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Separations, Volume 10, Issue 4 (April 2023) – 51 articles

Cover Story (view full-size image): Airborne submicron oil droplets (oil mists) often occur as undesired contaminants in industrial applications and have to be removed to prevent air pollution or grant health protection at workplaces. In industry, these oil mists are separated by coalescence filters.
The separated oil can take different shapes on the filter and may influence the separation efficiency. As filtration velocities can vary in industrial applications, the impact on the gas velocity on these separated structures needs to be characterized. Utilizing a µ-CT, oil deposits are quantified and compared at three application-orientated filtration velocities. The results indicate that there is no influence of the filtration velocity on the local oil distribution. It is assumed that the oil structures formed by coalescence are dominated by the wetting properties of the fibers. View this paper
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Communication
Detection of Periodontal Pathogens Based on an Integrated Continuous Flow PCR and Capillary Electrophoresis Microfluidic Chip
Separations 2023, 10(4), 271; https://doi.org/10.3390/separations10040271 - 21 Apr 2023
Viewed by 536
Abstract
Continuous-flow PCR (CF-PCR) can realize rapid DNA amplification because of the high temperature variation rate. However, off-line detection methods for PCR may induce cross contamination. To overcome this problem, we herein fabricated an integrated CF-PCR and electrophoresis microfluidic chip. The optimal voltage applied [...] Read more.
Continuous-flow PCR (CF-PCR) can realize rapid DNA amplification because of the high temperature variation rate. However, off-line detection methods for PCR may induce cross contamination. To overcome this problem, we herein fabricated an integrated CF-PCR and electrophoresis microfluidic chip. The optimal voltage applied in the electrophoresis part of the microfluidic chip was achieved by simulation in COMSOL. Coating the inside wall of the microchannel can inhibit electroosmotic flow and improve the resolution for DNA fragments. The temperature distribution of the serpentine part can meet the PCR and has no obvious suppressive effect on sample separation. Finally, we have performed the amplification of target genes for Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola and detected the corresponding PCR products in the microfluidic chip within 11 min. Such work provides a new method for the rapid detection of bacteria. Full article
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Article
Phenolic Profile of Castanea Bee Pollen from the Northwest of the Iberian Peninsula
Separations 2023, 10(4), 270; https://doi.org/10.3390/separations10040270 - 21 Apr 2023
Viewed by 638
Abstract
Bee pollen is a rich bee product, from the point of view of its nutritional and functional chemical characteristics. The chemical composition of bee pollen and its properties make this product an excellent food supplement for the human diet, due to its various [...] Read more.
Bee pollen is a rich bee product, from the point of view of its nutritional and functional chemical characteristics. The chemical composition of bee pollen and its properties make this product an excellent food supplement for the human diet, due to its various functional bioactivities, such as having antioxidant, antibacterial, antifungal, and anti-inflammatory properties. These properties depend on the botanical origin of the bee pollen. Castanea sativa bee pollen is one of the most important types of pollen collected in the northwest of the Iberian Peninsula. Thus, the phenolic profile of Castanea bee pollen was featured in this study. For this, 11 samples of Castanea were selected through prior colorimetric separation using the CIELab* scale and verified with palynological analysis. Identification of the main phenol compounds was performed through LC/DAD/ESI-MSn analysis. The phenols compounds were quantified using calibration curves for caffeic acid, quercetin, and naringenin. The main results showed a profile formed of 19 compounds for all samples, although quantitative differences were found. Most of these compounds were phenolamides, with N1, N5, and N10-tricaffeoylspermidine being significantly (p < 0.05) the most abundant. Three isorhamnetin glycoside derivatives and one naringenin were also identified. The richness in phenolamides of Castanea bee pollen identified in this study suggests Castanea bee pollen as a functional food, owing to its healthy properties. Full article
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Article
Zero Liquid Discharge and Resource Treatment of Low-Salinity Mineralized Wastewater Based on Combing Selectrodialysis with Bipolar Membrane Electrodialysis
Separations 2023, 10(4), 269; https://doi.org/10.3390/separations10040269 - 21 Apr 2023
Viewed by 751
Abstract
A large amount of mine water is generated during coal production, which not only damages the surface environment and ecology but also wastes groundwater resources in the mining area, exacerbating regional water scarcity. In this work, a novel zero liquid discharge technology combining [...] Read more.
A large amount of mine water is generated during coal production, which not only damages the surface environment and ecology but also wastes groundwater resources in the mining area, exacerbating regional water scarcity. In this work, a novel zero liquid discharge technology combining selectrodialysis (SED) and bipolar membrane electrodialysis (BMED) was developed for the resourceful treatment of low-salinity mineralized wastewater. The SED stack had demonstrated to be workable for the elimination of multivalent ions. The BMED stack converts brine into acid and base. After SED, a high pure crude salt (~98%) was attained. Furthermore, under the conditions of a current density of 20 mA/cm2, a flow velocity of 20 L/h, and an initial acid/base concentration of 0.10 mol/L, the maximum concentrations of acid and base were found to be 0.75 mol/L and 0.765 mol/L, respectively, for a feed conductivity of 55 mS/cm. The cost of the entire electrodialysis stage was evaluated to be USD 1.38/kg of NaOH. Therefore, this combined UF-RO-SED-BMED process may be an effective strategy for the sustainable treatment of low-salinity mineralized wastewater. Full article
(This article belongs to the Special Issue Application of Membrane Materials and Membrane Separation Technology)
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Article
Quantification of Health Claim-Relevant Tyrosol and Hydroxytyrosol after Direct Hydrolysis Improves Customer Understanding and Mitigates Market Distortion
Separations 2023, 10(4), 268; https://doi.org/10.3390/separations10040268 - 21 Apr 2023
Viewed by 843
Abstract
The EFSA-approved claim that olive oil is beneficial for cardiovascular health suffers from ambiguities that lead to a vague and potentially subjective interpretation of the underlying analytical data. Misunderstandings among customers, but also market distortions are possible consequences. In this study, a rapid [...] Read more.
The EFSA-approved claim that olive oil is beneficial for cardiovascular health suffers from ambiguities that lead to a vague and potentially subjective interpretation of the underlying analytical data. Misunderstandings among customers, but also market distortions are possible consequences. In this study, a rapid and simple analytical technique is presented that circumvents the ambiguity by measuring levels of putative health-promoting compounds as the equivalent of tyrosol and hydroxytyrosol, cleaving such moieties from more complex constituents such as oleuropein and oleocanthal. Since the direct hydrolysis of the olive oil is the central element of the process, the reaction temperature, time, reagent concentration and reagent type were optimized. In addition, the influence of co-solvents, which might support the intermittent miscibility of the two phases during hydrolysis, was investigated. The analytical and economic implications are discussed particularly in the context of a commonly used technique. Full article
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Article
CFD Simulation and Optimal Design of a New Parabolic–Shaped Guided Valve Tray
Separations 2023, 10(4), 267; https://doi.org/10.3390/separations10040267 - 20 Apr 2023
Viewed by 572
Abstract
A new parabolic–shaped guided valve tray is proposed. The gas–liquid two–phase flow of parabolic and conventional rectangular guided valve trays is simulated using the computational fluid dynamics (CFD) method. The clear liquid height on the tray was predicted for different combinations of the [...] Read more.
A new parabolic–shaped guided valve tray is proposed. The gas–liquid two–phase flow of parabolic and conventional rectangular guided valve trays is simulated using the computational fluid dynamics (CFD) method. The clear liquid height on the tray was predicted for different combinations of the superficial gas velocity, liquid flow intensity and weir height. The predicted values were in good agreement with the calculated ones. The parabolic–shaped guided valve tray has a more uniform flow form by comparing the gas–liquid two–phase flow behavior of parabolic and rectangular guided valve trays: the liquid level difference is slight, the guiding effect is strong, and the re–mixing phenomenon is improved. Further modeling and simulations were conducted for nine parabolic–shaped guided valve trays of different function expressions. The optimum valve structure is the parabolic–shaped guided valve of the a–value at 0.075 and the t–value at 26. Full article
(This article belongs to the Special Issue Advances in Separation Engineering)
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Article
Comparison of Adsorbents for Cesium and Strontium in Different Solutions
Separations 2023, 10(4), 266; https://doi.org/10.3390/separations10040266 - 19 Apr 2023
Viewed by 399
Abstract
Adsorption is an effective method to remove cesium and strontium from a solution. Although a variety of adsorbents has been reported, it is difficult to compare their adsorption properties due to different experimental conditions (such as solution concentration, volume, composition, temperature, etc.). In [...] Read more.
Adsorption is an effective method to remove cesium and strontium from a solution. Although a variety of adsorbents has been reported, it is difficult to compare their adsorption properties due to different experimental conditions (such as solution concentration, volume, composition, temperature, etc.). In this paper, a series of adsorbents for the adsorption of cesium and strontium (ammonium phosphomolybdate, Prussian blue, sabite, clinoptilolite, titanium silicate) were synthesized and characterized using XRD, IR and SEM, and their adsorption performance in mixed solution (containing Li, Na, K, Cs, Ca, Sr and Mg ions, 1 mmol L−1), artificial seawater and salt lake brine were studied under the same conditions; in addition, the adsorption mechanism was elucidated. The results showed that ammonium phosphomolybdate has the largest adsorption capacity for cesium in the mixed solution. In artificial seawater and salt lake brine, Prussian blue displays the highest cesium adsorption capacity and the best selectivity. The multi-adsorption mechanisms are beneficial to the selective adsorption of Prussian blue in complex solutions. These results are useful for choosing adsorbents for cesium and strontium in applications. Full article
(This article belongs to the Special Issue Separations of Metals and Radionuclide from Water)
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Article
Experimental Study on Synergistic Extraction for Separating Manganese and Iron from Waste Ternary Battery Leaching Solution
Separations 2023, 10(4), 265; https://doi.org/10.3390/separations10040265 - 19 Apr 2023
Viewed by 433
Abstract
In this paper, the key factors and the mechanism of the extraction of iron and manganese from the sulfuric acid leaching solution of waste ternary lithium-ion batteries were studied by combining P204 and N235 extractors. The experimental results showed that the optimal organic [...] Read more.
In this paper, the key factors and the mechanism of the extraction of iron and manganese from the sulfuric acid leaching solution of waste ternary lithium-ion batteries were studied by combining P204 and N235 extractors. The experimental results showed that the optimal organic phase composition was 25% P204 + 15% N235 + 60% sulfonated kerosene, and the optimal pH of the pre-extraction solution was in the range of 3.0–3.5. Under the conditions of an extraction temperature of 25–35 °C and an extraction ratio of O/A = 1/1 and after mixing for 5 min, the removal rate of Mn and Fe exceeded 99%. Under the same extraction conditions, the extraction effect of the P204-N235 composite extractant on Mn and Fe was better than that of P204 alone. logD-log[P204] showed that the formulas of the Mn and Fe extracts were MnR2(HR) and FeR2(HR), respectively. The logD-pH diagram showed that only one free H+ was released for each metal ion during extraction, and extraction occurred via a cation exchange reaction. Full article
(This article belongs to the Special Issue Advanced Methods for Recovery of Valuable Metals from Waste)
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Review
Mass Transfer and Droplet Behaviors in Liquid-Liquid Extraction Process Based on Multi-Scale Perspective: A Review
Separations 2023, 10(4), 264; https://doi.org/10.3390/separations10040264 - 18 Apr 2023
Viewed by 871
Abstract
Liquid-liquid extraction is an important separation technology in the chemical industry, and its separation efficiency depends on thermodynamics (two-phase equilibrium), hydrodynamics (two-phase mixing and contact), and mass transfer (molecular diffusion). For hydrodynamics, the dispersion size of droplets reflects the mixing of two phases [...] Read more.
Liquid-liquid extraction is an important separation technology in the chemical industry, and its separation efficiency depends on thermodynamics (two-phase equilibrium), hydrodynamics (two-phase mixing and contact), and mass transfer (molecular diffusion). For hydrodynamics, the dispersion size of droplets reflects the mixing of two phases and determines the mass transfer contact area of the two phases. Therefore, a deep understanding of the droplet dispersion mechanism can help guide process intensification. The mass transfer and droplet behaviors in the liquid-liquid extraction process are reviewed based on three scales: equipment, droplets, and the interface between two liquids. Studies on the interaction between mass transfer and other performance parameters in extraction equipment as well as liquid-liquid two-phase flow models are reviewed at the equipment scale. The behaviors of droplet breakage and coalescence and the kernel function of the population balance equation are reviewed at the droplet scale. Studies on dynamic interfacial tension and interaction between interfaces are reviewed at the interface scale. Finally, the connection among each scale is summarized, the existing problems are analyzed, and some future research directions are proposed in the last section. Full article
(This article belongs to the Special Issue Advances in Separation Engineering)
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Article
Influence of Season and Habitat on the Essential Oils Composition, Allelopathy, and Antioxidant Activities of Artemisia monosperma Delile
Separations 2023, 10(4), 263; https://doi.org/10.3390/separations10040263 - 17 Apr 2023
Viewed by 477
Abstract
Plants belonging to the Artemisia genus (Asteraceae) are widely distributed worldwide and have many ethnopharmacological, traditional, therapeutic, and phytochemical aspects. Artemisia monosperma is an important aromatic plant due to its traditional and therapeutic uses and phytochemical diversity, including essential oils (EOs). The EO chemical [...] Read more.
Plants belonging to the Artemisia genus (Asteraceae) are widely distributed worldwide and have many ethnopharmacological, traditional, therapeutic, and phytochemical aspects. Artemisia monosperma is an important aromatic plant due to its traditional and therapeutic uses and phytochemical diversity, including essential oils (EOs). The EO chemical profile of aromatic plants has been reported to be affected by exogenous and endogenous factors. Geographic and seasonal variations are crucial factors shaping the chemical composition of the EO. Herein, the variations of the yields, chemical profiles, and allelopathic and antioxidant activities of A. monosperma EOs collected from three regions in four seasons were assessed. A slight variation in the oil yields was observed among regions and seasons, while the chemical profile, characterized via GC-MS, exhibited significant quantitative and qualitative variation among either regions or seasons. Sesquiterpenes were the main components of all EOs, with significant variation in concentration. In most EO samples, the summer-plant samples had the highest concentration of sesquiterpenes, followed by spring, winter, and autumn. The 7-epi-trans-sesquisabinene hydrate, 6-epi-shyobunol, dehydro-cyclolongifolene oxide, isoshyobunone, diepicedrene-1-oxide, dehydro-aromadendrene, and junipene were the main compounds of all the EO samples. The extracted EOs of the A. monosperma samples showed considerable allelopathic activity against the weed Dactyloctenium aegyptium and the crop Lactuca sativa. A significant variation in allelopathic activity was observed among samples collected during different seasons, while the samples of the autumn and summer seasons had more potential. Also, L. sativa was more affected by the EO compared to D. aegyptium, reflecting that weeds are more resistant to allelochemicals. In this context, the EOs of A. monosperma samples exhibited substantial antioxidant activity with the same pattern of allelopathic activity, whereas the samples of the autumn and summer seasons showed higher antioxidant activity. These biological activities of the EOs could be ascribed to the higher content of oxygenated compounds. The present study revealed that seasons have a substantial effect on EO production as well as composition. In consequence, the biological activities varied with the variation of the chemical profile of the EO. These results show the importance of season/timing for sampling aromatic plants. Full article
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Article
A Fixed-Bed Column with an Agro-Waste Biomass Composite for Controlled Separation of Sulfate from Aqueous Media
Separations 2023, 10(4), 262; https://doi.org/10.3390/separations10040262 - 17 Apr 2023
Viewed by 741
Abstract
An agro-waste composite with a pelletized form was prepared and characterized via IR and 13C solids NMR spectroscopy. Thermal gravimetry analysis (TGA) was used to study the weight loss profiles, while SEM images provided insight on the biocomposite morphology, along with characterization [...] Read more.
An agro-waste composite with a pelletized form was prepared and characterized via IR and 13C solids NMR spectroscopy. Thermal gravimetry analysis (TGA) was used to study the weight loss profiles, while SEM images provided insight on the biocomposite morphology, along with characterization of the sulfate adsorption properties under equilibrium and dynamic conditions. The sulfate monolayer adsorption capacity (qe = 23 mg/g) of the prepared agro-waste pellets was estimated from the adsorption isotherm results by employing the Langmuir model, and comparable fitting results were obtained by the Freundlich model. The dynamic adsorption properties were investigated via adsorption studies with a fixed bed column at pH 5.2. The effects of various parameters, including flow rate, bed height and initial concentrations of sulfate, were evaluated to estimate the optimal conditions for the separation of sulfate. The experimental data of the breakthrough curves were analyzed using the Thomas and Yoon–Nelson models, which provided satisfactory best-fits for the fixed bed kinetic adsorption results. The predicted adsorption capacities for all samples according to the Thomas model concur with the experimental values. The optimum conditions reported herein afford the highest dynamic adsorption capacity (30 mg/g) as follows: 1100 mg/L initial sulfate concentration, 30 cm bed height and 5 mL/min flow rate. The breakthrough time was measured to be 550 min. This study contributes to a strategy for controlled separation of sulfate using a sustainable biocomposite material that is suitable for fixed-bed column point-of-use water treatment systems. Full article
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Article
Synthesis of Isoreticular Metal Organic Framework-3 (IRMOF-3) Porous Nanostructure and Its Effect on Naphthalene Adsorption: Optimized by Response Surface Methodology
Separations 2023, 10(4), 261; https://doi.org/10.3390/separations10040261 - 17 Apr 2023
Viewed by 792
Abstract
Naphthalene is a carcinogenic compound and its environmental release poses a major risk to human and aquatic health. Therefore, the application of nanomaterial technologies for naphthalene removal from wastewater has attracted significant attention. In this research, for the first time, the performance of [...] Read more.
Naphthalene is a carcinogenic compound and its environmental release poses a major risk to human and aquatic health. Therefore, the application of nanomaterial technologies for naphthalene removal from wastewater has attracted significant attention. In this research, for the first time, the performance of IRMOF-3 for naphthalene removal from aqueous media is evaluated. IRMOF-3 with a specific surface area of 718.11 m2·g−1 has the ability to absorb naphthalene from synthetic wastewater to a high extent. The structures and morphology of IRMOF-3 were determined by FT-IR, XRD, SEM and BET analyses. Thirty adsorption experiments were conducted to obtain the best conditions for naphthalene removal. An optimum naphthalene removal efficiency of 80.96% was obtained at IRMOF-3 amounts of 0.1 g·L−1, a solution concentration of 15 mg·L−1, a contact time of 60 min and a pH = 11. The results indicate that the lower the concentration of naphthalene, the higher its dispersion at the surface of the porous nanostructure. Increasing naphthalene concentration results in its accumulation on porous nanostructures that clog cavities. In addition, high contact time provides ample opportunity for naphthalene to penetrate the cavities and pores which facilitates crystallization phenomena deep in the pores. Finally, the results of this study revealed that IRMOF-3 is one of the most effective adsorbents for naphthalene removal from wastewater. Full article
(This article belongs to the Special Issue Emerging Composite Materials for Environmental Pollutants Removal)
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Article
Adsorption of Chromium (VI) from Aqueous Solution Using Palm Leaf-Derived Biochar: Kinetic and Isothermal Studies
Separations 2023, 10(4), 260; https://doi.org/10.3390/separations10040260 - 17 Apr 2023
Viewed by 693
Abstract
In this study, biochar produced by low-temperature pyrolysis from palm leaves was treated with phosphoric acid in order to increase the sorption efficiency of Cr (VI) from aqueous solutions. Numerous characterization experiments using BET surface area, FE-SEM and FT-IR showed that the phosphoric [...] Read more.
In this study, biochar produced by low-temperature pyrolysis from palm leaves was treated with phosphoric acid in order to increase the sorption efficiency of Cr (VI) from aqueous solutions. Numerous characterization experiments using BET surface area, FE-SEM and FT-IR showed that the phosphoric acid-treated biochar (TBC-P) was covered with P particles. In comparison to the palm leaves and biochar, the TBC-P also had more surface oxygenated functional groups, surface area, pore size and internal structure. FTIR analysis showed that the functional groups of pretreated biochar were similar to those of biochar. Batch adsorption experiments showed that the TBC-P had a strong sorption ability to Cr (VI), with the highest removal efficiency of 99% at a low pH value of 2.0, which was significantly higher than that of the untreated biochar. The kinetic study has shown that the mechanism of the reaction was well represented by the second-order model, while isotherm data were well presented by the Langmuir model. The TBC-P was successfully regenerated using a 0.1 M HCl solution. Full article
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Article
Study on Pyrolysis Pretreatment Characteristics of Spent Lithium-Ion Batteries
Separations 2023, 10(4), 259; https://doi.org/10.3390/separations10040259 - 17 Apr 2023
Viewed by 716
Abstract
In recent years, the rapid development of the new energy vehicle industry has led to an increase in the production of used lithium-ion batteries. The recycling of waste lithium-ion batteries is expected to alleviate the shortage of valuable metals in battery materials. The [...] Read more.
In recent years, the rapid development of the new energy vehicle industry has led to an increase in the production of used lithium-ion batteries. The recycling of waste lithium-ion batteries is expected to alleviate the shortage of valuable metals in battery materials. The electrode material is adhered to the collector by a viscous organic binder such as PVDF. A key step in recycling is to separate the anode material and aluminum foil from the waste lithium batteries to obtain materials rich in valuable metals. Compared with chemical dissolution and decomposition, pyrolysis pretreatment is a simple and feasible method. By reducing the binding force between the binder and the positive active substance at a high temperature, organic matter can be eliminated by thermal decomposition at a high temperature. At the same time, the organic component of PVDF has a high calorific value, and the energy can be recycled and reused, which can save energy. The pyrolysis process and pyrolysis behavior of spent LIBs materials were studied in this paper. FWO, Friedman and KAS conversion methods were spent to compare the pyrolysis kinetics of positive electrode materials. Thermogravimetric analysis shows that the cathode material is decomposed into three stages with mass losses of 1.7%, 1.2% and 3.3%, respectively. The activation energy (Eα) calculated by the three model-free methods is best fitted by the FWO method. During the pyrolysis process, the concentration of F decreases gradually with the increase in temperature, and the concentrations of Ni, Mn, Co and Li remain stable. Most of the harmful element (F) in spent LIBs is converted into HF gas, which can be adsorbed by alkaline solution. The analysis of pyrolysis kinetics and pyrolysis products is of great significance for large-scale pretreatment of spent lithium-ion batteries. Full article
(This article belongs to the Special Issue Advanced Methods for Recovery of Valuable Metals from Waste)
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Article
Characterization and Photocatalytic Performance of Newly Synthesized ZnO Nanoparticles for Environmental Organic Pollutants Removal from Water System
Separations 2023, 10(4), 258; https://doi.org/10.3390/separations10040258 - 16 Apr 2023
Viewed by 703
Abstract
Most countries are facing problems of environmental pollution due to toxic organic pollutants being discharged into the environment from various man-made sources. Heterogeneous photocatalysis is a possible solution for the mentioned problem, and it has been widely applied for the removal of pollutants [...] Read more.
Most countries are facing problems of environmental pollution due to toxic organic pollutants being discharged into the environment from various man-made sources. Heterogeneous photocatalysis is a possible solution for the mentioned problem, and it has been widely applied for the removal of pollutants from aqueous solutions, thanks to its high removal efficiency and environmental friendliness. Among the commonly used metal oxides, ZnO has attracted researchers’ interests due to its ecofriendly and nontoxic nature. In this work, ZnO nanoparticles (ZnO-NPs) were prepared by the precipitation method from water (w) and ethanol solutions of the corresponding metal precursors (zinc–acetate dihydrate, A_ZnO, and zinc–nitrate hexahydrate, N_ZnO) followed by calcination at different temperatures. The structure and morphology of the prepared catalysts were characterized by different techniques (XRD, BET, and SEM). Based on the XRD results, it can be seen that the synthesized NPs possess high purity. Furthermore, at a higher calcination temperature, a higher crystal size was observed, which was more intense in the case of the ethanol solution of the precursors. The BET analysis showed macropores at the surface and also indicated that the increased temperature led to decreased surface area. Finally, SEM images showed that in the case of the water precursor solution, an irregular, rod-like shape of the NPs was observed. The photocatalytic properties of newly synthesized ZnO-NPs exposed to simulated sunlight were examined during the removal of pesticide clomazone (CLO) and the antidepressant drug amitriptyline (AMI). ZnO-NPs prepared by the precipitation method from the water solution of zinc–acetate dihydrate and calcined at 500 °C (A_ZnOw_500) showed the highest performance under simulated sunlight. Furthermore, the activity of A_ZnOw_500 and N_ZnOw_500 catalysts in the removal of three organic pollutants from water—two pesticides (sulcotrione (SUL) and CLO) and one pharmaceutical (AMI)—was also compared. Results showed that decreased photocatalytic activity was observed in the presence of N_ZnOw_500 NPs in all investigated systems. Finally, the effect of the initial pH was also examined. It was found that in the case of CLO and SUL, there was no influence of the initial pH, while in the case of AMI the kapp was slightly increased in the range from pH ~7 to pH ~10. Full article
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Review
A Review of Liquid Chromatography-Mass Spectrometry Strategies for the Analyses of Metabolomics Induced by Microplastics
Separations 2023, 10(4), 257; https://doi.org/10.3390/separations10040257 - 16 Apr 2023
Viewed by 833
Abstract
Microplastics (MPs) (microscopic plastic particles) are defined as plastic fragments in the range of 1 to 5 mm. They are invisible and usually too small to be seen by humans but pollution by MPs has become an issue due to the rising use [...] Read more.
Microplastics (MPs) (microscopic plastic particles) are defined as plastic fragments in the range of 1 to 5 mm. They are invisible and usually too small to be seen by humans but pollution by MPs has become an issue due to the rising use of plastic products. Pollution of microscopic plastics has gained international attention in recent years and has become an important issue in the field of environmental protection, food safety, and human health. Numerous studies have reported that MPs have the potential for causing detrimental effects in various species. The focus of this mini review was on LC-MS-based metabolomics research into this issue by targeted and untargeted approaches. We also summarized biomarkers for assessing toxicity in land and aquatic species that are induced by MPs with different sizes and shapes, type of monomer, and the dose. Based on previous research results, MPs have the potential for affecting energy metabolism and the immune system, chronic inflammation, and neurotransmitter disorders in a wide variety of species. These biomarkers discovered by metabolomics are consistent with other methods, showing the reliability of LC-MS-based metabolomics. Further research is highly anticipated to explore other toxicity effects that are induced by MPs. Full article
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Article
Comparative Study of E-Nose, GC-MS, and GC-IMS to Distinguish Star Anise Essential Oil Extracted Using Different Extraction Methods
Separations 2023, 10(4), 256; https://doi.org/10.3390/separations10040256 - 16 Apr 2023
Viewed by 733
Abstract
In this study, star anise (Illicium verum) essential oils (SAEOs) were extracted by hydrodistillation (HD), ethanol solvent extraction (ESE), supercritical CO2 (SCD) and subcritical extraction (SE) via electronic nose (E-nose), gas chromatography-mass spectrometry (GC-MS), and GC-ion mobility spectrometry (GC-IMS). GC-MS [...] Read more.
In this study, star anise (Illicium verum) essential oils (SAEOs) were extracted by hydrodistillation (HD), ethanol solvent extraction (ESE), supercritical CO2 (SCD) and subcritical extraction (SE) via electronic nose (E-nose), gas chromatography-mass spectrometry (GC-MS), and GC-ion mobility spectrometry (GC-IMS). GC-MS and GC-IMS were used to identify the volatile compounds, and GC-MS was also used to determine their concentrations. Principal component analysis (PCA) and linear discriminant analysis (LDA) were used to visualise volatile compounds and differentiate samples. The results showed that anethole and limonene were the main volatile compounds in SAEOs extracted using the four methods and their components were similar, albeit in different proportions. In addition, the fingerprints of their volatile components were established via E-nose and GC-IMS analyses. In general, GC-MS, GC-IMS, and E-nose combined with PCA and LDA analysis could accurately distinguish SAEOs extracted using different extraction methods, and GC-IMS was identified as the most suitable method because of its accuracy and rapidity. Full article
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Article
Separation, Characterization and Mammal Pancreatic Lipase Inhibitory Potential of Cucumber Flower Flavonoids
Separations 2023, 10(4), 255; https://doi.org/10.3390/separations10040255 - 16 Apr 2023
Viewed by 601
Abstract
Edible flowers are a new “old” trend in modern gastronomy and healthy nutrition aimed at increasing food attractiveness and improving the consumption of beneficial phytocompounds that have valuable properties. Cucumber (Cucumis sativus L., Cucurbitaceae family) is a well-known agricultural product; it is [...] Read more.
Edible flowers are a new “old” trend in modern gastronomy and healthy nutrition aimed at increasing food attractiveness and improving the consumption of beneficial phytocompounds that have valuable properties. Cucumber (Cucumis sativus L., Cucurbitaceae family) is a well-known agricultural product; it is an important crop that is commonly used across the globe. Despite sufficient knowledge of nutrients and secondary metabolites in cucumber fruits, the use of cucumber flowers for food purposes is still understudied. In this study, the total flavonoid fraction of cucumber flowers was isolated and purified after liquid–liquid and solid-phase extraction and polyamide and Amberlite XAD-2 separation followed by high-performance liquid chromatography with photodiode array detection and electrospray ionization triple quadrupole mass spectrometric detection (HPLC–PDA–ESI–tQ–MS/MS), resulting in the detection of 47 compounds. Identified flavonoids included luteolin, apigenin, and chrysoeriol-based flavones such as C-, O-, and C,O-glycosides, most of which were detected for the first time in C. sativus. Flower extracts from ten cucumber cultivars were quantified, and isoorientin, isoorientin-4′-O-glucoside, and cucumerins B and D were predominant. The use of in vitro assay potential to inhibit mammalian pancreatic lipases was demonstrated for the C. sativus extracts. The dominant compounds were studied separately, and luteolin derivatives were determined to be responsible for the bioactivity. To the best of our knowledge, this is the first study on cucumber flowers that has shown their wide potential for use as a beneficial dietary supplement. Full article
(This article belongs to the Special Issue Isolation, Elucidation and Synthesis of Bioactive Natural Products)
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Article
Influence of the Filtration Velocity on the Local Oil Distribution of Oleophilic Coalescence Filter Media
Separations 2023, 10(4), 254; https://doi.org/10.3390/separations10040254 - 14 Apr 2023
Viewed by 380
Abstract
Fibrous nonwoven coalescence filters are commonly utilized in gas-cleaning processes to separate liquid droplets from a gas stream, e.g., oil mists. These filters are mainly composed of micro glass fibers and in some cases, small amounts of synthetic fibers. The shape of the [...] Read more.
Fibrous nonwoven coalescence filters are commonly utilized in gas-cleaning processes to separate liquid droplets from a gas stream, e.g., oil mists. These filters are mainly composed of micro glass fibers and in some cases, small amounts of synthetic fibers. The shape of the deposited oil on filter fibers of the filter media depends on several factors, including the oil saturation, wettability, roughness, diameter of the fibers and fiber arrangement. The oil deposits can take the form of, e.g., axially symmetric barrel-shaped droplets or larger structures, such as oil sails between adjacent fibers. Understanding the initial state of the coalescence filtration process and the impact of the deposited oil structures on the separation efficiency requires characterizing these structures. X-ray microtomography (µ-CT) and artificial intelligence tools for segmentation can be utilized to visualize, identify and analyze deposited oil structures in the micrometer region. To quantify and compare oil structures formed at three distinct filtration velocities (10, 25 and 40 cm s1) commonly utilized in industrial applications and one defined oil saturation of oleophilic coalescence filter media, applying X-ray microtomography is the main emphasis of this work. The results indicate that there is no significant influence of the filtration velocity on the local saturation (determined via µ-CT), the number- and volume-based fractions of the identified deposited oil structures on or between adjacent fibers as well as the droplet concentrations and distributions of deposited oil droplets. It is assumed that the structure of the deposited oil formed by coalescence in the filter medium is dominated by the wetting properties of the fibers (surface tension and surface energy) and the saturation, independent of the filtration velocity. Full article
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Article
Utilization of Waste Biomaterial as an Efficient and Eco-Friendly Adsorbent for Solid-Phase Extraction of Pantoprazole Contaminants in Wastewater
Separations 2023, 10(4), 253; https://doi.org/10.3390/separations10040253 - 14 Apr 2023
Viewed by 682
Abstract
The objective of this analysis is to establish the potential of biodegradable agro-industrial waste materials as biosorbents in the solid-phase extraction (SPE) technique for sample preparation. In this regard, waste coffee husk (CH) powder was collected, washed, treated chemically, characterized, and applied as [...] Read more.
The objective of this analysis is to establish the potential of biodegradable agro-industrial waste materials as biosorbents in the solid-phase extraction (SPE) technique for sample preparation. In this regard, waste coffee husk (CH) powder was collected, washed, treated chemically, characterized, and applied as an SPE adsorbent to extract pantoprazole from the wastewater samples. Sample detection was accomplished using the UPLC-MS/MS system. The positive mode of electrospray ionization was exploited for the ionization of the sample, and quantification of the target analyte was performed by the multiple reaction monitoring modes. The precursor to product ion transition of 384.02→1380.05 and 384.02→200.05 was used as qualifiers and quantifiers, respectively. Optimization of the particle size, adsorbent dose, and contact time were evaluated to select the best combination of features. The efficiency and regeneration capability of the CH were compared with respect to a commercially available silica-based C18 SPE adsorbent, and it was found that CH possessed comparable (~50%) extraction, as well as regeneration capacity (~95%). The developed biosorbent was applied in a wastewater sample spiked with the target analyte and recovery studies were performed, which found a range of 93.0 to 102.0% with a %RSD of 3.72 to 12.7%. Thus, CH can be exploited as a ‘greener’ replacement for the commercially available adsorbents for the extraction/retention of active pharmaceutical ingredients present in water/wastewater samples. Full article
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Article
Multidimensional Fractionation of Particles
Separations 2023, 10(4), 252; https://doi.org/10.3390/separations10040252 - 13 Apr 2023
Viewed by 693
Abstract
The increasing complexity in particle science and technology requires the ability to deal with multidimensional property distributions. We present the theoretical background for multidimensional fractionations by transferring the concepts known from one dimensional to higher dimensional separations. Particles in fluids are separated by [...] Read more.
The increasing complexity in particle science and technology requires the ability to deal with multidimensional property distributions. We present the theoretical background for multidimensional fractionations by transferring the concepts known from one dimensional to higher dimensional separations. Particles in fluids are separated by acting forces or velocities, which are commonly induces by external fields, e.g., gravitational, centrifugal or electro-magnetic fields. In addition, short-range force fields induced by particle interactions can be employed for fractionation. In this special case, nanoparticle chromatography is a recent example. The framework for handling and characterizing multidimensional separation processes acting on multidimensional particle size distributions is presented. Illustrative examples for technical realizations are given for shape-selective separation in a hydrocyclone and for density-selective separation in a disc separator. Full article
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Article
High-Value Recovery of the Iron via Solvent Extraction from Waste Nickel-Cadmium Battery Sulfuric Acid Leachate Using Saponified D2EHPA
Separations 2023, 10(4), 251; https://doi.org/10.3390/separations10040251 - 12 Apr 2023
Cited by 1 | Viewed by 684
Abstract
A significant amount of iron from the waste nickel-cadmium (Ni-Cd) battery sulfuric acid leachate seriously hinders the separation and recovery of nickel and cadmium. Therefore, an efficient and economical way to remove iron from this leachate is desired. This paper demonstrated the efficient [...] Read more.
A significant amount of iron from the waste nickel-cadmium (Ni-Cd) battery sulfuric acid leachate seriously hinders the separation and recovery of nickel and cadmium. Therefore, an efficient and economical way to remove iron from this leachate is desired. This paper demonstrated the efficient iron extraction from a simulated Ni-Cd battery sulfuric acid leachate with saponified Di (2-ethylhexyl) phosphoric acid (D2EHPA). The iron-loaded D2EHPA was then stripped with oxalic acid and the iron was recovered in the form of iron oxalate. This process realizes the efficient separation and high-value recovery of iron. The results showed that the saponification of the D2EHPA greatly promoted the extraction of iron from the Ni-Cd battery sulfuric acid leachate. Under suitable conditions, the iron’s single-stage extraction rate was more than 95%, and the iron’s single-stage stripping rate was more than 85%. Moreover, the iron’s extraction rate was more than 99% after two theoretical extraction stages, and the stripping rate was 95.6% after two theoretical stripping stages. The slope analysis determines that five molecules of D2EHPA were combined with one molecule of Fe3+ in the extraction process. The FT-IR analysis shows that the extraction mechanism of Fe3+ using the saponified D2EHPA is a cation exchange. These results can help guide the industrial separation and recovery of iron from the waste Ni-Cd battery sulfuric acid leachate. Full article
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Article
Development of the QuEChERS Extraction Method for the Determination of Polychlorinated Biphenyls (Aroclor 1254) in Soil Samples by Using GC-MS
Separations 2023, 10(4), 250; https://doi.org/10.3390/separations10040250 - 12 Apr 2023
Viewed by 728
Abstract
Polychlorinated biphenyls (PCBs) have been found in soil, which has typically been the result of industrial pollution in the past two decades. Although they are banned, PCBs can still be found in soils and other environmental media. For this reason, it is critical [...] Read more.
Polychlorinated biphenyls (PCBs) have been found in soil, which has typically been the result of industrial pollution in the past two decades. Although they are banned, PCBs can still be found in soils and other environmental media. For this reason, it is critical to develop an analytical method that can reliably identify and monitor their sources. This study describes a gas chromatography with mass spectrometry (GC-MS) technique, which was used to detect PCBs in soil samples by using a fast extraction method. Using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, PCBs were more effectively extracted from soil. Different related parameters, such as time of shaking and centrifuging, type of solvent, and clean-up adsorbents, were compared and optimized. As the extraction solvent, acetonitrile/water produced the best results, and as the dispersive solid-phase extraction sorbent, diatomaceous earth produced the best results. Procedures allowed recovery values between 95.3% and 103.2%. A limit of detection of 1.9 µg/kg was determined with relative standard deviations (n = 3) of 2.1–4.0% for intra-day assays and 3.6–5.8% for inter-day assays. It was demonstrated that the method was simple, sensitive, efficient, and environmentally friendly when applied to soil samples. To our knowledge, an integrated approach based on QuEChERS for the determination of Aroclor 1254 in soil has not been published before. It is believed that this approach will eliminate the significant challenge of sample extraction in GC-MS processing, which was considered to be a procedural challenge in previous analyses. Full article
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Article
Magnetically Grafted Carbon Nanotubes Synthesis and Its Oriented Nanochannels Construction in the Poly(Vinylidene Fluoride) (PVDF) Ultrafiltration Membranes
Separations 2023, 10(4), 249; https://doi.org/10.3390/separations10040249 - 11 Apr 2023
Viewed by 607
Abstract
Carbon nanotubes (CNTs) with hollow nanochannels have attracted much attention in preparing high-performance water treatment membranes. In this paper, the grafting polymer chains, including alkynyl terminated poly(methyl methacrylate) methacrylate (PMMA) single chain and PMMA-b-poly (ethylene glycol) methacrylate [P(PEGMA)] diblock molecular chains, were synthesized [...] Read more.
Carbon nanotubes (CNTs) with hollow nanochannels have attracted much attention in preparing high-performance water treatment membranes. In this paper, the grafting polymer chains, including alkynyl terminated poly(methyl methacrylate) methacrylate (PMMA) single chain and PMMA-b-poly (ethylene glycol) methacrylate [P(PEGMA)] diblock molecular chains, were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. A UV-induced click reaction was used to graft different linear polymers onto the surface of magnetic thiol-functionalized carbon nanotubes (mCNTs-SH). The poly(vinylidene fluoride) (PVDF) composite ultrafiltration membrane within the oriented nanochannels was prepared using phase inversion and magnetic field orientation. TEM and XRD results confirmed that the magnetic carbon nanotubes grafted with a diblock molecular chain had good nano-dispersion and orientation array effects in PVDF composite ultrafiltration membrane. The water contact angle of the array mCNT-g-diblock molecular chain-based composite membrane was 48.5°, significantly enhancing the PEGMA chain segments. The composite membrane with CTNs’ nanochannels attained a higher water flux. As the diblock molecular chain grafted mCNTs oriented in the membrane, the water flux reached 17.6 LMH (five times greater than the pure PVDF membrane), while the molecular weight cut-off (MWCO) for PEG1400 rejection could reach higher than 80%. Full article
(This article belongs to the Special Issue Advances in Novel Polymeric Membranes and Membrane Process)
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Article
Box–Behenken-Supported Development and Validation of UPLC Method for the Estimation of Eugenol in Syzygium aromaticum, Cinnamomum tamala, and Myristica fragrance
Separations 2023, 10(4), 248; https://doi.org/10.3390/separations10040248 - 11 Apr 2023
Viewed by 613
Abstract
Eugenol (EUG) is one of the most important components available in several spices, including clove, bay leaves, and nutmeg. These spices are used as flavouring agents in foods and beverages. The aim of the present study is to develop and validate a rapid, [...] Read more.
Eugenol (EUG) is one of the most important components available in several spices, including clove, bay leaves, and nutmeg. These spices are used as flavouring agents in foods and beverages. The aim of the present study is to develop and validate a rapid, simple, sensitive, and robust ultra-performance liquid chromatography (UPLC) technique for the quantitative estimation of EUG in the ultrasound-assisted methanolic extracts of three spices, namely Syzygium aromaticum (L.) Merr. & L.M.Perry (SA), Cinnamomum tamala (Buch.-Ham.) T.Nees & Eberm (CT), and Myristica fragrance Houtt. (MF). EUG was isocratically separated on a UPLC C18 column. The acetonitrile:methanol:water (50:40:10, v/v/v) solvent in different proportions was optimized as the mobile phase for the determination of EUG in ultrasound-assisted methanolic extracts of three different spices. The quantitative estimation of EUG was performed at a 281 nm detection wavelength. The column oven temperature was maintained at 35 ± 5 °C, and the flow rate of the mobile phase was 0.2 mL/min using an injection volume of 1 µL. The UPLC technique was validated according to the ICH guidelines and showed an excellent linearity range of 10–100 ng/mL. The robustness of the method was validated using Box–Behenken response surface design (BBD) software, and a 0.2 mL/min flow rate of the mobile phase, a column oven temperature of 308 K, and a 281 nm detection wavelength were found to be the best optimal conditions for obtaining the highest amount and separation of EUG. The content of EUG in ultrasound-assisted methanolic extracts of SA, CT, and MF using the UPLC technique showed 313.67 ± 0.87 mg g−1, 44.95 ± 0.56 mg g−1, and 59.66 ± 0.41 mg g−1, respectively. The antioxidant potentials of EUG, SA, CT, and MF were analysed using the DPPH (2,2-diphenyl-1-pcrylhydrazil radical) method, which revealed the antioxidant potential of EUG (IC50 = 3.12 µg/mL), standard ascorbic acid (IC50 = 7.06 µg/mL), SA ultrasound-assisted methanolic extract (IC50 = 5.97 µg/mL), CT ultrasound-assisted methanolic extract (IC50 = 49.48 µg/mL), and MF ultrasound-assisted methanolic extract (IC50 = 65.16 µg/mL). The proposed UPLC technique can be used to quantitatively assess various spices, plants, pharmaceutical products, and polyherbal formulations containing EUG as an active constituent. Full article
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Article
A Rapid and Sensitive UPLC-MS/MS Method for Quantifying Capmatinib in Human Liver Microsomes: Evaluation of Metabolic Stability by In Silico and In Vitro Analysis
Separations 2023, 10(4), 247; https://doi.org/10.3390/separations10040247 - 10 Apr 2023
Cited by 1 | Viewed by 616
Abstract
Capmatinib (CMB) is an orally bioavailable mesenchymal–epithelial transition (MET) inhibitor approved by the US-FDA to treat metastatic non-small cell lung cancer (NSCLC) patients, with MET exon 14 skipping mutation. The current study aimed to establish a specific, rapid, and sensitive ultra-performance liquid chromatography [...] Read more.
Capmatinib (CMB) is an orally bioavailable mesenchymal–epithelial transition (MET) inhibitor approved by the US-FDA to treat metastatic non-small cell lung cancer (NSCLC) patients, with MET exon 14 skipping mutation. The current study aimed to establish a specific, rapid, and sensitive ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) analytical method for quantifying CMB in human liver microsomes (HLMs), with therapeutic implications for assessing metabolic stability. Validation of the UPLC-MS/MS analytical method in the HLMs was performed using selectivity, sensitivity, linearity, accuracy, precision, extraction recovery, stability, and matrix effects according to the guidelines for bio-analytical method validation of the US-FDA. CMB was ionized by positive electrospray ionization (ESI) as the ionization source and analysed using multiple reaction monitoring (MRM) as the mass analyser mode. CMB and pemigatinib (PMT) were resolved on the C18 column, with an isocratic mobile phase. The CMB calibration curve showed linearity in the concentration range of 1–3000 ng/mL. The intra- and inter-day accuracy and precision were −7.67–4.48% and 0.46–6.99%, respectively. The lower limit of quantification (LLOQ) of 0.94 ng/mL confirmed the sensitivity of the UPLC-MS/MS analytical method. The intrinsic clearance (Clint) and in vitro half-life (t1/2) of CMB were 61.85 mL/min/kg and 13.11 min, respectively. CMB showed a high extraction ratio. The present study is the first to develop, establish, and standardize UPLC-MS/MS for the purpose of quantifying and evaluating the metabolic stability of CMB. Full article
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Article
Effects of Mechanical Stirring and Ultrasound Treatment on the Separation of Graphite Electrode Materials from Copper Foils of Spent LIBs: A Comparative Study
Separations 2023, 10(4), 246; https://doi.org/10.3390/separations10040246 - 09 Apr 2023
Viewed by 935
Abstract
In this paper, mechanical stirring and ultrasonic treatment are used to separate graphite electrode materials from copper foils in recycling spent lithium-ion batteries (LIBs). Firstly, the effects of ultrasonic power (60–180 W), ultrasonic time (1–8 min), stirring speed (420–2000 rpm), and stirring time [...] Read more.
In this paper, mechanical stirring and ultrasonic treatment are used to separate graphite electrode materials from copper foils in recycling spent lithium-ion batteries (LIBs). Firstly, the effects of ultrasonic power (60–180 W), ultrasonic time (1–8 min), stirring speed (420–2000 rpm), and stirring time (1–8 min) on the abscission rate of active material on copper foil were studied. It was found that the peeling-off ratio of electrode material under ultrasonic treatment was 91.34% compared with stirring treatment (84.22%). The removal of electrode material from copper foil during stirring was mainly through mechanical scrubbing. As a comparison, the generation of the microjets induced by ultrasound, the local high-temperature and high-pressure environment, and the free radicals during ultrasonic treatment are the key factors to further improve electrode material removal efficiency. An integrated ultrasound-mechanical stirrer technique can achieve a high-efficient separation performance (approximately 100% peeling-off ratio) of anode electrode materials from copper foils. The effects of mechanical stirring speed, temperature, and treatment time on the peeling-off ratios of the ultrasound-mechanical stirrer-assisted system were investigated. Finally, the results of XRF (X-ray fluorescence spectrometer), XRD (X-ray diffraction), and SEM-EDS (scanning electron microscopy coupled with energy dispersive X-ray spectroscopy) showed that the as-separated graphite electrode material had high purity and contained almost no copper foil impurities. Numerical simulation analyses briefly showed that the difference between pressure and ultrasonic temperature changes in the boundary between different anode layers (graphite on copper foil in aqueous solution) was the main effective factor in the considerable separation of graphite from copper anode foil under ultrasonic-assisted delamination. Full article
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Article
An Interactive Analysis of Influencing Factors on the Separation Performance of the Screw Press
Separations 2023, 10(4), 245; https://doi.org/10.3390/separations10040245 - 07 Apr 2023
Viewed by 570
Abstract
In order to optimize the separation performance of the screw press and enable its water removal rate and production to meet the production requirements, the influencing rule of the interactive effect of multi-factor parameters on its separation performance was studied by numerical simulation [...] Read more.
In order to optimize the separation performance of the screw press and enable its water removal rate and production to meet the production requirements, the influencing rule of the interactive effect of multi-factor parameters on its separation performance was studied by numerical simulation and experimental means. The internal flow field of the screw press was simulated by Fluent software. The rotation speed of the screw axis, back pressure of the slag outlet, and initial water content were taken as influencing factors, and the water removal rate and production were taken as objective functions. The Box–Behnken method was used to analyze the influencing rules of the interactive factors on the water removal rate and production. The results show that the significant factors affecting the water removal rate of the screw press are in the following order: initial water content > back pressure > rotation speed. The significant factors affecting screw press production are in the following order: rotation speed > back pressure > initial water content. The optimal combination of process parameters for the screw press is an initial water content of 55%, a screw axis rotation speed of 30 r/min, and a 5 kPa back pressure at the slag outlet. The water removal rate of 48.9% and production of 234.2 kg/d were obtained. Full article
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Article
Adsorption of Fatty Acid Methyl Ester Derived from Squid Liver Lipid onto Silica Gel Adsorbent
Separations 2023, 10(4), 244; https://doi.org/10.3390/separations10040244 - 06 Apr 2023
Viewed by 568
Abstract
The purpose of this study is the effective utilization of fisheries waste, squid liver, as a raw material of biodiesel. To obtain biodiesel from squid liver, extracted fatty acids are esterified with methyl alcohol. As the product of the esterification contains many by-products, [...] Read more.
The purpose of this study is the effective utilization of fisheries waste, squid liver, as a raw material of biodiesel. To obtain biodiesel from squid liver, extracted fatty acids are esterified with methyl alcohol. As the product of the esterification contains many by-products, the target product, fatty acid methyl ester of squid liver (SFAME), must be recovered from the products. SFAME is divided into three groups, which are saturated (SF), monounsaturated (MF), and polyunsaturated (PF) fatty acid methyl esters (FAMEs), based on the number of double bonds. In this study, the recovery of SFAME from the product of esterification through adsorption (i.e., dry washing) was investigated. Especially, the effect of solvents, toluene, and methyl alcohol on the recovery efficiency of SFAME using silica gel as an adsorbent was the focus. The competitive adsorption model successfully explained the present adsorption system, and the equilibrium adsorption constants and the saturated adsorption density could be determined by the model analysis. The equilibrium adsorption constant of PF was the largest among the SFAME (PF > MF > SF), and this order could correspond to the values of their dielectric constants. Methanol greatly affected the adsorption behavior of SFAME due to the fact of its hydrophilicity. Full article
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Article
Nanobubble Enhances Rutile Flotation Separation in Styrene Phosphoric Acid System
Separations 2023, 10(4), 243; https://doi.org/10.3390/separations10040243 - 05 Apr 2023
Viewed by 533
Abstract
Due to the weak hydrophobicity of styrene phosphoric acid (SPA), the amount used as a collector for rutile flotation is too large, resulting in high beneficiation costs. In this study, SPA was modified by nanobubbles to enhance its hydrophobicity. In this paper, the [...] Read more.
Due to the weak hydrophobicity of styrene phosphoric acid (SPA), the amount used as a collector for rutile flotation is too large, resulting in high beneficiation costs. In this study, SPA was modified by nanobubbles to enhance its hydrophobicity. In this paper, the modification of SPA by nanobubbles and the adsorption mechanism of SPA on rutile surface before and after modification were studied by means of nanoparticle tracking analysis, micro-bubble flotation test, contact angle test, zeta potential test, etc. The results show that SPA can significantly increase the concentration of bulk nanobubbles, increase the flotation recovery of rutile from 55% to 69%, and reduce the dosage of SPA from 101 mg/L to 70 mg/L. Nanobubbles interact with SPA in the form of water drainage, significantly reducing the zeta potential of the rutile surface and increasing the solid–liquid interface contact angle of rutile surface. A model of the interaction between nanobubbles, SPA, and rutile surface is established, which is helpful to understand the process mechanism of nanobubble flotation. Full article
(This article belongs to the Special Issue Advanced Mineral Resource Separation Technology)
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Article
Quantitation of Ecdysterone and Targeted Analysis of WADA-Prohibited Anabolic Androgen Steroids, Hormones, and Metabolic Modulators in Ecdysterone-Containing Dietary Supplements
Separations 2023, 10(4), 242; https://doi.org/10.3390/separations10040242 - 05 Apr 2023
Viewed by 1098
Abstract
The aim of our research was to perform a comprehensive study of ecdysterone (ECD)-containing dietary supplements (DSs). Two analytical methods were optimised according to the expected concentration of the target compounds: quantitation of ECD by liquid chromatography (LC) coupled to diode array detector [...] Read more.
The aim of our research was to perform a comprehensive study of ecdysterone (ECD)-containing dietary supplements (DSs). Two analytical methods were optimised according to the expected concentration of the target compounds: quantitation of ECD by liquid chromatography (LC) coupled to diode array detector (DAD), and limit test for 47 World Anti-Doping Agency prohibited by LC coupled with tandem mass spectrometer (MS/MS). For quantitation of ECD, the method was fully validated with outstanding performance characteristics (LOD: 35 µg·g−1, LOQ: 115 µg·g−1, CV% < 5%), resulting in significantly lower LOD and shorter runtime than published previously. For limit tests, a chromatographic method was developed to obtain excellent separation, while MS/MS parameters were optimised to allow the lowest possible reporting limit (RL: 0.6–10 ng·g−1 or mL−1). Twenty-one ecdysterone-containing DSs from ten brands were analysed. In all cases, the measured ECD content was much lower than labelled, and 20% of the samples contained a prohibited substance. The concentration of ecdysterone and contaminations varied randomly from batch to batch. The developed methods help to prevent the use of contaminated or useless DSs. Full article
(This article belongs to the Special Issue Application of Hyphenated Techniques in Natural Product Analysis)
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