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Processing of Materials by Supercritical Fluids
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Processing of Materials by Supercritical Fluids

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: closed (15 November 2021) | Viewed by 40403

Special Issue Editor

Dr. Stefano Cardea

E-Mail Website
Guest Editor
Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, Fisciano, SA, Italy
Interests: supercritical-fluids-assisted processes; membranes; aerogels; scaffolds; foams; micro- and nanoparticles
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Supercritical fluids are characterized by unique peculiarities such as solvent power that are comparable to those of liquid organic solvents, and diffusivity comparable to those of gaseous substances, quasi-zero surface tension, and low pollution. As a consequence, several unit operations have been modified and improved through the use of supercritical fluids, with the aim of overcoming their limitations.

Among them, the processes concerning the interaction between materials (inorganic and/or organic) and supercritical fluids are becoming more attractive. Indeed, numerous fields of applications are related to these processes, ranging from the chemical industry to the pharmaceutical industry, from the food industry to tissue engineering, and from mechanical engineering to computer engineering. For example, numerous micronization processes, porous structures generation processes (aerogels, membranes, scaffolds, and foams), fiber- and film-production processes, impregnation processes, etc., have been developed using supercritical fluids.

The aim of this Special Issue is to highlight the processing of material by supercritical fluids. In particular, research works about the interaction between supercritical fluids and organic and/or inorganic materials and the study and development of processes concerning the generation of micro and nanoparticles, fibers, foams, scaffolds, membranes, and aerogels are welcome.

Prof. Dr. Stefano Cardea
Guest Editor

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Keywords

  • Supercritical fluids
  • Materials
  • Aerogels
  • Particles
  • Membranes
  • Fibers
  • Scaffolds

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Related Special Issue

Published Papers (10 papers)

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Research

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13 pages, 1209 KiB  
Article
Influence of Supercritical Carbon Dioxide Extraction Conditions on Extraction Yield and Composition of Nigella sativa L. Seed Oil—Modelling, Optimization and Extraction Kinetics regarding Fatty Acid and Thymoquinone Content
by Grzegorz Gawron, Wojciech Krzyczkowski, Robert Łyżeń, Leszek Kadziński and Bogdan Banecki
Molecules 2021, 26(21), 6419; https://doi.org/10.3390/molecules26216419 - 24 Oct 2021
Cited by 7 | Viewed by 3046
Abstract
Nigella sativa L. is cultivated in many regions and its seeds have found use in variety of foods, but also in traditional medicine due to high content of biologically active essential oils. In this work optimization of supercritical carbon dioxide extraction from N. [...] Read more.
Nigella sativa L. is cultivated in many regions and its seeds have found use in variety of foods, but also in traditional medicine due to high content of biologically active essential oils. In this work optimization of supercritical carbon dioxide extraction from N. sativa seeds was performed using response surface methodology to describe the influence of extraction conditions on oil yield. Kinetics of oil and thymoquinone extraction were analyzed as well. It was demonstrated that in order to collect thymoquinone-rich N. sativa oil fraction, appropriate for health-related applications, the extraction should be carried out at 40 °C and 10–15 MPa. Following application of higher pressure of 35 MPa enables effective extraction of remaining oil rich in polyunsaturated fatty acids suitable for use in food industry. Thymoquinone-dependent antibacterial activity of the N. sativa seed oil was observed against bacterial pathogens: Haemophilus influenzae, Staphylococcus haemolyticus, Staphylococcus epidermidis, Enterococcus faecalis and Escherichia coli. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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18 pages, 3065 KiB  
Article
Chemical Composition, Antioxidant and Cytoprotective Potentials of Carica papaya Leaf Extracts: A Comparison of Supercritical Fluid and Conventional Extraction Methods
by Boon-Keat Khor, Nelson Jeng-Yeou Chear, Juzaili Azizi and Kooi-Yeong Khaw
Molecules 2021, 26(5), 1489; https://doi.org/10.3390/molecules26051489 - 9 Mar 2021
Cited by 23 | Viewed by 6546
Abstract
The leaves of Carica papaya (CP) are rich in natural antioxidants. Carica papaya has traditionally been used to treat various ailments, including skin diseases. This study aims to decipher the antioxidant effects and phytochemical content of different CP leaf extracts (CPEs) obtained using [...] Read more.
The leaves of Carica papaya (CP) are rich in natural antioxidants. Carica papaya has traditionally been used to treat various ailments, including skin diseases. This study aims to decipher the antioxidant effects and phytochemical content of different CP leaf extracts (CPEs) obtained using supercritical carbon dioxide (scCO2) and conventional extraction methods. The antioxidant activities of CPEs were evaluated by cell-free (1,1-diphenyl-2-picryl-hydrazyl (DPPH) and ferric-reduced antioxidative power (FRAP)) and cell-based (H2O2) assay. Both C. papaya leaf scCO2 extract with 5% ethanol (CPSCE) and C. papaya leaf scCO2 extract (CPSC) exhibited stronger DPPH radical scavenging activity than conventional extracts. In the FRAP assay, two hydrophilic extracts (C. papaya leaf ethanol extract (CPEE) and C. papaya freeze-dried leaf juice (CPFD)) showed relatively stronger reducing power compared to lipophilic extracts. Cell-based assays showed that CPFD significantly protected skin fibroblasts from H2O2-induced oxidative stress in both pre-and post-treatment. CPEE protected skin fibroblasts from oxidative stress in a dose-dependent manner while CPSCE significantly triggered the fibroblast recovery after treatment with H2O2. GC-MS analysis indicated that CPSCE had the highest α-tocopherol and squalene contents. By contrast, both CP hydrophilic extracts (CPEE and CPFD) had a higher total phenolic content (TPC) and rutin content than the lipophilic extracts. Overall, CPEs extracted using green and conventional extraction methods showed antioxidative potential in both cell-based and cell-free assays due to their lipophilic and hydrophilic antioxidants, respectively. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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13 pages, 2677 KiB  
Article
Synthesis of Supported Heterogeneous Catalysts by Laser Ablation of Metallic Palladium in Supercritical Carbon Dioxide Medium
by Oleg Parenago, Alexey Rybaltovsky, Evgeniy Epifanov, Andrey Shubnyi, Galina Bragina, Alexey Lazhko, Dmitry Khmelenin, Vladimir Yusupov and Nikita Minaev
Molecules 2020, 25(24), 5807; https://doi.org/10.3390/molecules25245807 - 9 Dec 2020
Cited by 3 | Viewed by 1971
Abstract
To obtain a supported heterogeneous catalyst, laser ablation of metallic palladium in supercritical carbon dioxide was performed in the presence of a carrier, microparticles of γ-alumina. The influence of the ablation process conditions—including supercritical fluid density, ablation, mixing time of the mixture, and [...] Read more.
To obtain a supported heterogeneous catalyst, laser ablation of metallic palladium in supercritical carbon dioxide was performed in the presence of a carrier, microparticles of γ-alumina. The influence of the ablation process conditions—including supercritical fluid density, ablation, mixing time of the mixture, and laser wavelength—on the completeness and efficiency of the deposition of palladium particles on the surface of the carrier was studied. The obtained composites were investigated by scanning and transmission electron microscopy using energy dispersive spectroscopy. We found that palladium particles were nanosized and had a narrow size distribution (2–8 nm). The synthesized composites revealed high activity as catalysts in the liquid-phase hydrogenation of diphenylacetylene. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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10 pages, 831 KiB  
Article
New Design Method for Fabricating Multilayer Membranes Using CO2-Assisted Polymer Compression Process
by Takafumi Aizawa
Molecules 2020, 25(24), 5786; https://doi.org/10.3390/molecules25245786 - 8 Dec 2020
Cited by 3 | Viewed by 1620
Abstract
It was verified that deep learning can be used in creating multilayer membranes with multiple porosities using the CO2-assisted polymer compression (CAPC) method. To perform training while reducing the number of experimental data as much as possible, the experimental data of [...] Read more.
It was verified that deep learning can be used in creating multilayer membranes with multiple porosities using the CO2-assisted polymer compression (CAPC) method. To perform training while reducing the number of experimental data as much as possible, the experimental data of the compression behavior of two layers were expanded to three layers for training, but sufficient accuracy could not be obtained. However, the accuracy was dramatically improved by adding the experimental data of the three layers. The possibility of only simulating process results without the necessity for a model is a merit unique to deep learning. Overall, in this study, the results show that by devising learning data, deep learning is extremely effective in designing multilayer membranes using the CAPC method. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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14 pages, 654 KiB  
Article
Supercritical CO2 Processing of a Functional Beverage Containing Apple Juice and Aqueous Extract of Pfaffia glomerata Roots: Fructooligosaccharides Chemical Stability after Non-Thermal and Thermal Treatments
by Eric Keven Silva, Matheus A. Bargas, Henrique S. Arruda, Renata Vardanega, Glaucia M. Pastore and M. Angela A. Meireles
Molecules 2020, 25(17), 3911; https://doi.org/10.3390/molecules25173911 - 27 Aug 2020
Cited by 15 | Viewed by 2992
Abstract
The effects of supercritical CO2 processing on the chemical stability of fructooligosaccharides (FOS) and other functional and nutritional compounds were evaluated employing non-thermal and thermal approaches. Apple juice was enriched with Pfaffia glomerata roots aqueous extract due to its high content of [...] Read more.
The effects of supercritical CO2 processing on the chemical stability of fructooligosaccharides (FOS) and other functional and nutritional compounds were evaluated employing non-thermal and thermal approaches. Apple juice was enriched with Pfaffia glomerata roots aqueous extract due to its high content of short-chain FOS and then subjected to different levels of temperature (40 and 60 °C), pressure (8 and 21 MPa), and CO2 volume ratio (20 and 50%). The percentage of CO2 volume was evaluated concerning the total volume of the high-pressure reactor. Also, the functional beverage was thermally treated at 105 °C for 10 min. Physicochemical properties (pH and soluble solid content), beta-ecdysone, sugars (glucose, fructose, and sucrose), and FOS (1-kestose, nystose, and fructofuranosylnystose) content were determined. The pH and soluble solid content did not modify after all treatments. The pressure and CO2 volume ratio did not influence the FOS content and their chemical profile, however, the temperature increase from 40 to 60 °C increased the nystose and fructofuranosylnystose content. High-temperature thermal processing favored the hydrolysis of 1-kestose and reduced the sucrose content. Regarding beta-ecdysone, its content remained constant after all stabilization treatments demonstrating thus its high chemical stability. Our results demonstrated that supercritical CO2 technology is a promising technique for the stabilization of FOS-rich beverages since the molecular structures of these fructans were preserved, thus maintaining their prebiotic functionality. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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17 pages, 2023 KiB  
Article
The Influence of Plant Material Enzymatic Hydrolysis and Extraction Conditions on the Polyphenolic Profiles and Antioxidant Activity of Extracts: A Green and Efficient Approach
by Aneta Krakowska-Sieprawska, Katarzyna Rafińska, Justyna Walczak-Skierska and Bogusław Buszewski
Molecules 2020, 25(9), 2074; https://doi.org/10.3390/molecules25092074 - 29 Apr 2020
Cited by 27 | Viewed by 4137
Abstract
The aim of this study was to develop a new comprehensive extraction protocol based on green technology for the enhanced release of polyphenolic compounds from plant cells. In this work, extracts from yerba mate and yellow lupine seed were obtained by using three [...] Read more.
The aim of this study was to develop a new comprehensive extraction protocol based on green technology for the enhanced release of polyphenolic compounds from plant cells. In this work, extracts from yerba mate and yellow lupine seed were obtained by using three different extraction techniques: maceration, supercritical fluid extraction with co-solvent (SFE) and enzyme assisted-supercritical fluid extraction with co-solvent (EA-SFE). Several experimental parameters such as time, type of solvent and co-solvent as well as CO2 flow rate were selected to obtain the highest extraction efficiency. The chemical profiles in the obtained extracts and their biological activity were evaluated. HPLC-MS/MS analysis indicated that the level of phenolic compounds in extracts from yerba mate obtained by EA-SFE was approximately five times higher than for maceration and 3.2 times higher than for SFE. In the case of extracts from yellow lupine seed an approximately 5.6-fold increase was observed in comparison with maceration and SFE with 96% MeOH, and 2.9 times for SFE with 96% EtOH. The developed protocol with a mix of enzymes commonly applied in the agricultural industry significantly raises the efficiency of liberation of secondary metabolites. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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15 pages, 2654 KiB  
Article
Extraction of Galphimines from Galphimia glauca with Supercritical Carbon Dioxide
by Francisco Javier Verónico Sánchez, Octavio Elizalde Solis, Alejandro Zamilpa, Ricardo García Morales, Ma. Dolores Pérez García, Jesús E. Jiménez Ferrer and Jaime Tortoriello
Molecules 2020, 25(3), 477; https://doi.org/10.3390/molecules25030477 - 22 Jan 2020
Cited by 7 | Viewed by 3671
Abstract
The anti-depressive and anxiolytic effect of galphimine B (isolated from Galphimia glauca) has been demonstrated by researchers. Therefore, it is necessary to explore extraction techniques that produce materials with adequate quality for pharmaceutical applications. In this work, supercritical extractions of galphimines from [...] Read more.
The anti-depressive and anxiolytic effect of galphimine B (isolated from Galphimia glauca) has been demonstrated by researchers. Therefore, it is necessary to explore extraction techniques that produce materials with adequate quality for pharmaceutical applications. In this work, supercritical extractions of galphimines from Galphimia glauca were performed in the presence of carbon dioxide. Pressure, temperature, particle diameter, and flow rate effects were examined to explore the conditions with the highest yield and the concentration profile of galphimines in the studied interval. The identification of the nor-seco triterpenoids and galphimine B and E was carried out by HPLC analyses. The mathematical modeling of the extraction curves was attained by the approaches proposed by Sovová and Papamichail et al. According to results, the highest yield 2.22% was obtained at 323.15 K, 326 μm, 3 L/min, and 33.75 MPa. Meanwhile, the content of galphimine B in the extract was, on average, 19.5 mg·g−1. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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Review

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40 pages, 16247 KiB  
Review
Foaming of PLA Composites by Supercritical Fluid-Assisted Processes: A Review
by Jennifer Andrea Villamil Jiménez, Nicolas Le Moigne, Jean-Charles Bénézet, Martial Sauceau, Romain Sescousse and Jacques Fages
Molecules 2020, 25(15), 3408; https://doi.org/10.3390/molecules25153408 - 28 Jul 2020
Cited by 41 | Viewed by 8182
Abstract
Polylactic acid (PLA) is a well-known and commercially available biopolymer that can be produced from different sources. Its different characteristics generated a great deal of interest in various industrial fields. Besides, its use as a polymer matrix for foam production has increased in [...] Read more.
Polylactic acid (PLA) is a well-known and commercially available biopolymer that can be produced from different sources. Its different characteristics generated a great deal of interest in various industrial fields. Besides, its use as a polymer matrix for foam production has increased in recent years. With the rise of technologies that seek to reduce the negative environmental impact of processes, chemical foaming agents are being substituted by physical agents, primarily supercritical fluids (SCFs). Currently, the mass production of low-density PLA foams with a uniform cell morphology using SCFs as blowing agents is a challenge. This is mainly due to the low melt strength of PLA and its slow crystallization kinetics. Among the different options to improve the PLA characteristics, compounding it with different types of fillers has great potential. This strategy does not only have foaming advantages, but can also improve the performances of the final composites, regardless of the implemented foaming process, i.e., batch, injection molding, and extrusion. In addition, the operating conditions and the characteristics of the fillers, such as their size, shape factor, and surface chemistry, play an important role in the final foam morphology. This article proposes a critical review on the different SCF-assisted processes and effects of operating conditions and fillers on foaming of PLA composites. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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32 pages, 1818 KiB  
Review
Supercritical Fluid Applications in the Design of Novel Antimicrobial Materials
by Irena Zizovic
Molecules 2020, 25(11), 2491; https://doi.org/10.3390/molecules25112491 - 27 May 2020
Cited by 15 | Viewed by 4524
Abstract
Bacterial resistance to antibiotics is one of the biggest problems in the modern world. The prevention of bacterial spreading from hospitals to the community and vice versa is an issue we have to deal with. This review presents a vast potential of contemporary [...] Read more.
Bacterial resistance to antibiotics is one of the biggest problems in the modern world. The prevention of bacterial spreading from hospitals to the community and vice versa is an issue we have to deal with. This review presents a vast potential of contemporary high-pressure techniques in the design of materials with antimicrobial activity. Scientists from all over the world came up with ideas on how to exploit extraordinary properties of supercritical fluids in the production of advantageous materials in an environmentally friendly way. The review summarizes reported methods and results. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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Other

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10 pages, 616 KiB  
Brief Report
Preliminary Evaluation of Supercritical Carbon Dioxide Extracted Dabai Pulp Oleoresin as a New Alternative Fat
by Noor Atiqah Aizan Abdul Kadir, Azrina Azlan, Faridah Abas and Intan Safinar Ismail
Molecules 2021, 26(18), 5545; https://doi.org/10.3390/molecules26185545 - 13 Sep 2021
Cited by 3 | Viewed by 2541
Abstract
There has been growing interest among food scientists in producing a toxin-free fat as an end product with varying physical or nutritional properties of interest to the food industry. Oleoresin is a rich source of bioactive compounds which consumers can easily add to [...] Read more.
There has been growing interest among food scientists in producing a toxin-free fat as an end product with varying physical or nutritional properties of interest to the food industry. Oleoresin is a rich source of bioactive compounds which consumers can easily add to a large variety of food. Dabai (Canarium odontophyllum) pulp oleoresin (DPL) was extracted using supercritical carbon dioxide (SC-CO2) extraction, a green extraction technology. This study investigates the quality of SC-CO2 extracted DPL in discovering its potential as a new alternative fat. The extraction experiment was carried out at a pressure of 40 MPa and a temperature of 40 °C. DPL is a saturated fatty acid (SFA)-rich fat due to its high SFA composition (47.72 ± 0.01%). In addition, the low content of peroxide value (PV) (5.60 ± 0.09 mEq/kg) and free fatty acids (FFA) (3.40 ± 0.03%) indicate the quality and stability of DPL for various applications besides food consumption. DPL also has a low slip melting point (SMP) (20.20 ± 0.03 °C), and HPLC-FID revealed that DPL contained 0.13 ± 0.02 mg/100 g of vitamin E (α-tocopherol), indicating its potential application as a solid fat with a bioactive compound. This present work demonstrates the possible prospect of DPL in the formulation of end products for food industries. Full article
(This article belongs to the Special Issue Processing of Materials by Supercritical Fluids)
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