molecules-logo

Journal Browser

Journal Browser

Applications of Supercritical Carbon Dioxide

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

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 26297

Special Issue Editors

Department of Applied Science and Technology, Politecnico di Torino, corso Duca degli Abruzzi, 24, 10129 Torino, Italy
Interests: solubility of drugs in supercritical fluids; supercritical techniques for the preparation of drug delivery systems; supercritical drying and aerogels; supercritical-CO2-mediated inclusion complexation of cyclodextrins; drug delivery
Special Issues, Collections and Topics in MDPI journals
Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Turin, Italy
Interests: nanoporous materials; surface chemistry of materials; nanostructured materials for drug delivery; drug adsorption by means of supercritical carbon dioxide; nanoporous materials in adsorption and purification processes; nanostructured materials in heterogeneous catalysis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Supercritical carbon dioxide is a green, economic, non-flammable, and recyclable medium that could replace organic solvents in many industrial processes. Its solvent power towards many organic molecules can be easily tuned by simply varying temperature and/or pressure or by adding small amounts of cosolvents. On the other hand, a simple depressurization step allows for solvent-free products to be obtained. Furthermore, the gas-like viscosity and diffusivity allow for deep penetration of this fluid in different solid matrices, which may also be accompanied by swelling and plasticization.

These outstanding properties have given rise to many extraction applications, such as the recovery of triglycerides, natural colorants, aromas, polyphenols, and other nutraceuticals from different vegetable sources or food wastes, which could interest the cosmetic, food, or pharmaceutical industry. Supercritical carbon dioxide can also be used as an impregnating medium to achieve, for example, the water-free dyeing of textiles or the incorporation of drugs into different supports (biocompatible polymers, cyclodextrins, inorganic porous matrices, etc) to obtain solvent-free drug delivery systems or other biomedical devices. The solvent or antisolvent power of this fluid can also be exploited to set up many micronization techniques for the generation of fine particles or nanomaterials, while its low surface tension allows for the supercritical drying of aerogels to be performed. Other applications include the purification and sterilization of foods and polymers as well as the search for new chemical production processes, where carbon dioxide can be a suitable environment to conduct innovative catalytic and biocatalytic reactions.

The aim of this Special Issue is to provide an overview of the huge amount of processes that can exploit the properties of supercritical carbon dioxide. Contributions, in the form of research or review articles, that cover innovative aspects of the use of this fluid in extraction, impregnation, drying, micronization, sterilization, and chemical processes will be welcome.

Prof. Mauro Banchero
Prof. Dr. Barbara Onida
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 submissions that pass pre-check are 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. Molecules is an international peer-reviewed open access semimonthly 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 2700 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;
  • solubility;
  • extraction;
  • impregnation;
  • sterilization;
  • micronization;
  • aerogels;
  • reactions in supercritical carbon dioxide.

Published Papers (10 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

14 pages, 3271 KiB  
Article
Piroxicam Loading onto Mesoporous Silicas by Supercritical CO2 Impregnation
by Marta Gallo, Luca Serpella, Federica Leone, Luigi Manna, Mauro Banchero, Silvia Ronchetti and Barbara Onida
Molecules 2021, 26(9), 2500; https://doi.org/10.3390/molecules26092500 - 25 Apr 2021
Cited by 5 | Viewed by 2125
Abstract
Piroxicam (PRX) is a commonly prescribed nonsteroidal anti-inflammatory drug. Its efficacy, however, is partially limited by its low water solubility. In recent years, different studies have tackled this problem and have suggested delivering PRX through solid dispersions. All these strategies, however, involve the [...] Read more.
Piroxicam (PRX) is a commonly prescribed nonsteroidal anti-inflammatory drug. Its efficacy, however, is partially limited by its low water solubility. In recent years, different studies have tackled this problem and have suggested delivering PRX through solid dispersions. All these strategies, however, involve the use of potentially harmful solvents for the loading procedure. Since piroxicam is soluble in supercritical CO2 (scCO2), the present study aims, for the first time, to adsorb PRX onto mesoporous silica using scCO2, which is known to be a safer and greener technique compared to the organic solvent-based ones. For comparison, PRX is also loaded by adsorption from solution and incipient wetness impregnation using ethanol as solvent. Two different commercial mesoporous silicas are used (SBA-15 and Grace Syloid® XDP), which differ in porosity order and surface silanol population. Physico-chemical analyses show that the most promising results are obtained through scCO2, which yields the amorphization of PRX, whereas some crystallization occurs in the case of adsorption from solution and IWI. The highest loading of PRX by scCO2 is obtained in SBA-15 (15 wt.%), where molecule distribution appears homogeneous, with very limited pore blocking. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

19 pages, 9582 KiB  
Article
Solubility of Anthraquinone Derivatives in Supercritical Carbon Dioxide: New Correlations
by Ratna Surya Alwi, Chandrasekhar Garlapati and Kazuhiro Tamura
Molecules 2021, 26(2), 460; https://doi.org/10.3390/molecules26020460 - 17 Jan 2021
Cited by 15 | Viewed by 2571
Abstract
Solubility of several anthraquinone derivatives in supercritical carbon dioxide was readily available in the literature, but correcting ability of the existing models was poor. Therefore, in this work, two new models have been developed for better correlation based on solid–liquid phase equilibria. The [...] Read more.
Solubility of several anthraquinone derivatives in supercritical carbon dioxide was readily available in the literature, but correcting ability of the existing models was poor. Therefore, in this work, two new models have been developed for better correlation based on solid–liquid phase equilibria. The new model has five adjustable parameters correlating the solubility isotherms as a function of temperature. The accuracy of the proposed models was evaluated by correlating 25 binary systems. The proposed models observed provide the best overall correlations. The overall deviation between the experimental and the correlated results was less than 11.46% in averaged absolute relative deviation (AARD). Moreover, exiting solubility models were also evaluated for all the compounds for the comparison purpose. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

14 pages, 2967 KiB  
Article
Optical Diagnostics of Supercritical CO2 and CO2-Ethanol Mixture in the Widom Delta
by Evgenii Mareev, Timur Semenov, Alexander Lazarev, Nikita Minaev, Alexander Sviridov, Fedor Potemkin and Vyacheslav Gordienko
Molecules 2020, 25(22), 5424; https://doi.org/10.3390/molecules25225424 - 19 Nov 2020
Cited by 13 | Viewed by 2261
Abstract
The supercritical CO2 (scCO2) is widely used as solvent and transport media in different technologies. The technological aspects of scCO2 fluid applications strongly depend on spatial–temporal fluctuations of its thermodynamic parameters. The region of these parameters’ maximal fluctuations on [...] Read more.
The supercritical CO2 (scCO2) is widely used as solvent and transport media in different technologies. The technological aspects of scCO2 fluid applications strongly depend on spatial–temporal fluctuations of its thermodynamic parameters. The region of these parameters’ maximal fluctuations on the p-T (pressure-temperature) diagram is called Widom delta. It has significant practical and fundamental interest. We offer an approach that combines optical measurements and molecular dynamics simulation in a wide range of pressures and temperatures. We studied the microstructure of supercritical CO2 fluid and its binary mixture with ethanol in a wide range of temperatures and pressures using molecular dynamics (MD) simulation. MD is used to retrieve a set of optical characteristics such as Raman spectra, refractive indexes and molecular refraction and was verified by appropriate experimental measurements. We demonstrated that in the Widom delta the monotonic dependence of the optical properties on the CO2 density is violated. It is caused by the rapid increase of density fluctuations and medium-sized (20–30 molecules) cluster formation. We identified the correlation between cluster parameters and optical properties of the media; in particular, it is established that the clusters in the Widom delta acts as a seed for clustering in molecular jets. MD demonstrates that the cluster formation is stronger in the supercritical CO2-ethanol mixture, where the extended binary clusters are formed; that is, the nonlinear refractive index significantly increased. The influence of the supercritical state in the cell on the formation of supersonic cluster jets is studied using the Mie scattering technique. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

12 pages, 2487 KiB  
Article
Diffusion of Quinine with Ethanol as a Co-Solvent in Supercritical CO2
by Yury Gaponenko, Aliaksandr Mialdun and Valentina Shevtsova
Molecules 2020, 25(22), 5372; https://doi.org/10.3390/molecules25225372 - 17 Nov 2020
Cited by 4 | Viewed by 1882
Abstract
This study aims at contributing to quinine extraction using supercritical CO2 and ethanol as a co-solvent. The diffusion coefficients of quinine in supercritical CO2 are measured using the Taylor dispersion technique when quinine is pre-dissolved in ethanol. First, the diffusion coefficients [...] Read more.
This study aims at contributing to quinine extraction using supercritical CO2 and ethanol as a co-solvent. The diffusion coefficients of quinine in supercritical CO2 are measured using the Taylor dispersion technique when quinine is pre-dissolved in ethanol. First, the diffusion coefficients of pure ethanol in the supercritical state of CO2 were investigated in order to get a basis for seeing a relative change in the diffusion coefficient with the addition of quinine. We report measurements of the diffusion coefficients of ethanol in scCO2 in the temperature range from 304.3 to 343 K and pressures of 9.5, 10 and 12 MPa. Next, the diffusion coefficients of different amounts of quinine dissolved in ethanol and injected into supercritical CO2 were measured in the same range of temperatures at p = 12 Mpa. At the pressure p = 9.5 MPa, which is close to the critical pressure, the diffusion coefficients were measured at the temperature, T = 343 K, far from the critical value. It was found that the diffusion coefficients are significantly dependent on the amount of quinine in a small range of its content, less than 0.1%. It is quite likely that this behavior is associated with a change in the spatial structure, that is, the formation of clusters or compounds, and a subsequent increase in the molecular weight of the diffusive substance. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

13 pages, 1374 KiB  
Article
Dewatering Green Sapwood Using Carbon Dioxide Undergoing Cyclical Phase Change between Supercritical Fluid and Gas
by Robert A. Franich, Roger Meder and Volker C. Behr
Molecules 2020, 25(22), 5367; https://doi.org/10.3390/molecules25225367 - 17 Nov 2020
Cited by 7 | Viewed by 1796
Abstract
Conventional kiln drying of wood operates by the evaporation of water at elevated temperature. In the initial stage of drying, mobile water in the wood cell lumen evaporates. More slowly, water bound in the wood cell walls evaporates, requiring the breaking of hydrogen [...] Read more.
Conventional kiln drying of wood operates by the evaporation of water at elevated temperature. In the initial stage of drying, mobile water in the wood cell lumen evaporates. More slowly, water bound in the wood cell walls evaporates, requiring the breaking of hydrogen bonds between water molecules and cellulose and hemicellulose polymers in the cell wall. An alternative for wood kiln drying is a patented process for green wood dewatering through the molecular interaction of supercritical carbon dioxide with water of wood cell sap. When the system pressure is reduced to below the critical point, phase change from supercritical fluid to gas occurs with a consequent large change in CO2 volume. This results in the efficient, rapid, mechanical expulsion of liquid sap from wood. The end-point of this cyclical phase-change process is wood dewatered to the cell wall fibre saturation point. This paper describes dewatering over a range of green wood specimen sizes, from laboratory physical chemistry studies to pilot-plant trials. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were applied to study the fundamental mechanisms of the process, which were contrasted with similar studies of conventional thermal wood drying. In conclusion, opportunities and impediments towards the commercialisation of the green wood dewatering process are discussed. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

21 pages, 2340 KiB  
Article
Supercritical Extraction of Red Propolis: Operational Conditions and Chemical Characterization
by João Henrique de Oliveira Reis, Bruna Aparecida Souza Machado, Gabriele de Abreu Barreto, Jeancarlo Pereira dos Anjos, Larissa Moraes dos Santos Fonseca, Alex Alisson Bandeira Santos, Fernando Luiz Pellegrini Pessoa and Janice Izabel Druzian
Molecules 2020, 25(20), 4816; https://doi.org/10.3390/molecules25204816 - 20 Oct 2020
Cited by 8 | Viewed by 2657
Abstract
The objective of this study was to determine the best operational conditions for obtaining red propolis extract with high antioxidant potential through supercritical fluid extraction (SFE) technology, using carbon dioxide (CO2) as the supercritical fluid and ethanol as the cosolvent. The [...] Read more.
The objective of this study was to determine the best operational conditions for obtaining red propolis extract with high antioxidant potential through supercritical fluid extraction (SFE) technology, using carbon dioxide (CO2) as the supercritical fluid and ethanol as the cosolvent. The following parameters were studied: overall extraction curve, S/F (mass of CO2/mass of sample), cosolvent percentage (0, 1, 2 and 4%) and global yield isotherms as a function of different pressures (250, 350 and 450 bar) and temperatures (31.7, 40 and 50 °C). Within the investigated parameters, the best conditions found were an S/F of 131 and the use of ethanol at the highest concentration (4% w/w), which resulted in higher extract yields and higher content of antioxidant compounds. Formononetin, the main biomarker of red propolis, was the compound found at the highest amounts in the extracts. As expected, the temperature and pressure conditions also influenced the process yield, with 350 bar and 40 °C being the best conditions for obtaining bioactive compounds from a sample of red propolis. The novel results for red propolis found in this study show that it is possible to obtain extracts with high antioxidant potential using a clean technology under the defined conditions. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Graphical abstract

18 pages, 3210 KiB  
Article
Application of Supercritical Solvent Impregnation for Production of Zeolite Modified Starch-Chitosan Polymers with Antibacterial Properties
by Jelena Pajnik, Ivana Lukić, Jelena Dikić, Jelena Asanin, Milan Gordic, Dusan Misic, Irena Zizović and Malgorzata Korzeniowska
Molecules 2020, 25(20), 4717; https://doi.org/10.3390/molecules25204717 - 15 Oct 2020
Cited by 19 | Viewed by 2835
Abstract
In the present study, supercritical solvent impregnation (SSI) has been applied to incorporate thymol into bio-composite polymers as a potential active packaging material. Thymol, a natural component with a proven antimicrobial activity, was successfully impregnated into starch-chitosan (SC) and starch-chitosan-zeolite (SCZ) films using [...] Read more.
In the present study, supercritical solvent impregnation (SSI) has been applied to incorporate thymol into bio-composite polymers as a potential active packaging material. Thymol, a natural component with a proven antimicrobial activity, was successfully impregnated into starch-chitosan (SC) and starch-chitosan-zeolite (SCZ) films using supercritical carbon dioxide (scCO2) as a solvent. Experiments were performed at 35 °C, pressures of 15.5 and 30 MPa, and an impregnation time in the range of 4–24 h. The highest impregnation yields of SC films with starch to chitosan mass ratios of 1:1 and 1:2 were 10.80% and 6.48%, respectively. The addition of natural zeolite (15–60%) significantly increased the loading capacity of films enabling thymol incorporation in a quantity of 16.7–27.3%. FTIR and SEM analyses were applied for the characterization of the films. Mechanical properties and water vapor permeability of films before and after the impregnation were tested as well. Thymol release kinetics in deionized water was followed and modeled by the Korsmeyer-Peppas and Weibull model. SCZ films with thymol loading of approximately 24% exhibited strong antibacterial activity against E. coli and methicillin-resistant Staphylococcus (S.) aureus (MRSA). Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

11 pages, 3384 KiB  
Article
Study of Dispersions of Carbon Nanotubes Modified by the Method of Rapid Expansion of Supercritical Suspensions
by Konstantin B. Ustinovich, Victor V. Ivanov, Yurij M. Tokunov, Alexander A. Loshkarev, Natalya I. Sapronova, Anton M. Vorobei, Olga O. Parenago and Michael G. Kiselev
Molecules 2020, 25(18), 4061; https://doi.org/10.3390/molecules25184061 - 05 Sep 2020
Cited by 9 | Viewed by 2798
Abstract
The effectiveness of carbon nanotubes (CNT) deagglomeration by rapid expansion of supercritical suspensions (RESS) in nitrogen and carbon dioxide fluids was studied in this work. Two different mechanisms of deagglomeration were proposed for these two fluids at various temperature and pressure conditions. Ultrasound [...] Read more.
The effectiveness of carbon nanotubes (CNT) deagglomeration by rapid expansion of supercritical suspensions (RESS) in nitrogen and carbon dioxide fluids was studied in this work. Two different mechanisms of deagglomeration were proposed for these two fluids at various temperature and pressure conditions. Ultrasound attenuation spectroscopy was applied as an express method of determining median diameter and aspect ratio of CNTs. At least twofold reduction of the diameter was shown for CNT bundles processed by RESS technique. Aspect ratio of processed CNTs, calculated from acoustic attenuation spectra, increased to 340. These results were in a good agreement with atomic force microscopy data. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

21 pages, 8684 KiB  
Article
Evaluation of Supercritical CO2-Assisted Protocols in a Model of Ovine Aortic Root Decellularization
by Elvira R. Gafarova, Ekaterina A. Grebenik, Alexey E. Lazhko, Anastasia A. Frolova, Anastasia S. Kuryanova, Alexandr V. Kurkov, Ilya A. Bazhanov, Byron S. Kapomba, Nastasia V. Kosheleva, Ivan A. Novikov, Anatoly B. Shekhter, Elena N. Golubeva, Anna B. Soloviova and Peter S. Timashev
Molecules 2020, 25(17), 3923; https://doi.org/10.3390/molecules25173923 - 27 Aug 2020
Cited by 10 | Viewed by 2860
Abstract
One of the leading trends in the modern tissue engineering is the development of new effective methods of decellularization aimed at the removal of cellular components from a donor tissue, reducing its immunogenicity and the risk of rejection. Supercritical CO2 (scCO2 [...] Read more.
One of the leading trends in the modern tissue engineering is the development of new effective methods of decellularization aimed at the removal of cellular components from a donor tissue, reducing its immunogenicity and the risk of rejection. Supercritical CO2 (scCO2)-assisted processing has been proposed to improve the outcome of decellularization, reduce contamination and time costs. The resulting products can serve as personalized tools for tissue-engineering therapy of various somatic pathologies. However, the decellularization of heterogeneous 3D structures, such as the aortic root, requires optimization of the parameters, including preconditioning medium composition, the type of co-solvent, values of pressure and temperature inside the scCO2 reactor, etc. In our work, using an ovine aortic root model, we performed a comparative analysis of the effectiveness of decellularization approaches based on various combinations of these parameters. The protocols were based on the combinations of treatments in alkaline, ethanol or detergent solutions with scCO2-assisted processing at different modes. Histological analysis demonstrated favorable effects of the preconditioning in a detergent solution. Following processing in scCO2 medium provided a high decellularization degree, reduced cytotoxicity, and increased ultimate tensile strength and Young’s modulus of the aortic valve leaflets, while the integrity of the extracellular matrix was preserved. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Graphical abstract

Review

Jump to: Research

20 pages, 1803 KiB  
Review
Supercritical Carbon Dioxide-Based Processes in Photocatalytic Applications
by Paola Franco, Olga Sacco, Vincenzo Vaiano and Iolanda De Marco
Molecules 2021, 26(9), 2640; https://doi.org/10.3390/molecules26092640 - 30 Apr 2021
Cited by 5 | Viewed by 2313
Abstract
Conventional methods generally used to synthesize heterogeneous photocatalysts have some drawbacks, mainly the difficult control/preservation of catalysts’ morphology, size or structure, which strongly affect the photocatalytic activity. Supercritical carbon dioxide (scCO2)-assisted techniques have recently been shown to be a promising approach [...] Read more.
Conventional methods generally used to synthesize heterogeneous photocatalysts have some drawbacks, mainly the difficult control/preservation of catalysts’ morphology, size or structure, which strongly affect the photocatalytic activity. Supercritical carbon dioxide (scCO2)-assisted techniques have recently been shown to be a promising approach to overcome these limitations, which are still a challenge. In addition, compared to traditional methods, these innovative techniques permit the synthesis of high-performance photocatalysts by reducing the use of toxic and polluting solvents and, consequently, the environmental impact of long-term catalyst preparation. Specifically, the versatility of scCO2 allows to prepare catalysts with different structures (e.g., nanoparticles or metal-loaded supports) by several supercritical processes for the photocatalytic degradation of various compounds. This is the first updated review on the use of scCO2-assisted techniques for photocatalytic applications. We hope this review provides useful information on different approaches and future perspectives. Full article
(This article belongs to the Special Issue Applications of Supercritical Carbon Dioxide)
Show Figures

Figure 1

Back to TopTop