 respectively. The increase in the surfactant dosage before critical concentration, temperature and sitting time leads to boosting dehydration efficiency. In addition, a mathematical model was established for the variables, with a coefficient of determination value of 0.9688. Finally, numerical optimisation was performed on the variables and the results show that the optimal values are 1000 ppm, 15.5 mL, −400 mmHg, 120 min, and 90 °C, for demulsifier dosage, toluene concentration, pressure, sitting time, and temperature, respectively. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
A Novel Technology for Separating Copper, Lead and Zinc in Flotation Concentrate by Oxidizing Roasting and Leaching
Processes 2019, 7(6), 376; https://doi.org/10.3390/pr7060376 - 18 Jun 2019
Cited by 2
Abstract
In this work, oxidizing roasting was combined with leaching to separate copper, lead, and zinc from a concentrate obtained by bulk flotation of a low-grade ore sourced from the Jiama mining area of Tibet. The flotation concentrate contained 7.79% Cu, 22.00% Pb, 4.81% [...] Read more.
In this work, oxidizing roasting was combined with leaching to separate copper, lead, and zinc from a concentrate obtained by bulk flotation of a low-grade ore sourced from the Jiama mining area of Tibet. The flotation concentrate contained 7.79% Cu, 22.00% Pb, 4.81% Zn, 8.24% S, and 12.15% CaO; copper sulfide accounted for 76.97% of the copper, lead sulfide for 25.55% of the lead, and zinc sulfide for 67.66% of the zinc. After oxidizing roasting of the flotation concentrate, the S content in the roasting slag decreased to 0.22%, indicating that most sulfide in the concentrate was transformed to oxide, which was beneficial to leaching. The calcine was subjected to sulfuric acid leaching for separation of copper, lead, and zinc; i.e., copper and zinc were leached, and lead was retained in the residue. The optimum parameters of the leaching process were: a leaching temperature of 55 °C; sulfuric acid added at 828 kg/t calcine; a liquid:solid ratio of 3:1; and a leaching time of 1.5 h. Under these conditions, the extents of leaching of copper and zinc were 87.43% and 64.38%, respectively. Copper and zinc in the leaching solution could be further separated by electrowinning. The effects of leaching parameters on the extents of leaching of copper and zinc were further revealed by X-ray diffraction and scanning electron microscopy analysis. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Lipid Isolation Process and Study on Some Molecular Species of Polar Lipid Isolated from Seed of Madhuca ellitica
Processes 2019, 7(6), 375; https://doi.org/10.3390/pr7060375 - 17 Jun 2019
Cited by 1
Abstract
This study attempted the lipid extraction process from the seeds of Madhuca ellitica, a lipid-rich plant, and conducted a lipidomic analysis on molecular species of the obtained product. Total lipids of the crude seeds were found to contain 11.2% of polar lipids. [...] Read more.
This study attempted the lipid extraction process from the seeds of Madhuca ellitica, a lipid-rich plant, and conducted a lipidomic analysis on molecular species of the obtained product. Total lipids of the crude seeds were found to contain 11.2% of polar lipids. The major fatty acids (FAs) of the polar lipids were palmitic (16:0), stearic (18:0), oleic (18:1n-9), and linoleic (18:2n-6) acids, which amounted to 28.5, 12.5, 44.8, and 13.2% of total FAs, respectively. The content and chemical structures of individual molecular species of phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidic acid (PA), and sulfoquinovosyldiacylglycerol (SQDG) were determined by HPLC with a tandem high-resolution mass spectrometry (HRMS). The major molecular species were 18:1/18:2 PE, 16:0/18:1 PC, 18:1/18:2 PC, 16:0/18:2 PG, 16:0/18:1 PG, 16:1/18:1 PI, 16:0/18:1 PI, 18:0/18:2 PI, 16:0/18:1 PA, 18:1/18:2 PA, 16:0/18:1 SQDG, and 18:0/18:1 SQDG. The application of a tandem HRMS allows us to determine the content of each isomer in pairs of the monoisotopic molecular species, for example, 18:0/18:2 and 18:1/18:1. The evaluation of the seed polar lipid profile will be helpful for developing the potential of this tree for nutritive and industrial uses. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Yield, Phytochemical Constituents, and Antibacterial Activity of Essential Oils from the Leaves/Twigs, Branches, Branch Wood, and Branch Bark of Sour Orange (Citrus aurantium L.)
Processes 2019, 7(6), 363; https://doi.org/10.3390/pr7060363 - 11 Jun 2019
Cited by 19
Abstract
In the present work, essential oils (EOs) extracted from different parts of sour orange Citrus aurantium (green leaves/twigs, small branches, wooden branches, and branch bark) were studied through gas chromatography coupled with mass spectrometry (GC/MS). Furthermore, the EOs in the amounts of 5, [...] Read more.
In the present work, essential oils (EOs) extracted from different parts of sour orange Citrus aurantium (green leaves/twigs, small branches, wooden branches, and branch bark) were studied through gas chromatography coupled with mass spectrometry (GC/MS). Furthermore, the EOs in the amounts of 5, 10, 15, 20, and 25 µL were studied for their antibacterial activity against three pathogenic bacteria, Agrobacterium tumefaciens, Dickeya solani, and Erwinia amylovora. The main EO compounds in the leaves/twigs were 4-terpineol (22.59%), D-limonene (16.67%), 4-carvomenthenol (12.84%), and linalool (7.82%). In small green branches, they were D-limonene (71.57%), dodecane (4.80%), oleic acid (2.72%), and trans-palmitoleic acid (2.62%), while in branch bark were D-limonene (54.61%), γ-terpinene (6.68%), dodecane (5.73%), and dimethyl anthranilate (3.13%), and in branch wood were D-limonene (38.13%), dimethyl anthranilate (8.13%), (-)-β-fenchol (6.83%), and dodecane (5.31%). At 25 µL, the EO from branches showed the highest activity against A. tumefaciens (IZ value of 17.66 mm), and leaves/twigs EO against D. solani and E. amylovora had an IZ value of 17.33 mm. It could be concluded for the first time that the wood and branch bark of C. aurantium are a source of phytochemicals, with D-limonene being the predominant compound in the EO, with potential antibacterial activities. The compounds identified in all the studied parts might be appropriate for many applications, such as antimicrobial agents, cosmetics, and pharmaceuticals. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Purification of Amygdalin from the Concentrated Debitterizing-Water of Apricot Kernelsusing XDA-1 Resin
Processes 2019, 7(6), 359; https://doi.org/10.3390/pr7060359 - 10 Jun 2019
Cited by 2
Abstract
In this study, six macroporous resins were screened on their adsorption and de-adsorption characteristics for the amygdalin in the debitterizing wastewater concentrate (DWC). The results indicate that the XDA-1 resin exerts good adsorption and de-adsorption capacities on the amygdalin. In order to further [...] Read more.
In this study, six macroporous resins were screened on their adsorption and de-adsorption characteristics for the amygdalin in the debitterizing wastewater concentrate (DWC). The results indicate that the XDA-1 resin exerts good adsorption and de-adsorption capacities on the amygdalin. In order to further confirm its feasibility, the factors affecting the capacity of adsorption and de-adsorption, and its adsorption mechanisms were also investigated. The results suggest that the optimum purification conditions were as follows: loading concentration of samples with 78.05 mg/mL, flow rate of 2 mL/min, and de-adsorption with 80% ethanol solution. The recovery rate was 88.75% and the relative content achieved 61.58% after purification by XDA-1 resin. The Freundlich model can be used to describe the entirety of the exothermic and physical adsorption processes. In summary, the conclusion which can be made from this research is that the wastewater generated from the debitterizing of apricot kernels can be well treated by resin to recycle the amygdalin and reduce its pollution to environment. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Simple Preparation of Diverse Neoagaro-Oligosaccharides
Processes 2019, 7(5), 267; https://doi.org/10.3390/pr7050267 - 07 May 2019
Cited by 3
Abstract
A simple method for obtaining pure and well-defined oligosaccharides was established by hydrolyzing agar with β-agarase from Vibrio natriegens. The conditions for enzymolysis were optimized as follows: a temperature of 45 °C, a pH of 8.5, a substrate concentration of 0.3%, an [...] Read more.
A simple method for obtaining pure and well-defined oligosaccharides was established by hydrolyzing agar with β-agarase from Vibrio natriegens. The conditions for enzymolysis were optimized as follows: a temperature of 45 °C, a pH of 8.5, a substrate concentration of 0.3%, an enzyme amount of 100 U/g and an enzymolysis time of 20 h. Neoagaro-oligosaccharides with different degrees of polymerization were obtained by hydrolyzing agar with β-agarase for different lengths of time. After removing pigments using activated carbon and salts by dialyzing, the enzyme hydrolysis solution was separated with Bio-Gel P2 column chromatography. Neoagaro-oligosaccharides with different degrees of polymerization were acquired. By comparing with authentic standard substances, along with further confirmation by FTIR, MS and NMR, structures of the purified neoagaro-oligosaccharides were identified as neoagarobiose (NA2), neoagaroteraose (NA4), neoagarohexaose (NA6), neoagarooctaose (NA8), neoagaro-decaose (NA10) and neoagarododecaose (NA12) with purities of more than 97.0%. The present study established a method for the preparation of various neoagaro-oligosaccharides that may be of great significance for further study of their bioactivities. Full article
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Open AccessArticle
A Process for the Separation of Noble Metals from HCl Liquor Containing Gold(III), Palladium(II), Platinum(IV), Rhodium(III), and Iridium(IV) by Solvent Extraction
Processes 2019, 7(5), 243; https://doi.org/10.3390/pr7050243 - 26 Apr 2019
Cited by 5
Abstract
The demand for noble metals is increasing, owing to their excellent chemical and physical properties. In order to meet the demand, the recovery of noble metals with high purity from diverse secondary resources, which contain small amounts of noble metals, is of immense [...] Read more.
The demand for noble metals is increasing, owing to their excellent chemical and physical properties. In order to meet the demand, the recovery of noble metals with high purity from diverse secondary resources, which contain small amounts of noble metals, is of immense value. In this work, the possibility of the separation of Au(III), Pd(II), Pt(IV), Rh(III), and Ir(IV) by solvent extraction from a synthetic HCl solution is investigated. Only Au(III) was selectively extracted by Cyanex 272 in the HCl concentration range from 0.5 M to 9 M, leaving the other metal ions in the raffinate. The loaded Au(III) in Cyanex 272 was efficiently stripped by (NH2)2CS. The other four noble metals were sequentially separated on the basis of the procedures reported in the previous work. The mass balance showed that about 98% of each metal, except Pt(IV), was recovered by the proposed process. An efficient process for the recovery of the five noble metal ions from the HCl leaching solution of secondary resources containing these metals can be developed. Full article
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Open AccessArticle
Antifungal and Antibacterial Activities of Musa paradisiaca L. Peel Extract: HPLC Analysis of Phenolic and Flavonoid Contents
Processes 2019, 7(4), 215; https://doi.org/10.3390/pr7040215 - 15 Apr 2019
Cited by 13
Abstract
In the present study, Melia azedarach wood samples that were treated with the methanolic extract of Musa paradisiaca L. peels were evaluated for their antibacterial and antifungal activities against Agrobacterium tumefaciens, Dickeya solani, Erwinia amylovora, Pseudomonas cichorii, Serratia pylmuthica, [...] Read more.
In the present study, Melia azedarach wood samples that were treated with the methanolic extract of Musa paradisiaca L. peels were evaluated for their antibacterial and antifungal activities against Agrobacterium tumefaciens, Dickeya solani, Erwinia amylovora, Pseudomonas cichorii, Serratia pylmuthica, Fusarium culmorum, and Rhizoctonia solani. The strongest antibacterial activity was only found against A. tumefaciens (inhibition zone 90 mm), while the other bacterial strains showed resistance to wood that was treated with the extract. Potential antifungal activity against F. culmorum and R. solani was observed; the mycelial growth inhibition percentages reached 68.88% and 94.07%, respectively, in wood samples that were treated with the 3% methanolic extract of M. paradisiaca peel. HPLC analysis demonstrated the presence of seven phenolic compounds and three flavonoid compounds, as their peaks were matched with the standard compounds in a HPLC analysis. The major constituents of phenolic and flavonoid compounds in mg/100 g dry extract (DE) were ellagic acid (16.19), gallic acid (7.73), rutin (973.08), myricetin (11.52), and naringenin (8.47). The results demonstrated the potential effects of banana peel extract as a natural compound that can protect wood from molds while in use. Full article
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Open AccessArticle
Green Synthesis of Silver Nanoparticles Using Bilberry and Red Currant Waste Extracts
Processes 2019, 7(4), 193; https://doi.org/10.3390/pr7040193 - 03 Apr 2019
Cited by 5
Abstract
The production of silver nanoparticles (Ag-NPs) from bilberry waste (BW) and red currant waste (RCW) extracts was studied. Red fruit extracts were obtained by treating BW and RCW with aqueous ethanol (50% v/v) at 40 °C. The formation of nanoparticles [...] Read more.
The production of silver nanoparticles (Ag-NPs) from bilberry waste (BW) and red currant waste (RCW) extracts was studied. Red fruit extracts were obtained by treating BW and RCW with aqueous ethanol (50% v/v) at 40 °C. The formation of nanoparticles was monitored spectrophotometrically by measuring the intensity of the surface plasmon resonance band (SPR) of silver. The effects of temperature (20–60 °C) and pH (8–12) on the reaction kinetics and on the properties of Ag-NPs were investigated. Characterization by XRD and dynamic light scattering (DLS) techniques showed that Ag-NPs were highly crystalline, with a face-centered cubic structure and a hydrodynamic diameter of 25–65 nm. The zeta potential was in the range of −35.6 to −20.5 mV. Nanoparticles obtained from BW were slightly smaller and more stable than those from RCW. A kinetic analysis by the initial-rate method showed that there was an optimum pH, around 11, for the production of Ag-NPs. Overall, the results obtained suggest that BW and RCW can be advantageously used as a source of reducing and stabilizing agents for the green synthesis of Ag-NPs. Full article
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Open AccessArticle
Optimal Ultrasound-Assisted Process Extraction, Characterization, and Functional Product Development from Flaxseed Meal Derived Polysaccharide Gum
Processes 2019, 7(4), 189; https://doi.org/10.3390/pr7040189 - 02 Apr 2019
Cited by 2
Abstract
Flaxseed (Linum usitatissimum L.) has several health-promoting applications as dietary food ingredient supplementation, owing to presence of high quality of oil, polyunsaturated fatty acids, high dietary fiber and protein contents. The presence of different anti-nutritional components, for example cyanogens (HCN) and tannins [...] Read more.
Flaxseed (Linum usitatissimum L.) has several health-promoting applications as dietary food ingredient supplementation, owing to presence of high quality of oil, polyunsaturated fatty acids, high dietary fiber and protein contents. The presence of different anti-nutritional components, for example cyanogens (HCN) and tannins in meal, limits its application for food purposes. The study was conducted to observe the effect of ultrasound-assisted extraction on polysaccharide gums (PSG) yield using response surface methodology. The selected variables were sonication temperature (°C), water to meal ratio, sonication amplitude level (%), sonication pH, and sonication time (min). Ultrasound-assisted extraction significantly reduced the anti-nutritional components like HCN and tannins. The extracted PSG yield from partially defatted flaxseed meal (PDFM) samples varied to a minimum of 7.24% to a maximum of 11.04% when extraction temperature (°C) and amplitude level (%) varied from −1 to +1 and keeping all other variables constant at mean value. Physiochemical and functional properties of extracted PSG were studied. Yoghurt with different treatment combinations were prepared by supplementing flaxseed-derived PSG as stabilizer ranging from 0.25% to 1.5%, keeping baseline samples without PSG as control. Functional properties of PSG-supplemented yoghurt such as pH, syneresis, and viscosity were determined to assess the influence of PSG supplementation on yoghurt quality. In the organoleptic behavior of PSG-supplemented yoghurt, no adverse effect on the flavor have been observed, but the textural properties vary significantly among different treatments. Overall, the acceptability of 1% PSG-supplemented yoghurt was significantly higher than other treatments. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Comparative Evaluation of Selected Biological Methods for the Removal of Hydrophilic and Hydrophobic Odorous VOCs from Air
Processes 2019, 7(4), 187; https://doi.org/10.3390/pr7040187 - 01 Apr 2019
Cited by 11
Abstract
Due to increasingly stringent legal regulations as well as increasing social awareness, the removal of odorous volatile organic compounds (VOCs) from air is gaining importance. This paper presents the strategy to compare selected biological methods intended for the removal of different air pollutants, [...] Read more.
Due to increasingly stringent legal regulations as well as increasing social awareness, the removal of odorous volatile organic compounds (VOCs) from air is gaining importance. This paper presents the strategy to compare selected biological methods intended for the removal of different air pollutants, especially of odorous character. Biofiltration, biotrickling filtration and bioscrubbing technologies are evaluated in terms of their suitability for the effective removal of either hydrophilic or hydrophobic VOCs as well as typical inorganic odorous compounds. A pairwise comparison model was used to assess the performance of selected biological processes of air treatment. Process efficiency, economic, technical and environmental aspects of the treatment methods are taken into consideration. The results of the calculations reveal that biotrickling filtration is the most efficient method for the removal of hydrophilic VOCs while biofilters enable the most efficient removal of hydrophobic VOCs. Additionally, a simple approach for preliminary method selection based on a decision tree is proposed. The presented evaluation strategies may be especially helpful when considering the treatment strategy for air polluted with various types of odorous compounds. Full article
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Open AccessArticle
Novel Deep Eutectic Solvent Based on Levulinic Acid and 1,4-Butanediol as an Extraction Media for Bioactive Alkaloid Rutaecarpine
Processes 2019, 7(3), 171; https://doi.org/10.3390/pr7030171 - 24 Mar 2019
Cited by 5
Abstract
Deep eutectic solvents (DESs) are increasingly receiving interest as a new type of green and sustainable alternative to hazardous organic solvents. In this work, a novel DES based on levulinic acid (La) and 1,4-butanediol (Buta) as an extraction media was developed for extracting [...] Read more.
Deep eutectic solvents (DESs) are increasingly receiving interest as a new type of green and sustainable alternative to hazardous organic solvents. In this work, a novel DES based on levulinic acid (La) and 1,4-butanediol (Buta) as an extraction media was developed for extracting the bioactive alkaloid rutaecarpine from the unripe fruits of Tetradium ruticarpum. 24 different DESs consisting of choline chloride, betaine, sugar alcohols, organic acids, amides, and sugars were prepared and tailored to test their extraction efficiency. After initial screening, a hydrophilic DES composed of La and Buta with 1:0.5 molar ratio containing 25% water was tailored for the highest extraction efficiency, followed by the optimizations of molar ratio and water content. The interaction between the molecules of La-Buta DES was investigated by nuclear magnetic resonance spectroscopy in order to confirm its deep eutectic supermolecular structure feature. The extraction conditions were optimized by single-factor experiments, including extraction temperature, extraction time, and solid-liquid ratio. The developed La-Buta DES extraction procedure was successfully applied for the analysis of rutaecarpine in Chinese patent medicines containing the unripe fruits of T. ruticarpum. The excellent property of La-Buta DES indicated its potential as a promising green solvent instead of conventional organic solvent for the extraction of rutaecarpine from the unripe fruits of T. ruticarpum, and that it can used as a sustainable and safe extraction media for other applications. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Water–Organic Solvent Extraction of Phenolic Antioxidants from Brewers’ Spent Grain
Processes 2019, 7(3), 126; https://doi.org/10.3390/pr7030126 - 01 Mar 2019
Cited by 11
Abstract
Brewers’ spent grain (BSG) is the most abundant by-product of the brewing process. BSG is currently disposed of or used as a supplement for animal feed, although it contains significant amounts of bioactive compounds of great interest to the pharmaceutical, cosmetic and food [...] Read more.
Brewers’ spent grain (BSG) is the most abundant by-product of the brewing process. BSG is currently disposed of or used as a supplement for animal feed, although it contains significant amounts of bioactive compounds of great interest to the pharmaceutical, cosmetic and food sectors. In this study we investigate the feasibility of using a simple solvent extraction procedure to recover phenolic antioxidants from BSG. Acetone–water and ethanol–water mixtures were used as extraction solvents. Phenolic extracts obtained by treatment of BSG with the two solvent systems were characterized in terms of total phenolics and antioxidant activity. For both systems, the extraction yield was maximum at 60% (v/v) organic solvent concentration. At all solvent compositions, mixtures containing acetone provided higher extraction yields. As suggested by the strong correlation between the antioxidant activity of BSG extracts and their phenolic content, the antioxidant capacity of the extracts can be mainly attributed to polyphenols. Overall, the obtained results strongly support the exploitation of BSG as a source of phenolic antioxidants and the possibility of recovering them by a mild and green extraction process. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Effects of Caustic Extraction on Properties of Viscose Grade Dissolving Pulp
Processes 2019, 7(3), 122; https://doi.org/10.3390/pr7030122 - 27 Feb 2019
Cited by 1
Abstract
Viscose, a cellulose-based commodity fibre, is produced by pulping and bleaching of wood, yielding a high quality “dissolving pulp” which is then spun. During pulping and bleaching, effective hemicellulose extraction is required to allow fibre production. We present a design of experiments (DoE) [...] Read more.
Viscose, a cellulose-based commodity fibre, is produced by pulping and bleaching of wood, yielding a high quality “dissolving pulp” which is then spun. During pulping and bleaching, effective hemicellulose extraction is required to allow fibre production. We present a design of experiments (DoE) approach to optimise caustic extraction in a total chlorine free (TCF) bleaching sequence (O-CE-Z-P) of beech wood sulphite pulp. Temperature and sodium hydroxide concentration were varied to identify highest xylan extraction yield, and a maximum xylan removal of 83% was achieved at 20 °C and 120 g/L NaOH. Additionally, caustic extraction conditions were derived from the DoE model that led to pulps with high yield, high alpha cellulose content or uniform cellulose molecular weight distribution. Pulps from verification experiments exhibited good reactivity in viscose application tests. Hence, the presented O-CE-Z-P bleaching sequence can be considered as suitable for integrated viscose fibre production. We assume that the presented caustic extraction model will be useful for pulp and biorefinery researchers who work on caustic biorefinery processes involving hardwood feedstocks. Full article
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Open AccessArticle
Purification of Flavonoids from Mulberry Leaves via High-Speed Counter-Current Chromatography
Processes 2019, 7(2), 91; https://doi.org/10.3390/pr7020091 - 13 Feb 2019
Cited by 3
Abstract
In order to obtain high-purity flavonoid products, the extracts from mulberry leaves were separated and purified via high-speed counter-current chromatography (HSCCC). Moreover, the product was detected via high-performance liquid chromatography (HPLC). The characteristic absorption wavelength of the rutin standard for HSCCC detection and [...] Read more.
In order to obtain high-purity flavonoid products, the extracts from mulberry leaves were separated and purified via high-speed counter-current chromatography (HSCCC). Moreover, the product was detected via high-performance liquid chromatography (HPLC). The characteristic absorption wavelength of the rutin standard for HSCCC detection and HPLC analysis at 257 nm was tested by ultraviolet scanning analysis. The effect of solvent systems and mobile phase flow rate on the separation efficiency were then researched. Finally, the solvent system of V(ethyl acetate):V(n-butanol):V(water) = 4:1:5 was selected as the operating system for HSCCC. This work theoretically analyzed the impact of the molecular structure and polarity of flavonoids on the choice of solvent systems. The results showed that the mobile phase flow rate had a great influence on the separation efficiency. Furthermore, the separation efficiency increased as the mobile phase flow rate decreased. When the mobile phase flow rate was 5 mL/min, the peak time for flavonoids was 140 min, the retention of the stationary phase was 56.4%, and the purity of the product reached 93.8%. The results of this study greatly improved the purity of flavonoids in mulberry leaf and provided a strong support for the separation and purification of mulberry leaf extract. Full article
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Open AccessArticle
Evaluation of Conditions Affecting Properties of Gac (Momordica Cocochinensis Spreng) Oil-Loaded Solid Lipid Nanoparticles (SLNs) Synthesized Using High-Speed Homogenization Process
Processes 2019, 7(2), 90; https://doi.org/10.3390/pr7020090 - 12 Feb 2019
Cited by 14
Abstract
In this study, we attempted the preparation of gac oil-loaded solid lipid nanoparticles (SLNs) by the high-speed homogenization method using Naterol SE solid lipid, a cosmetic self-emulsifying base, and surfactant and investigated the effects of different conditions on the characteristics of the resulting [...] Read more.
In this study, we attempted the preparation of gac oil-loaded solid lipid nanoparticles (SLNs) by the high-speed homogenization method using Naterol SE solid lipid, a cosmetic self-emulsifying base, and surfactant and investigated the effects of different conditions on the characteristics of the resulting nanoparticles. The suspensions containing 5% active agents (gac-oil, w/w) were dispersed in a surfactant concentration of 5% (w/w) (Span 80:Tween 80 ratio of 28:72 w/w) and 2.5% (w/w) of solid lipid (Naterol SE) concentration. Suitable conditions for hot homogenization were 13,000 rpm, 60 min and 60 °C for speed, time and temperature, respectively. The suitable conditions for the subsequent cold homogenization were 25 min of homogenization time and 5 °C of temperature. The results showed that the mean size of SLNs-gac oil was 107 nm (measured by laser diffraction spectrometry, LDS), and dried size of SLNs-gac oil ranged from 50 to 80 nm (measured by transmission electron microscope, TEM). In addition, the study investigated the impact of gac oil content on the particle size of SLNs-gac oil and its stability under different storage conditions of UV radiation and storage temperature. At high storage temperatures, the color changes (ΔE) of the samples were more profound in comparison to that at the low storage temperature. The ΔE value of the blank sample (SLN-FREE gac-oil) was higher than that of the Gac oil-loaded SLNs samples (SLN-gac oil). Full article
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Open AccessFeature PaperArticle
Phytochemical Content of Melissa officinalis L. Herbal Preparations Appropriate for Consumption
Processes 2019, 7(2), 88; https://doi.org/10.3390/pr7020088 - 12 Feb 2019
Cited by 3
Abstract
Melissa Officinalis L. (MOL) domestic preparations appropriate for consumption were studied by monitoring content in Na, K, Ca, Li, phenolic bioactives (total phenols, hydroxycinnamic acid derivatives and flavonols), and antioxidant activity (1,1-diphenyl-2-picrylhydrazyl radical inhibition (DPPH) and ferric reducing ability (FRAP)). The effects of [...] Read more.
Melissa Officinalis L. (MOL) domestic preparations appropriate for consumption were studied by monitoring content in Na, K, Ca, Li, phenolic bioactives (total phenols, hydroxycinnamic acid derivatives and flavonols), and antioxidant activity (1,1-diphenyl-2-picrylhydrazyl radical inhibition (DPPH) and ferric reducing ability (FRAP)). The effects of practice applied, material to solvent ratio, time of preparation, and solvent were studied. MOL decoctions and infusions, commonly prepared at home, were better or of equal nutritional value to preparations upon ultrasounds or maceration concerning the studied parameters. Aqueous MOL preparations were richer in total phenols (704–1949 mg per 250 mL) and the examined macroelements (1.1–2.9, 30.5–288.4 and 50.1–176.1 mg Na, K and Ca per 250 mL, respectively) and showed better antioxidant activity compared to ethanol counterparts. The 25% w/v hydroethanolic MOL preparations, suitable for consumption, presented a significant content in phenolic antioxidants and in the examined minerals, too. MOL infusions were significantly richer in total phenols with respective chamomile and olive leaf ones, comparatively examined. Overall acceptance scores of aqueous MOL preparations indicated that bitterness has to be masked for efficient reception by the consumers. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessArticle
Effect of Supercritical Fluid Extraction Process on Chemical Composition of Polianthes tuberosa Flower Extracts
Processes 2019, 7(2), 60; https://doi.org/10.3390/pr7020060 - 23 Jan 2019
Cited by 1
Abstract
Supercritical fluid extracts from flowers of Polianthes tuberosa var. double were ob tained using carbon dioxide as a solvent. Yield extract obtained was 2.5%. The effects of the pressure process (18 MPa, 28 MPa, and 38 MPa) and temperature process (313 K, 323 [...] Read more.
Supercritical fluid extracts from flowers of Polianthes tuberosa var. double were ob tained using carbon dioxide as a solvent. Yield extract obtained was 2.5%. The effects of the pressure process (18 MPa, 28 MPa, and 38 MPa) and temperature process (313 K, 323 K, and 333 K) on the volatile composition of tuberose flowers extracts were evaluated, and a significant variation in chemical composition was found. Characteristic compounds of tuberose as methyl isoeugenol, benzyl benzoate, methyl anthranilate, pentacosene, and heptacosene were obtained mainly at 18 MPa and 333 K process conditions, and could be used in the perfume or fragrance industry. Components such as geraniol, farnesol, and methyl eugenol were also obtained, these extracts could be used in the development of cosmeceutical products. This work allowed to identification of the chemical composition profile and evaluation of the changes in tuberose extracts due to the extraction process. Full article
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Open AccessArticle
The Study on Extraction Process and Analysis of Components in Essential Oils of Black Pepper (Piper nigrum L.) Seeds Harvested in Gia Lai Province, Vietnam
Processes 2019, 7(2), 56; https://doi.org/10.3390/pr7020056 - 22 Jan 2019
Cited by 30
Abstract
Black pepper (Piper nigrum L.) is a tropical crop with extensive medicinal potential in ethnomedicine and nutraceutical applications. The essential oil of black pepper finds wide applications in inhabitation of respiratory infections and soothing of muscular pains due to its warming and [...] Read more.
Black pepper (Piper nigrum L.) is a tropical crop with extensive medicinal potential in ethnomedicine and nutraceutical applications. The essential oil of black pepper finds wide applications in inhabitation of respiratory infections and soothing of muscular pains due to its warming and energizing property. The pungent bioactive piperine is responsible for this function, and therefore, efficient technology is required for an optimal extraction process of this compound. In the present article, we have developed a procedure for extracting black pepper essential oil from Vietnam, optimizing conditions that affect the extraction process. The effect of process parameters, namely material size, preservation method, the concentration of sodium chloride, the concentration of soak time, the ratio of material to water, temperature extraction, time extraction on the extraction yield, and relative efficiency were investigated. Results demonstrated that 20 g of black pepper milled with a mesh size of 160 obtained 0.48 g of essential oil (2.4%) at a raw material to water ratio of 1/21 (g/mL) at 150 °C in a time of 5.2 h. GC-MS (Gas chromatography–mass spectrometry) spectra showed that 3-carene (29.21%), D-limonene (20.94%), caryophyllene (15.05%), and β-pinene (9.77%) were present as major components. These results suggested that the essential oil extracted from Vietnamese black pepper is applicable in the manufacturing processes of insecticides and air deodorizers. Full article
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Open AccessArticle
Pilot Plant Data Assessment in Anaerobic Digestion of Organic Fraction of Municipal Waste Solids
Processes 2019, 7(1), 54; https://doi.org/10.3390/pr7010054 - 21 Jan 2019
Cited by 8
Abstract
In this paper, a preliminary study of anaerobic digestion of organic fraction of municipal solid wastes (OFMSW) in presented with the aim to compare the performances of both wet- and dry-type reactors. The treatment of OFMSW via anaerobic digestion (AD) producing biogas is [...] Read more.
In this paper, a preliminary study of anaerobic digestion of organic fraction of municipal solid wastes (OFMSW) in presented with the aim to compare the performances of both wet- and dry-type reactors. The treatment of OFMSW via anaerobic digestion (AD) producing biogas is a process that is receiving a growing interest because two different needs can be coupled: the request of sustainable municipal waste treatments and increasing demand renewable energy. This paper aims to offer experimental results comparing batch test and continuous experimental reactors under different conditions of humidity and solid content. Results show that both the investigated configurations may be used for converting OFMSW into a high quality biogas and that the increase of dry matter in the continuous process still allows to achieve significant biogas production rates. A slight reduction of the methane content was observed (less than 5% relative) that can be also related to the change in the level of volatile fatty acids. These results are very promising in supporting the possibility of operating an industrial scale plant with a dry-process without affecting the system performance. Full article
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Open AccessArticle
Ultrasonic-Assisted Extraction and Swarm Intelligence for Calculating Optimum Values of Obtaining Boric Acid from Tincal Mineral
Processes 2019, 7(1), 30; https://doi.org/10.3390/pr7010030 - 10 Jan 2019
Cited by 1
Abstract
The objective of this study is to focus on boric acid extraction from the mineral tincal, in order to determine the optimum conditions thanks to the ultrasonic-assisted extraction (UAE) technique (with the response surface methodology (RSM) for the first time), and artificial intelligence [...] Read more.
The objective of this study is to focus on boric acid extraction from the mineral tincal, in order to determine the optimum conditions thanks to the ultrasonic-assisted extraction (UAE) technique (with the response surface methodology (RSM) for the first time), and artificial intelligence based swarm intelligence. Characterization of the tincal were done by using thermo-gravimetric assay (TG-DTA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. In detail, a central composite design (CCD) was used for determining the effects of different solvent/solid ratios, pH, extraction time, and extraction temperature on the yield, which was determined by the conductometric method. The optimum values regarding the best extraction process was calculated by using five different swarm intelligence techniques: Particle swarm optimization (PSO), cuckoo search (CS), genetic algorithms (GA), Differential evolution (DE), and the vortex optimization algorithm (VOA). In the study content, technical details regarding to background and applied experimental processes are given and the findings pointing an approximate 85–92% boron extraction from tincal ore are discussed generally. Full article
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Open AccessArticle
A Green Process for the Extraction and Purification of Hesperidin from Mexican Lime Peel (Citrus aurantifolia Swingle) that is Extendible to the Citrus Genus
Processes 2018, 6(12), 266; https://doi.org/10.3390/pr6120266 - 15 Dec 2018
Cited by 3
Abstract
The processing of Mexican limes generates great amounts of peel as a by-product. Lime peel is mainly rich in the flavonoid hesperidin, whose bioactivity is oriented mainly to cardiovascular diseases and cancer. The purpose of this work was to develop a green process [...] Read more.
The processing of Mexican limes generates great amounts of peel as a by-product. Lime peel is mainly rich in the flavonoid hesperidin, whose bioactivity is oriented mainly to cardiovascular diseases and cancer. The purpose of this work was to develop a green process for the extraction and purification of hesperidin from Mexican lime peel. The extraction of hesperidin was investigated on a laboratory scale by varying the solvent composition and the solid-to-solvent ratio, and then scaling this process (volume: 20 L). Next, a purification process using adsorption resins was assessed: first through static tests to determine the adsorption efficiency with two resins (FPX66, EXA118), and then on a packed column with 80 mL of resin at 25 °C. Lab-scale extraction showed that the best conditions were a solid-to-solvent ratio of 0.33 g/mL and 60% ethanol. After using these conditions at pilot scale and concentrating the solution, the hesperidin content of the extract was 0.303 mg/mL. Through static tests, higher adsorption efficiencies were achieved with the EXA-118 resin and diluted extract (4:6 ratio with 10% dimethylsulfoxide, (DMSO)). Finally, the purification process on a packed column from the diluted extract (hesperidin concentration of 0.109 mg/mL) had a mean recovery efficiency of almost 90%. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Review

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Open AccessReview
Overview of Alternative Ethanol Removal Techniques for Enhancing Bioethanol Recovery from Fermentation Broth
Processes 2019, 7(7), 458; https://doi.org/10.3390/pr7070458 - 17 Jul 2019
Cited by 2
Abstract
This study aims at reviewing the alternative techniques for bioethanol recovery, highlighting its advantages and disadvantages, and to investigate the technical challenges facing these alternatives to be widely used. The findings showed that the integration of these techniques with the fermentation process did [...] Read more.
This study aims at reviewing the alternative techniques for bioethanol recovery, highlighting its advantages and disadvantages, and to investigate the technical challenges facing these alternatives to be widely used. The findings showed that the integration of these techniques with the fermentation process did not meet a large acceptance in the industrial sector. The majority of conducted studies were mainly focusing on ethanol recovery from aqueous standard solution rather than the investigation of these techniques performance in fermentation-separation coupled system. In this context, pervaporation has received more attention as a promising alternative to distillation. However, some challenges are facing the integration of these techniques in the industrial scale as the fouling problem in pervaporation, the toxicity of solvent in liquid extraction, energy consumption in vacuum fermentation. It was also found that there is a lack of the technical economic analysis for these techniques which may limit the spread of its application in the large scale. Currently, hybrid systems integrating distillation with other alternative techniques are considered as an innovative solution to reduce the high cost of the distillation process and the low separation efficiency of the alternatives techniques. Full article
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Open AccessFeature PaperReview
The Flotation Process Can Go Green
Processes 2019, 7(3), 138; https://doi.org/10.3390/pr7030138 - 06 Mar 2019
Cited by 7
Abstract
In today’s world of environmental strain, wastewater treatment has become a, more or less, conventional application of flotation—as for instance, in the oil, food, or chemical industries, and in potable water treatment. In this paper, different flotation methods (such as ion, adsorbing colloid, [...] Read more.
In today’s world of environmental strain, wastewater treatment has become a, more or less, conventional application of flotation—as for instance, in the oil, food, or chemical industries, and in potable water treatment. In this paper, different flotation methods (such as ion, adsorbing colloid, and adsorptive flotation, including biosorption) and techniques will be reviewed; and, in order to explain them further, several applications of these from the laboratory (General and Inorganic Chemical Technology) at Aristotle University of Thessaloniki, Greece (AUTh) will be presented and analyzed, with the main focus on sustainability. The application of flotation as a separation process, when applied in pollution control or during water treatment, was often criticized due to the possible toxicity of the applied collectors; however, the use of biosurfactants may alleviate this concern and enhance its further acceptability. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessFeature PaperProject Report
Applied Cleaning Methods of Oil Residues from Industrial Tanks
Processes 2020, 8(5), 569; https://doi.org/10.3390/pr8050569 - 11 May 2020
Abstract
The oil industry is facing a major problem with the large amount of oil residue generated in the tanks that store and process crude oil or its products. Research has shown that the residues of petroleum sludge, which according to a sample from [...] Read more.
The oil industry is facing a major problem with the large amount of oil residue generated in the tanks that store and process crude oil or its products. Research has shown that the residues of petroleum sludge, which according to a sample from the Azzawiya oil refinery in Libya mainly consist of oil, water and solid residues in 42.8%, 2.9% and 55.2% respectively, result in the alteration of the product quality and reduced capacity of the tanks. The solution for this problem as well as the need for inspection and maintenance requires the removal of this oil sludge and the internal cleaning of the tanks. This report aims to review the applied clean-up methods available in the world market and to identify the most efficient, safest, most economical and most environmentally friendly cleaning process. It must be noted that until now, there is not any published work which presents the applied techniques. To accomplish this goal, a total of five manual, automatic and robotic cleaning systems were analyzed and evaluated according to their advantages and disadvantages. The results show that the MEGAMACS with sludge extractor automatic cleaning system with an output of 14.8 m3/h is the fastest cleaning system, while the MARTin where the presence of people inside the tank is not necessary at any stage is the safest. In terms of cleaning costs and environmental impact, the automated BLABO, COW and MEGAMACS systems as well as the MARTin robotic system are the most economical and environmentally friendly due to the closed cleaning circuit and the ability to recover up to 95% of the oil from the sludge, which is returned to the customer and the earnings cover the costs of cleaning. The conclusion drawn is that the current need in the oil industry, in the field of tank cleaning, is the use of high-efficiency automatic or robotic cleaning methods, which aim to reduce the tank downtime, without the need for staff entrance into a permit-required confined space and with the ability to recover up to 100% of the hydrocarbons present in the composition of the sludge. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessCase Report
Application of Supergravity Technology in a TEG Dehydration Process for Offshore Platforms
Processes 2019, 7(1), 43; https://doi.org/10.3390/pr7010043 - 15 Jan 2019
Cited by 1
Abstract
In the dehydration process of offshore natural gas production, due to the site limitation of the platform, if the conventional triethylene glycol (TEG) dehydration process is employed, the size of the absorption tower is usually small. However, in the case of fluctuations in [...] Read more.
In the dehydration process of offshore natural gas production, due to the site limitation of the platform, if the conventional triethylene glycol (TEG) dehydration process is employed, the size of the absorption tower is usually small. However, in the case of fluctuations in raw material gas and large gas production, it is easy to cause a large loss of TEG and a flooding event, resulting in the water dew point of natural gas not meeting the requirements. Therefore, combined with the dehydration process of TEG and supergravity technology, a new dehydration process of natural gas suitable for offshore platforms is proposed in this paper. The principle and process of the TEG dehydration process based on supergravity technology are discussed by establishing a mass transfer model. The laboratory experiment of the new process is carried out, and the effects of TEG flow rate, super-gravity packed bed rotation speed, and gas flow rate on the air dew point are obtained. By studying the dewatering balance of the rotating packed bed in the improved process, it is proved that the dewatering performance of the high gravity machine (Higee) is much better than that of the ordinary tower dewatering equipment. Through field experiments, the dewatering effect of continuous operation and sudden changes in working conditions is obtained, indicating that the Higee can completely replace the traditional tower equipment for natural gas dehydration. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Author: Dr. Nurulwahidah Fauzi <[email protected]>
Affiliation: Nurulwahidah Fauzi Senior Lecturer, Faculty of Quranic and Sunnah Studies, Islamic Science University of Malaysia, 71800 Nilai, Negeri Sembilan, Malaysia.

Author: Dr. Kangling Zhu <[email protected]>
Affiliation: School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, China
Title: Purification of Flavonoid from Mulberry Leaf by High Speed Counter-Current Chromatography

Author: Dr. Antonios Papadopoulos<[email protected]>
Title: Green lignocellulosic raw material as absorbent for oil removal

Author: Prof. Petridis Dimitrios <[email protected]>
Title: Alexander Technological Educational Institute of Thessaloniki (A.T.E.I.Th.), Department of Food Technology, GREECE

 

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