Special Issue "Advances in Supercritical Fluid Extraction"

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

Deadline for manuscript submissions: 28 February 2021.

Special Issue Editor

Prof. Dr. Yizhak Marcus
Website
Guest Editor
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Interests: The chemistry of liquids and solutions, dealing with inter alia with solvent properties and applications, including those of supercritical fluids, as well as liquid–liquid solvent extraction

Special Issue Information

Dear Colleagues,

The search for neoteric solvents to replace ecologically unfriendly organic solvents, in addition to room temperature ionic liquids and deep eutectic solvents, also includes supercritical solvents. The latter are used as reaction media and for the extraction of valuable substances from a variety of materials. The term ‘supercritical fluid extraction’ is generally applied to the use of supercritical carbon dioxide, neat or with entrainers (co-solvents). However, this term should also include other fluids, namely supercritical water, methanol, or ethanol, among a few others.

The use of supercritical carbon dioxide for the decaffeination of coffee beans is presently a well-established industry, but decaffeination of other beverages is coming to the forefront. Other uses of supercritical carbon dioxide are for extraction processes in the food industry and in the pharmaceutical and cosmetic industries, and these are maturing. On the other hand, supercritical water has found uses in the fuel production industry for extraction of liquid or gaseous fuels from coal or the conversion of plant biomass to biodiesel oil. Supercritical methanol is useful for transesterification processes during such extractions.

It is the purpose of this Special Issue of Process on “Advances in Supercritical Fluid Extraction” to highlight recent progress and to point out trends, prospects, and areas in which further research will be very beneficial for this area.

Prof. Dr. Yizhak Marcus
Guest Editor

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 2000 CHF (Swiss Francs). 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

  • supercritical carbon dioxide
  • supercritical water
  • supercritical methanol
  • supercritical ethanol
  • food industry
  • pharmaceutical industry
  • cosmetic industry
  • fuel processing
  • biomass processing
  • coal

Published Papers (9 papers)

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Research

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Open AccessArticle
Effects of Temperature and Extraction Time on Avocado Flesh (Persea americana) Total Phenolic Yields Using Subcritical Water Extraction
Processes 2021, 9(1), 159; https://doi.org/10.3390/pr9010159 - 15 Jan 2021
Abstract
This paper investigates the optimum extraction temperature for enhanced total phenolic yields extracted from avocado fruit flesh (Persea americana) using subcritical water extraction, as well as the impact of fruit ripeness on phenol extraction efficiency. Additionally, extraction yield against extraction time [...] Read more.
This paper investigates the optimum extraction temperature for enhanced total phenolic yields extracted from avocado fruit flesh (Persea americana) using subcritical water extraction, as well as the impact of fruit ripeness on phenol extraction efficiency. Additionally, extraction yield against extraction time was investigated for time intervals of 10 min over an overall extraction time of 30 min. The subcritical water conditions studied were 18 bar, 87 mL/min, and temperatures of 105 °C, 120 °C, and 140 °C. The total phenolic compounds content was compared for week one avocado flesh and ripe (week four) avocado flesh, with a four-week ripening period between the two samples. The results show that extracting with subcritical water at 105 °C provides the highest phenolic compounds yields of 0.11% and 0.26% by dried mass for week one and ripe fruit (week four), respectively. The experimental results also indicate that the implementation of lower extraction temperatures on week four avocado (i.e., following the selection of week one avocados and allowing them to ripen over a period of one month) enhances the phenolic compounds extraction yields by more than four times relative to the first week’s sample extract, specifically during the first 20 min of extraction. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessArticle
Extraction of Anthocyanins from Red Raspberry for Natural Food Colorants Development: Processes Optimization and In Vitro Bioactivity
Processes 2020, 8(11), 1447; https://doi.org/10.3390/pr8111447 - 11 Nov 2020
Abstract
Heat (HAE)- and ultrasound (UAE)-assisted extraction methods were implemented to recover anthocyanins from red raspberry. Processing time, ethanol concentration, and temperature or ultrasonic power were the independent variables combined in five-level rotatable central composite designs coupled with response surface methodology (RSM) for processes [...] Read more.
Heat (HAE)- and ultrasound (UAE)-assisted extraction methods were implemented to recover anthocyanins from red raspberry. Processing time, ethanol concentration, and temperature or ultrasonic power were the independent variables combined in five-level rotatable central composite designs coupled with response surface methodology (RSM) for processes optimization. The extraction yield and levels of cyanidin-3-O-sophoroside (C3S) and cyanidin-3-O-glucoside (C3G) were monitored by gravimetric and HPLC-DAD-ESI/MSn methods, respectively, and used as response criteria. The constructed theoretical models were successfully fitted to the experimental data and used to determine the optimal extraction conditions. When maximizing all responses simultaneously, HAE originated slightly higher response values (61% extract weight and 8.7 mg anthocyanins/g extract) but needed 76 min processing at 38 °C, with 21% ethanol (v/v), while the UAE process required 16 min sonication at 466 W, using 38% ethanol (v/v). The predictive models were experimentally validated, and the purple-red extracts obtained under optimal condition showed antioxidant activity through lipid peroxidation and oxidative hemolysis inhibition, and antibacterial effects against food-related microorganisms, such as Escherichia coli and Enterococcus faecalis. These results highlight the potential of red raspberry extracts as natural food colorants with bioactive effects and could be exploited by industries interested in the production of anthocyanin-based products. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessArticle
Subcritical Water Extraction of Epigallocatechin Gallate from Camellia sinensis and Optimization Study Using Response Surface Methodology
Processes 2020, 8(9), 1028; https://doi.org/10.3390/pr8091028 - 22 Aug 2020
Cited by 1
Abstract
Background: Camellia sinensis is a plant whose leaves and buds are used to produce tea. With many medicinal activities already found, green tea has been consumed widely in the world. Methods: The subcritical water extraction (SWE) of epigallocatechin gallate (EGCG) from [...] Read more.
Background: Camellia sinensis is a plant whose leaves and buds are used to produce tea. With many medicinal activities already found, green tea has been consumed widely in the world. Methods: The subcritical water extraction (SWE) of epigallocatechin gallate (EGCG) from green tea leaves and the effect of the different extraction conditions are investigated by response surface methodology (RSM). Furthermore, the model of the extraction processes is reviewed for application at the industrial scale. Results: Based on the RSM data, the maximum yield of extraction is determined via optimizing different parameters of the extraction processes. Optimal conditions are as follows: extraction time of 6 min, extraction temperature at 120 °C, and a sample/solvent ratio of 1:40 g/mL. Under such conditions, the best yield of EGCG is 4.665%. Moreover, the model of the extraction processes, which can be utilized for industry scale purpose, indicates a good correlation with the experimental data. Conclusions: Overall, SWE is competent and environmental-friendly, and it is also a highly selective and fast method. SWE is a promising method to take the place of organic solvents used in the extraction of weak polar and even non-polar natural compounds. Further studies on the scale-up of the extraction processes are ongoing. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessArticle
Mathematical Model for the Removal of Essential Oil Constituents during Steam Distillation Extraction
Processes 2020, 8(4), 400; https://doi.org/10.3390/pr8040400 - 29 Mar 2020
Cited by 1
Abstract
Steam distillation is the conventional means by which oils are extracted in the flavour and fragrance industry. A mathematical model for the steam distillation extraction (SDE) of air-dried Ocimum basilicum (basil) leaves has been developed and tested using a small-scale pilot plant. The [...] Read more.
Steam distillation is the conventional means by which oils are extracted in the flavour and fragrance industry. A mathematical model for the steam distillation extraction (SDE) of air-dried Ocimum basilicum (basil) leaves has been developed and tested using a small-scale pilot plant. The model predicts the removal of oil components from the plant matrix and subsequent transfer to the steam. It also accounts for the diffusional transfer of components within the leaf and the simultaneous convective transfer into the vapour phase while also respecting the individual components’ volatilities. It has been applied vertically on an element-by-element basis through the bed for a mixture of major and minor components. The proposed SDE model appears to be a good match between predicted values and the experimental data. The model predicts a faster initial extraction rate for components such as α-pinene and α-terpinene, possibly due to preferential extraction of light, volatile components present in larger quantities. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessArticle
Depigmented Centella asiatica Extraction by Pretreated with Supercritical Carbon Dioxide Fluid for Wound Healing Application
Processes 2020, 8(3), 277; https://doi.org/10.3390/pr8030277 - 28 Feb 2020
Abstract
Centella asiatica has been included in Thai traditional medicinal plants and recipes, as a well-established historical use as a vegetable and tonic. However, when applied in modern formulations, the progressive degradation of the plant pigments occurs, causing color-fading and color variation in the [...] Read more.
Centella asiatica has been included in Thai traditional medicinal plants and recipes, as a well-established historical use as a vegetable and tonic. However, when applied in modern formulations, the progressive degradation of the plant pigments occurs, causing color-fading and color variation in the products. Depigmentation of the comminuted sample using supercritical carbon dioxide (scCO2) fluid extraction with a cosolvent was introduced as a pretreatment to solve the color-fading problem. The contents of compounds with known biological activities and the wound healing activities (antioxidant screening by DPPH and ABTS+ scavenging activities; cell migration assay; matrix metallopeptidase [MMP]-2 inhibition on human skin fibroblast; endothelial cell tube formation assay) of the C. asiatica leaf extracts obtained by conventional ethanolic extraction (CV) and pretreatment using scCO2 extraction, were determined. Total triterpenoids (madecassoside, asiaticoside B, asiaticoside, madecassic acid, terminolic acid and asiatic acid) and total triterpenoid glucosides (madecassoside, asiaticoside B and asiaticoside) were notably more abundant in the extract that had been pretreated using scCO2 than the extract obtained by CV. Moreover, the scCO2 pretreatment not only caused greater relative MMP-2 inhibition (58.48 ± 7.50% of the control), but also exhibited a higher cell migration (59.83 ± 1.85% of the initial) and number of vessels (18.25 ± 4.58) of angiogenesis in the wound healing process. Additionally, positive correlations were observed between the DPPH antioxidant activity and madecassoside content (r = 0.914, p < 0.01), as well as between the cell migration activity and asiaticoside content (r = 0.854, p < 0.05). It can be concluded that the scCO2 pretreatment of C. asiatica can eliminate color pigments from the extract and improve its in vitro wound healing activity. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessArticle
Thermodynamic Analysis of Supercritical Carbon Dioxide Cycle for Internal Combustion Engine Waste Heat Recovery
Processes 2020, 8(2), 216; https://doi.org/10.3390/pr8020216 - 12 Feb 2020
Cited by 2
Abstract
Waste heat recovery of the internal combustion engine (ICE) has attracted much attention, and the supercritical carbon dioxide (S-CO2) cycle was considered as a promising technology. In this paper, a comparison of four S-CO2 cycles for waste heat recovery from [...] Read more.
Waste heat recovery of the internal combustion engine (ICE) has attracted much attention, and the supercritical carbon dioxide (S-CO2) cycle was considered as a promising technology. In this paper, a comparison of four S-CO2 cycles for waste heat recovery from the ICE was presented. Improving the exhaust heat recovery ratio and cycle thermal efficiency were significant to the net output power. A discussion about four different cycles with different design parameters was conducted, along with a thermodynamic performance. The results showed that choosing an appropriate inlet pressure of the compressor could achieve the maximum exhaust heat recovery ratio, and the pressure increased with the rising of the turbine inlet pressure and compressor inlet temperature. The maximum exhaust heat recovery ratio for recuperation and pre-compression of the S-CO2 cycle were achieved at 7.65 Mpa and 5.8 MPa, respectively. For the split-flow recompression cycle, thermal efficiency first increased with the increasing of the split ratio (SR), then decreased with a further increase of the SR, but the exhaust heat recovery ratio showed a sustained downward trend with the increase of the SR. For the split-flow expansion cycle, the optimal SR was 0.43 when the thermal efficiency and exhaust heat recovery ratio achieved the maximum. The highest recovery ratio was 24.75% for the split-flow expansion cycle when the total output power, which is the sum of the ICE power output and turbine mechanical power output, increased 15.3%. The thermal performance of the split-flow expansion cycle was the best compared to the other three cycles. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessArticle
Extraction of Oil and Minor Compounds from Oil Palm Fruit with Supercritical Carbon Dioxide
Processes 2019, 7(2), 107; https://doi.org/10.3390/pr7020107 - 18 Feb 2019
Cited by 5
Abstract
A significant quantity of tocochromanols and carotenoids remains in the residual from palm oil production by traditional screw pressing. Supercritical carbon dioxide extraction was used as alternative method with the purpose to recover better these valuable minor compounds. Total oil yield and co-extracted [...] Read more.
A significant quantity of tocochromanols and carotenoids remains in the residual from palm oil production by traditional screw pressing. Supercritical carbon dioxide extraction was used as alternative method with the purpose to recover better these valuable minor compounds. Total oil yield and co-extracted water were investigated in the course of extraction. Tocochromanols and carotenoids were evaluated, not only in the extraction oil, but also in the oil of residual fibre. Modelling of extraction process was also performed for a further up-scaling. The results showed that oil yield up to 90% could be observed within 120 min. Supercritical carbon dioxide (SCCO2) could extract tocochromanols and carotenoids with concentration in the same range of normal commercial processing palm oil, while co-extracted water remained rather low at a level of 2–4%. Moreover, recovery efficiencies of these minor compounds were much higher in case of extraction processed with supercritical carbon dioxide than those with screw pressing method. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Open AccessArticle
Energy Analysis of the S-CO2 Brayton Cycle with Improved Heat Regeneration
Processes 2019, 7(1), 3; https://doi.org/10.3390/pr7010003 - 20 Dec 2018
Cited by 8
Abstract
Supercritical carbon dioxide (S-CO2) Brayton cycles (BC) are promising alternatives for power generation. Many variants of S-CO2 BC have already been studied to make this technology economically more viable and efficient. In comparison to other BC and Rankine cycles, S-CO [...] Read more.
Supercritical carbon dioxide (S-CO2) Brayton cycles (BC) are promising alternatives for power generation. Many variants of S-CO2 BC have already been studied to make this technology economically more viable and efficient. In comparison to other BC and Rankine cycles, S-CO2 BC is less complex and more compact, which may reduce the overall plant size, maintenance, and the cost of operation and installation. In this paper, we consider one of the configurations of S-CO2 BC called the recompression Brayton cycle with partial cooling (RBC-PC) to which some modifications are suggested with an aim to improve the overall cycle’s thermal efficiency. The type of heat source is not considered in this study; thus, any heat source may be considered that is capable of supplying temperature to the S-CO2 in the range from 500 °C to 850 °C, like solar heaters, or nuclear and gas turbine waste heat. The commercial software Aspen HYSYS V9 (Aspen Technology, Inc., Bedford, MA, USA) is used for simulations. RBC-PC serves as a base cycle in this study; thus, the simulation results for RBC-PC are compared with the already published data in the literature. Energy analysis is done for both layouts and an efficiency comparison is made for a range of turbine operating temperatures (from 500 °C to 850 °C). The heat exchanger effectiveness and its influence on both layouts are also discussed. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)
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Review

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Open AccessFeature PaperReview
Some Advances in Supercritical Fluid Extraction for Fuels, Bio-Materials and Purification
Processes 2019, 7(3), 156; https://doi.org/10.3390/pr7030156 - 13 Mar 2019
Cited by 5
Abstract
Supercritical fluids are used for the extraction of desired ingredients from natural materials, but also for the removal of undesired and harmful ingredients. In this paper, the pertinent physical and chemical properties of supercritical water, methanol, ethanol, carbon dioxide, and their mixtures are [...] Read more.
Supercritical fluids are used for the extraction of desired ingredients from natural materials, but also for the removal of undesired and harmful ingredients. In this paper, the pertinent physical and chemical properties of supercritical water, methanol, ethanol, carbon dioxide, and their mixtures are provided. The methodologies used with supercritical fluid extraction are briefly dealt with. Advances in the application of supercritical extraction to fuels, the gaining of antioxidants and other useful items from biomass, the removal of undesired ingredients or contaminants, and the preparation of nanosized particles of drugs are described. Full article
(This article belongs to the Special Issue Advances in Supercritical Fluid Extraction)

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.

1. Title: Study on supercritical fluid extraction and Bioactivity of essential oil from Baopuxianggui
Author: Dr. Hua Zhang
Abstract: In order to investigate the functional properties of essential oils from Baopuxianggui. This paper studied the extraction of essential oil by supercritical carbon dioxide extraction with dry and crushed Baopuxianggui as raw material. Through single factor analysis, the research discussed the influence of three factors: extraction temperature, extraction pressure and extraction time on the extraction rate of the essential oil. Then the study used the response surface software to optimize the extraction of the process conditions and discussed the antioxidant of it. The best extraction process parameters were: the extraction pressure was 18 MPa, the extraction temperature was 40℃, and the extraction time was 1.6h. Under this condition, the extraction rate of the essential oil was 0.97%. The research evaluated the antioxidant properties of the essential oil through the determination of DPPH., ·OH、ABTS. radical scavenging capacity, and the determination of total reducing power. Based on the results of the four methods, the research concluded that the essential oil has strong antioxidant activity.

 

2. Title: Structure and properties of super-critical water explored by the statistical mechanics theory of molecular liquids

Author: Dr. Hirata

Abstract: Water in the supercritical region in the phase diagram exhibits a markedly different structure and properties from that in the ambient condition, which are useful to control the chemical reactions. Nonetheless, the theoretcial treatment of the matter is not so easy because the region is right next to the critical point. The article is devoted to review the theoretical studies on water in the super-critical region and its properties as a solvent of chemical reaction, carried out by the authors based on the statistical mechanics theory of molecular liquids, or the RISM theory. The manuscript includes the following sections:
(1) Properties of water in a wide range of pressure and temperature
including the super-critical region.
(2) Characterization of super-critical region in terms of the concept of
“Ridge” in the phase diagram.
(3) pKw in the super critical water.
(4) The Diels-Alder reaction in the super-critical water.

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