Supercritical Fluid Research Articles

Stabilizing effects of higher-order quantum corrections on charged BTZ black hole thermodynamics

In this paper, we study the thermodynamic properties and stability of static charged BTZ black holes with the inclusion of higher-order quantum corrections. The corrections to the entropy, mass, and Helmholtz free energy are derived, revealing the intricate interplay between quantum effects and classical gravitational forces in the context of black hole thermodynamics. The study of the specific heat capacity shows that higher-order corrections stabilize the system by removing the instabilities present at lower orders. The analysis of the van der Waals-like isotherms demonstrates the continuous transition from a highly compressible to an almost incompressible regime as the volume is decreased, akin to the behavior of supercritical fluids. Notably, the isotherms do not exhibit any regions of negative compressibility, indicating the absence of instabilities. Furthermore, the convexity of the Helmholtz free energy as a function of volume confirms the stability of the charged BTZ black hole system. These findings provide valuable insights into the complex thermodynamic landscape of three-dimensional black holes and the role of quantum corrections in shaping their behavior.

Recent advancements toward the incremsent of drug solubility using environmentally-friendly supercritical CO2: a machine learning perspective.

Inadequate bioavailability of therapeutic drugs, which is often the consequence of their unacceptable solubility and dissolution rates, is an indisputable operational challenge of pharmaceutical companies due to its detrimental effect on the therapeutic efficacy. Over the recent decades, application of supercritical fluids (SCFs) (mainly SCCO2) has attracted the attentions of many scientists as promising alternative of toxic and environmentally-hazardous organic solvents due to possessing positive advantages like low flammability, availability, high performance, eco-friendliness and safety/simplicity of operation. Nowadays, application of different machine learning (ML) as a versatile, robust and accurate approach for the prediction of different momentous parameters like solubility and bioavailability has been of great attentions due to the non-affordability and time-wasting nature of experimental investigations. The prominent goal of this article is to review the role of different ML-based tools for the prediction of solubility/bioavailability of drugs using SCCO2. Moreover, the importance of solubility factor in the pharmaceutical industry and different possible techniques for increasing the amount of this parameter in poorly-soluble drugs are comprehensively discussed. At the end, the efficiency of SCCO2 for improving the manufacturing process of drug nanocrystals is aimed to be discussed.

Advances and challenges in the fractionation of edible oils and fats through supercritical fluid processing.

Petrochemical solvents are widely used for the extraction and fractionation of biomolecules from edible oils and fats at an industrial scale. However, owing to its safety concerns, toxicity, price fluctuations, and sustainability, alternative solvents and technologies have been actively explored in recent years. Technologies, such as ultrasound and microwave-assisted extraction, supercritical carbon dioxide extraction, supercritical fluid fractionation, and sub-critical water extraction, and solvents, like ionic liquids and deep eutectic solvents, are reported for extraction and fractionation of biomolecules. Among them, supercritical carbon dioxide extraction and fractionation are some of the most promising green technologies with the potential to replace petrochemical-based conventional techniques. The addition of cosolvents, such as water, ethanol, and acetone, improves the extraction of amphiphilic and polar compounds from edible oils and fats. Supercritical fluid processing has diverse applications, including concentration of solutes, selective separation of desired molecules, and separation of undesirable compounds from the feed material. Temperature, pressure, particle size, porosity, flow rate, solvent-to-feed ratio, density, viscosity, diffusivity, solubility, partition coefficient, and separation factor are the fundamental factors governing the extraction and fractionation of desired biomolecules from lipids. Supercritical fluids stand alone compared to conventional fluids, because of their tunable solvent properties. Overall, it is to be noted that supercritical fluid-based methods have lots of scope to replace conventional solvent-based methods and progress toward the creation of sustainable food-processing techniques. This review critically evaluates the parameters responsible for the extraction and fractionation of biomolecules from edible oils and fats under supercritical conditions.

Tracing the Oxidizing State and Element‐Mobilizing Fluids in Continental Subduction Zones: Insights From the Granitic Melt‐Eclogite Interface

AbstractFluids in subduction zones significantly influence element mobility, isotope fractionation, and mass transfer. However, unraveling the source, composition, and redox state of fluids in continental subduction zones poses a significant challenge. This study focuses on a granitic melt‐eclogite contact interface, along with adjacent granite and eclogite from the Sulu ultrahigh‐pressure metamorphic belt in East China. The interface exhibits complex mineral assemblages, enriched rare earth elements (REEs), and high field strength elements (HFSEs). Zircon grains from the interface show an age of ∼217 ± 9 Ma, slightly later than peak metamorphism, along with the presence of coesite inclusions. These findings suggest that the interfacial fluid likely formed from the mixing of granitic anatectic melt and aqueous fluid from the eclogite during the initial exhumation of the Sulu terrane. The interaction resulted in the eclogite acquiring substantial REEs and HFSEs, suggesting the interfacial fluid's effective element‐transporting capability and potential supercritical fluid properties. Zircon Ce anomaly and Fe3+/Fe2+ oxybarometer data indicate a highly oxidizing interfacial fluid, analogous to arc magmas in oxygen fugacity. This led to the preferential loss of isotopically heavier Cr from the eclogite during fluid‐eclogite interaction, evidenced by heavier Cr isotopic compositions in the interface (δ53Cr = −0.04 to −0.05‰) compared to adjacent eclogite (δ53Cr as low as −0.11‰). In summary, our results highlight the presence of strong oxidizing and element‐mobilizing fluids in continental subduction zones, offering insights into supercritical fluid recognition and the genesis of oxidizing arc magmas in subduction zones.

On the Potential of Manufacturing Multi-Material Components With Micro/Nanocellular Structures Via the Hybrid Process of Electromagnetic Forming Injection Foaming

Abstract Multimaterial design with a combination of solid and foam structures offers a promising avenue for reducing component weight while enhancing their functionalities. However, the complexity of multistage manufacturing processes poses significant challenges to adopting such approaches. To address these challenges, this paper introduces an innovative concept known as Electromagnetic Forming Injection Foaming (EFIF), which integrates injection molding, forming, and foaming processes into a single hybrid process. This process begins with a simultaneous filling-forming phase, followed by supercritical fluid (SCF) assisted foaming controlled by electromagnetic forming. Through a series of experimental and analytical studies, this work investigates the feasibility and effectiveness of EFIF. First, the impact of pressure drop rate and pressure drop on cell size and density is examined through a specialized experimental setup enabling performing injection, forming, and foaming processes in a single operation. The potential influence of electromagnetic forming on foam injection molding is explored through experiments focusing on the effects of a polymer layer between sheet metal blank and the electromagnetic coils. Additionally, an analytical study evaluates the EFIF process by calculating expected pressure drop rates under different processing conditions and their influence on cell nucleation rates. The results showed the possibility of achieving pressure drop rates up to 1.5 × 105 bar/sec, resulting in nucleation rates up to 1.77 × 109 nuclei/cm3sec. Overall, this paper highlights the potential of EFIF to merge existing technologies into a scalable solution for manufacturing multimaterial components with micro- to nanocellular polymer foams.

Upstream heating history effects on heat transfer of supercritical R134a in transcritical organic Rankine cycle

A comprehensive understanding on the heat transfer of supercritical working fluid is critical for the design of vapor generator in transcritical Organic Rankine Cycles. The thermal entrance region under supercritical pressure conditions is relatively complex and remains unresolved. To this end, this study investigates heat transfer to supercritical fluids in heated horizontal flow, focusing on the impact of upstream heating history which has been rarely discussed. The Abe-Kondoh-Nagano (AKN) low Rek–ε turbulence model was employed, covering a wide range of upstream conditions: upstream heating length ranging from 10d (d is tube diameter) to 200d, and upstream heat flux up to 4.5 times that of the downstream test section. The results revealed that heating history didn't matter when upstream Grq/Grth < 5. For upstream mixed convection of Grq/Grth = 10–220, heating history had a significant effect on the downstream flow, causing a maximum 50 %–60 % increase in heat transfer coefficients within an affected length up to 100d. When the downstream flow was forced convection, thermophysical property variations mainly contributed to the above enhancement. Meanwhile for downstream mixed convection, upstream heating history notably enhanced turbulent intensity, further improving heat transfer. The upstream heating length was identified as a crucial factor influencing both forced and mixed convections downstream. Negligible differences were observed when the heating length was less than 20d. On the other hand, the radial distribution of flow and thermal fields remained constant beyond a critical heating length, indicating the achievement of a pseudo-fully-developed state with identical heat transfer behavior. Results of this work confirm that the effect of upstream heating history is closely tied to thermal developing length and holds significant importance in the thermal design of vapor generators.

Evaluating sacha inchi (Plukenetia volubilis) oil stability and physicochemical properties: A comparison between conventional extraction and supercritical fluids

This study aimed to compare the effects of two extraction techniques (conventional n-hexane and supercritical CO2) on the oil extraction yields, fatty acids profile, anti-hyaluronidase activity, oxidative stability, and in vitro bioactivities of oils from Sacha Inchi (Plukenetia volubilis). Higher oil extraction yield (99 %) was achieved using the SC-CO2, although similar fatty acids profiles were depicted between both treatments (p < 0.05). The SC-CO2 oil presented higher anti-hyaluronidase (31 %) activity, but lower oxidative stability (5.05 h) compared to the solvent extraction (10 %, and 5.3 h, respectively). In vitro assays further revealed that the best human normal colon cells (FHC) cell viability (100 %), anti-inflammatory (50 % lower NO production), and antioxidant (20 % ROS reduction) activities were consistently observed in both extraction treatments at concentrations of 50 μg/mL and higher. These findings highlight the potential of supercritical CO2 extraction in yielding Sacha Inchi oil with enhanced bioactive properties without the disadvantages of the use of organic solvents extraction.

Characterization of a Soft Ionization by Chemical Reaction in Transfer Ion Source Hyphenated With Supercritical Fluid Chromatography-Tandem Mass Spectrometry.

A commercially available dielectric barrier discharge ionization (DBDI) source was tested with supercritical fluid chromatography-mass spectrometry (SFC-MS). The compound mixture investigated comprised caffeine, theobromine, theophylline, uracil, testosterone, and pyrene, diluted in methanol. Dynamic response ranges were evaluated with multiple injections at different concentrations. Precision studies demonstrated the robustness and sensitivity of the ionization source across a concentration range of 10-1000ng/mL. Results from this experiment showed linear regression of 0.99 or greater for all analytes tested over the range with a relative standard deviation (RSD) of less than 10% down to 10ng/mL for all analytes except theobromine, which had an RSD of less than 10% down to 25ng/mL. Notably, this study marks the first investigation of sensitivity for coupling a commercial DBDI source with SFC; a limit of detection less than 1ng/mL was achieved for all compounds. This study demonstrates chromatographic separation by SFC and MS analysis for compounds that ionize poorly using traditional atmospheric pressure ionization, such as polycyclic aromatic hydrocarbons. Combining SFC with the DBDI source opens promising avenues for analyzing compounds that were previously challenging to characterize with standard atmospheric pressure ionization techniques.

Physicochemical Properties, Heavy Metal and Pesticide Contaminations, and Microbial Limit Tests of Cannabis Oral Drops

Cannabis, a medicinal herb renowned for its therapeutic potential, is utilized in the treatment of various ailments, including the stimulation of appetite in cancer patients. In Thailand, the predominant dosage form is oral drops; however, the absence of robust quality control measures for these products poses significant health risks to patients. The primary objectives of this study were to formulate and evaluate cannabis oral drops, with a comprehensive evaluation encompassing physicochemical properties such as appearance, pH, Δ9-tetrahydrocannabinol, and cannabidiol contents. Furthermore, heavy metals (specifically arsenic, cadmium, and lead), pesticides (including pyrethroids, organochlorines, organophosphates, and carbamates), and microbial contaminations (Staphylococcus aureus, Clostridium spp., and Salmonella spp.) were evaluated. The results revealed that the optimal formulation, comprising cannabis extract derived from supercritical carbon dioxide fluid, vitamin E acetate, and medium-chain triglyceride oil, exhibited a pH of approximately 4.0, a Δ9-tetrahydrocannabinol content of approximately 27 mg/mL, and a cannabidiol content of approximately 9 mg/mL. Furthermore, there were no heavy metals or pesticides detected. Microbial limit tests demonstrated the absence of Staphylococcus aureus, Clostridium spp., and Salmonella spp. In conclusion, this endeavor successfully achieved the development of high-quality cannabis oral drops, showcasing the potential for safe and therapeutic use.

Utilizing cocoa bean husk residues from supercritical extraction for biofuel production through hydrothermal liquefaction

This study aimed to develop an efficient method for converting residual biomass into biofuel through a process that combines supercritical fluid extraction and hydrothermal liquefaction. The study analyzed the compositional changes in the biomass residues using various co-solvents and assessed their potential for biofuel production. After hydrothermal liquefaction, the liquid biofuel produced showed a decrease in the H to C ratio from 1.7 to 1.6 and a reduction in the O to C ratio from 0.5 to 0.2, compared to the unprocessed feedstock, indicating a favorable alteration in elemental composition for biofuel production. Notably, residues extracted with supercritical CO2 and ethanol had the lowest yield, while those extracted with CO2 and water achieved the highest energy recovery at 101.5%. These findings suggest that integrating supercritical fluid extraction with hydrothermal liquefaction is an environmentally sustainable and efficient approach, significantly advancing the development of sustainable biofuels.

Experimental investigation of the pressure drop of CO2 flow at supercritical pressures in a heated 4 mm smooth pipe with different orientations

The application of supercritical fluids as an alternative heat transfer medium in thermal processes is becoming increasingly important, whereby the understanding of their pressure drop characteristics is essential for the process and component design. With a total of 96 experiments, this publication shows a systematic analysis of the pressure drop of CO2 flow at supercritical pressures in a heated smooth pipe with an inner diameter of 4 mm, at a pressure of 7.75 MPa, mass fluxes up to 2000 kg/m2s and heat fluxes up to 235 kW/m2. The hydrostatic pressure drop accounts for between 4 % and 24 % of the total pressure drop and the pressure drop due to flow acceleration for between 12 % and 30 %, with the frictional pressure drop accounting for the largest percentage. It was found that the Filonenko correlation can predict the pipe friction pressure drop in the investigated parameter range with a mean absolute deviation of 7 %.

Current Perspectives on Development and Applications of Cocrystals in the Pharmaceutical and Medical Domain.

In recent years, the design of pharmaceutical cocrystals has garnered significant attention. The process of cocrystallization offers a remarkable opportunity to develop drug products with enhanced properties such as improved stability, solubility, hygroscopicity, dissolution rate, and bioavailability. This detailed review delves into this evolving area, thereby exploring its relevance in pharmaceutical formulation by defining cocrystals and their practical applications and also by discussing methods for their preparation as well as characterization. It also contrasts traditional and innovative techniques for cocrystal formation. Historically, cocrystals have been synthesized using methods like solvent evaporation, grinding, and slurry techniques; however, each has its own set of limitations under specific conditions. The latest trends in cocrystal formation lean toward more advanced approaches such as spray-drying, hot melt extrusion, and supercritical fluid technology, as well as the cutting-edge technique of laser irradiation. The aim behind developing new methods is not just to address the limitations of traditional cocrystallization techniques but also to streamline the process by introducing simpler steps and enabling a continuous production workflow for cocrystal products. In general, this full-length review article offers a report on various techniques available for the creation of pharmaceutical cocrystals, along with the methods for their evaluation. Moreover, it includes reporting developments and diverse applications of cocrystals along with the commercially available cocrystals in the pharmaceutical as well as medical domains.

Capillary electrochromatography applied to the separation of enantiomers utilizing packed capillary columns with silica-vancomycin. A tutorial

The separation and analysis of chiral compounds is an important topic in various fields such as research, pharmaceutical industry, food control, agrochemistry, biochemistry, forensics and toxicology, etc. The interest in the mentioned fields is mainly due to the fact that enantiomers could react with the chiral environment. Therefore, their separation and analysis are a challenging issue because the use of these compounds can be related to humans and animals’ lives as well as to the environment (e.g., soil and water). Their separation can be performed with different analytical techniques such as high-performance liquid chromatography, gas chromatography, supercritical fluid chromatography, and microfluidic technique (capillary electrophoresis and capillary electrochromatography-CEC). Usually the direct resolution method is applied making use of a chiral stationary phase (CSP). This tutorial is aimed at illustrating the main features of CEC using a packed capillary, e.g., employing a silica-vancomycin CSP. The synthesis of the CSP, the instrumentation of CEC coupled with UV and mass spectrometry detectors, method optimization, and two selected applications are presented and discussed.

Advantages of online supercritical fluid extraction and chromatography hyphenated to mass spectrometry to analyse plastic additives in laboratory gloves

Plastic additives are introduced in plastic material formulations, along with organic polymers, to offer different properties such as stability, plasticity or color. However, plastic additives may migrate from the plastic material to the content (in case of plastic containers) or to the material in contact with the plastic, like human skin. In the case of plastic medical devices, this migration is of particular interest, as plastic additives may be deleterious to health. In the present paper, we examined the interest of combining supercritical fluid extraction (SFE) to supercritical fluid chromatography (SFC) hyphenated to mass spectrometry (MS) in an online system to characterize plastic additives in laboratory gloves, taken as samples of medical devices. A set of target compounds comprising 18 plasticizers, 4 antioxidants and 2 lubricants was defined and their detectability with MS was examined, where it appeared that electrospray ionization (ESI) provided better detectability than atmospheric pressure chemical ionization (APCI). After examining possible stationary phases with the help of Derringer desirability function, an isocratic chromatographic method (CO2:methanol 95:5) was developed on Shim-pack UC Phenyl column. The extraction method was examined with a 3-level full factorial design of experiments to optimize the extraction temperature (40 °C) and pressure (200 bar). The online SFE-SFC-MS method was compared to offline methods where the samples were extracted with liquid solvents at atmospheric pressure or high pressure then analysed with SFC-MS. In all cases, offline methods showed significant contaminants (like the oleamide lubricant) issuing from laboratory plastic materials as nitrogen drying station, syringes and filters, while the online method allowed a complete elimination of laboratory contaminations. Furthermore, the online method saved time, solvents and laboratory consumables. It will also show that transferring a compressible fluid from a loading loop is favourable to high efficiency, as the resulting chromatographic peaks are much thinner than when transferring a liquid. Compared to injecting liquid heptane, the efficiency increase was 3.4-fold, while compared to injecting liquid methanol (a common practice in SFC), the efficiency increase was 13-fold. Finally, the additive composition of different laboratory gloves was compared.

Reactive molecular dynamics simulations of poly(vinyl alcohol) gasification in supercritical carbon dioxide

Supercritical fluid gasification technology, as an environmentally friendly technology, can convert organic components of plastic waste into fuels and chemical materials. Moreover, the utilization of CO2 as the gasification environment holds significant importance for reducing carbon emissions. To better comprehend the microscopic mechanism of plastic gasification in supercritical environment, this sthdy used the Reactive Force Field (ReaxFF) molecular dynamics method to study the gasification process of long-chain poly(vinyl alcohol) molecule in supercritical H2O/CO2 under different reaction conditions. The result illustrated that during the gasification process, poly(vinyl alcohol) initially depolymerized into multiple long carbon chain (C5+) molecular fragments. Subsequently, these fragments underwent cleavage into short carbon chains and various gaseous small molecules. In this reaction, O radicals generated by CO2 decomposition play a crucial role in promoting the cleavage of plastic C–C bonds. In addition, through the analysis of the products and chemical bonds, we found that increasing temperature and prolonging reaction time significantly enhance the gasification efficiency and hydrogen production of plastics. Conversely, exceedingly high pressure inhibits the gasification reaction.

Interpretable machine learning-based prediction and analysis of supercritical fluid heat transfer characteristics at different boundary conditions

The study of the heat transfer characteristics of supercritical fluids is crucial for the safe and economical operation of supercritical energy systems. This study presents a new method to study the heat transfer characteristics of supercritical fluids, employing interpretable machine learning. Two back propagation neural network models are proposed for the prediction of heat transfer to supercritical fluid for the cases with given heat flux and given wall temperature, respectively. The particle swarm optimization algorithm was employed to search for the optimal hyperparameters, and the resulting accuracy was evaluated in comparison with that of the traditional empirical correlation and a number of machine learning models. Combining the SHAP interpretable algorithm with prediction models, the supercritical heat transfer mechanism is explored from the perspective of global and local prediction behaviors based on explainable models. The results demonstrate that the average error of two established neural network models on the test set is 0.47 % and 0.69 %. Furthermore, for vertical upward flow, the buoyancy and acceleration effects are of greater feature importance in heat transfer deterioration. They are the primary factors contributing to heat transfer deterioration behavior. The research method proposed in this study has certain reference significance for further study of the heat transfer characteristics of supercritical fluids.

Supercritical fluid impregnation of phenolic compounds from passion fruit bagasse in corn starch aerogels: Phase behavior and effect of operation mode

This work investigated the phase behavior of the system sc-CO2 + ethanolic extract of passion fruit bagasse (EEPFB) and the effect of operation modes on the supercritical fluid impregnation (SFI) of phenolic compounds from EEPFB in corn starch aerogels. The total reducing capacity, antioxidant capacity (FRAP and ORAC), piceatannol amount and SFI yield (%) were evaluated. Three of the four system compositions showed the formation of a solid phase. SFI in static mode provided the best TRC, FRAP, and ORAC results. There were no significant differences in the amount of piceatannol and yield (%). The nitrogen adsorption/desorption test possibly indicates the filling of the aerogel pores with EEPFB and images of the aerogel before and after SFI suggest the incorporation of phenolic compounds into the corn starch aerogels through precipitation.

In-depth phytochemical profiling of Roscoea purpurea (Kakoli): Comparative UHPLC-MS/QToF and GC-MS/MS analysis of supercritical CO2 fluid - and conventional solvent - based extractive processes

The remarkable biodiversity of medicinal plants worldwide highlights their significance in traditional and alternative medicine. Astavarga, a group of eight medicinal herbs from the Himalayan region of India, including Roscoea purpurea (commonly known as Kakoli), is esteemed in Ayurveda for its health-promoting and rejuvenating properties. In this comprehensive study, we aimed to develop and optimise robust UHPLC-MS/QToF (Ultra-high-performance liquid chromatography-mass spectrometry coupled with quadrupole time of flight) and GC-MS/MS (Gas chromatography-tandem mass spectrometry) methods to identify the phytochemicals in R. purpurea root hydromethanolic extract and essential oil. We also conducted a comparative assessment of supercritical fluid extraction and conventional solvent extraction methods for the first time in R. purpurea root, highlighting their relevance to the medicinal field. Using the UHPLC/MS-QToF method, we identified a total of fifty-six phytometabolites, while sixteen volatile constituents were discerned within the essential oil of R. purpurea by GC-MS/MS method. Among the volatile constituents, β-eudesmol (40.84 %), guaiac acetate (10.55 %), and γ-eudesmol (10.31 %) were emerged as the principal components. Our findings were further compared with the volatile constituents extracted via supercritical fluid extraction and conventional solvent extraction methods. Notably, our research unveiled the presence of a carotenoid metabolite, 15-methyl retinol, for the first time. Furthermore, our fatty acid analysis of the supercritical fluid extract revealed elevated levels of unsaturated fatty acids, particularly oleic and linoleic acids. The methods were validated in terms of system specificity also. The discovery of these well-recognised therapeutically active components in R. purpurea significantly enhances its potential, highlighting its unique profile among medicinal plants in the Himalayan region and its suitability for traditional Ayurveda.

Green preparation of biodegradable poly (butylene adipate-co-terephthalate) foam modified with bio-based epoxidized cardanol using supercritical fluid foaming

Poly (butylene adipate-co-terephthalate) (PBAT) foam is a potential alternative to conventional packaging materials. However, its wide adoption is hindered by issues such as low foaming–expansion ratios and shrinkage. A series of biodegradable epoxidized cardanol (EC)-modified PBAT foams were prepared using supercritical carbon dioxide (CO2) foaming. The addition of EC enhanced the crystallisation temperature and stiffness, and improved the rheological properties, thereby promoting polymer foamability. When the EC content reached 0.6 wt%, lightweight foams with the highest initial expansion ratio (Rv) of 48.4 were produced before shrinkage. N2 was introduced as a co-blowing agent to reduce shrinkage of the PBAT foams, resulting in the production of a microcellular foam with a stable Rv of 12.9. EC improved the foamability of PBAT while also introducing the co-blowing agent N2 to resist shrinkage. These findings can serve as valuable insights for the large-scale production of lightweight biodegradable foams.

Scenarios, prospects, and challenges related to supercritical fluid impregnation in the food industry: a scoping review (2018–2023)

Scenarios, prospects, and challenges related to supercritical fluid impregnation in the food industry: a scoping review (2018–2023)