Abstract This study investigates the aerodynamic design and analysis of a low aspect ratio, multistage, axial-flow sCO2 turbine for integration in power cycles for small modular reactors and concentrated solar power systems. The secondary flows developing across the flow path are analyzed using low- and high-fidelity modeling approaches, to evaluate their impact on aerodynamic performance. An in-house low-fidelity design tool (zturbo), developed at Politecnico di Milano and featuring multiple loss correlations, was coupled to a nonlinear optimization algorithm to create an optimized preliminary mean-line design (MLD) of a five-stage axial sCO2 turbine flow path, with an optimal total-to-total efficiency of 93.9%. Fully three-dimensional (3D) numerical simulations of the turbine first stage, featuring the lowest aspect ratio blade (approximately 0.5), were performed using both steady-state and time-resolved approaches. The impact of vortex–blade and vortex–vortex interactions on the stage efficiency was highlighted, with unsteady interactions causing 10% higher secondary losses compared to the steady-state model. Finally, fully 3D numerical simulations of the complete five-stage axial sCO2 turbine were performed to investigate the development of secondary flows in a multistage configuration. The secondary loss estimates obtained by the computational fluid dynamics (CFD) simulations were compared with those evaluated by applying multiple empirical loss correlations. Results indicate that literature-based empirical loss correlations provide acceptable performance estimates for the overall turbine performance, but a margin of improvement is evident in the estimate of secondary losses, which appear overly conservative for low aspect ratio blades. Conversely, industrial correlations developed in-house aligned more closely with high-fidelity results.

ABSTRACT Owing to inherent limitations such as low melt strength and slow crystallization rate, poly(4‐hydroxybutyrate) (P4HB) exhibits unsatisfactory foaming performance and oil adsorption capacity. Herein, a shear‐induced in situ fibrillation process is integrated with supercritical CO 2 foaming to fabricate P4HB/polyaryl polymethylene isocyanate (PAPI)/polyvinylidene fluoride (PVDF) foams. This strategy enhances the crystallization behavior and melt strength of chain‐extended P4HB, suppresses foam shrinkage, and improves both foaming ability and oil adsorption performance. The resulting foam achieves a maximum expansion ratio of 45.9 and a cell density of 5.8 × 10 12 cells/cm 3 . Notably, the foam with 2 wt% PVDF exhibits the highest oil adsorption capacity, reaching 28.1 g/g for CCl 4 . This work provides an effective strategy for overcoming the challenges of P4HB foaming and demonstrates significant potential for expanding its applications in oil adsorption and related fields.

Drug solubility in supercritical carbon dioxide (SC-CO2) plays a pivotal role in the development of particle engineering, drug loading, and solvent-free pharmaceutical formulations. However, experimental solubility determination in supercritical systems remains costly, time-consuming, and compound-specific. In this study, an interpretable data-driven framework is proposed to support pharmaceutical formulation scientists by accurately predicting drug solubility in SC-CO2 while elucidating the governing physicochemical factors. Multiple machine learning regressors, including Extreme Gradient Boosting and Support Vector Regression, were developed and further integrated into an ensemble strategy to enhance robustness and generalizability. Model performance was systematically optimized using bio-inspired metaheuristic algorithms, enabling efficient hyperparameter selection across complex, nonlinear search spaces. Beyond predictive accuracy, model interpretability was emphasized through sensitivity-based and amplitude-based feature analyses, revealing the dominant molecular descriptors and process conditions influencing solubility behavior. The results demonstrate that the proposed framework not only improves solubility prediction accuracy but also provides mechanistic insights relevant to drug selection, formulation feasibility, and supercritical processing design. This work establishes a practical computational tool for accelerating pharmaceutical development pipelines involving supercritical fluid technologies.

Individual polyethylene glycol (PEG) oligomers' in vivo fate is crucial for evaluating polymer-based therapeutic safety. Herein, a high-throughput UPC2-MS/MS method was developed for the oligomer-resolved excretion kinetics of PEG600 (n = 10-17) in rats. By optimizing supercritical CO2 chromatography and utilizing ammonium adducts ([M+NH4]+), baseline separation of eight oligomers was achieved within 2.4 min, significantly enhancing efficiency for bioanalysis. This platform significantly enhances analytical capacity, enabling the efficient processing of large-scale biological sample sets required for mass balance studies. Application of this method revealed distinct molecular-weight-dependent elimination. Specifically, 72-h urinary recovery showed a complex non-linear relationship, peaking at n = 10 (71.9%) and n = 16 (72.7%). Simultaneously, total cumulative recovery (urine and feces) decreased progressively from >95% (n = 10, 11) to 75.3% (n = 17). This reduction suggests enhanced tissue sequestration or metabolic biotransformation for larger oligomers. This high-resolution profiling uncovers subtle elimination differences obscured in bulk analysis, providing critical pharmacokinetic insights for PEG excipients.

Supercritical CO 2 (SCO 2 ) centrifugal compressors are pivotal components in next-generation high-efficiency power cycles (e.g., Brayton cycles), enabling greater than 50% thermal efficiency and compact power block designs essential for sustainable energy systems. This study addresses a critical reliability challenge by optimizing dry gas seal (DGS) groove designs for these compressors. Using validated 3D CFD simulations, incorporating k-ω SST turbulence model and Redlich-Kwong real gas equation of state, the performance of four industrial groove geometries (spiral, oval, fish-tail, and tree-type) are evaluated. Results demonstrate that the tree groove minimizes leakage (29.7% reduction vs. spiral) through tortuous flow paths, directly supporting emissions control and operational economy in power cycles. Conversely, spiral grooves maximize opening force and gas film stiffness (6.2% higher stiffness vs. tree), ensuring stable non-contact operation crucial for compressor reliability at extreme pressures. Oval and fish-tail grooves offer intermediate trade-offs. Thermal analysis reveals considerable localized high temperature zones due to viscous dissipation and adiabatic compression, a key consideration for material longevity. This work establishes that groove selection fundamentally balances leakage rate (optimized by tree grooves) against hydrodynamic stability (maximized by spiral grooves). These findings provide practical guidelines for enhancing DGS performance in SCO 2 compressors, directly contributing to the viability of high-efficiency, low-emission power generation.

Concerns about sustainable food production, renewable energy, and environmental preservation have made vegetable oil extraction technology more and more significant. 235 publications were obtained from the Scopus database using keywords like “vegetable oil extraction,” “solvent extraction,” “green extraction,” and “biosolvent.” This study provides a bibliometric overview of research on vegetable oil extraction from 2016 to 2024. China contributed 50.6% of the 87% growth in research production, followed by the USA, Brazil, Italy, and Spain. Zhejiang University, Indian Institute of Technology, and Islamic Azad University were the most productive universities. With 53 publications, Food Chemistry was the most popular journal. Journal of Chromatography A came in second with 24 and Journal of Oleo Science third with 15. Additional noteworthy journals were Food Analytical Methods (8), Molecules and Talanta (9 each), Journal of Separation Science (10), and Ultrasonics Sonochemistry (13). Supercritical CO₂, ultrasound, and microwave-assisted extraction are examples of advanced techniques that are being used more and more in conjunction with traditional methods. These techniques preserve over 85% of bioactive compounds, improve yields by 15–40%, and use less solvent by 30–50%. The data demonstrates a global trend toward the production of high-quality, ecological, and energy-efficient vegetable oils.

CO2 geological sequestration in deep, unmineable coal seams is a key technology for carbon capture, utilization, and storage (CCUS). This study focuses on the No. 3 major high-rank coal reservoir in the southern Qinshui Basin, utilizing high-pressure and high-temperature CO2 isothermal adsorption experiments coupled with multiple adsorption models (Langmuir, BET, D-R) to establish a sequestration capacity calculation model. The study investigates CO2 sequestration mechanisms and evaluates potential and favorable zones for sequestration. The results show that CO2 sequestration mechanisms vary with temperature and pressure conditions. Specifically, adsorption dominates in the middle-deep subcritical zones but decreases with depth, while free-phase sequestration increases in the deep supercritical zone. Regarding model applicability, the BET model best fits supercritical CO2 adsorption, effectively capturing the sharp adsorption increase near the critical point. Quantitative assessments indicate that the optimal sequestration depth is 800-1100m, with a total sequestration potential of 575.5 Mt, 65.4% of which is in the deep supercritical zone. The supercritical zone's sequestration abundance reaches 956.1 × 103 t/km2, representing a 53.5% increase over the subcritical zone. Furthermore, adsorption and free-phase sequestration account for over 99% of the total potential, while dissolution and mineralization are negligible. Based on these evaluations, two deep coal reservoir units in the northern region are identified as optimal sequestration zones, coinciding with areas of high CBM potential, which could facilitate integrated CBM development and CO2 sequestration. This study provides a theoretical and methodological framework for evaluating CO2 sequestration potential and identifying favorable zones in deep coal reservoirs.

In this study, the antifungal activities of essential oil, supercritical carbon dioxide (SC-CO₂) extract, methanol extract, and SC-CO₂+ethanol extract obtained from Thymbra spicata L. were evaluated in vitro against the soilborne fungal pathogens Sclerotinia sclerotiorum, Macrophomina sp., Rhizoctonia solani, and Fusarium oxysporum, which cause substantial economic losses in cultivated plants. The chemical profiles of the extracts were determined using GC-MS. Carvacrol and p-cymene were identified as the major constituents of the SC-CO₂ and SC-CO₂+ethanol extracts, accounting for 86.79% and 4.70%, respectively, of the SC-CO₂ extract and 72.07% and 4.6%, respectively, of the SC-CO₂+ethanol extract. Among the essential oils, carvacrol (89.61%) and trans-β-caryophyllene (1.86%) were identified as the predominant constituents, whereas the methanol extract was characterized by a greater proportion of non-volatile constituents, mainly carvacrol (33.93%) and linoleic acid (21.19%). Antifungal bioassays were conducted using the contact effect method at concentrations of 0.25, 0.50, 1.00, 2.00, and 4.00µl/ml. T. spicata essential oil (1.00, 2.00, and 4.00µl/ml) and the SC-CO₂ extract (2.00 and 4.00µl/ml) completely inhibited (100%) the mycelial growth of S. sclerotiorum in a dose-dependent manner, indicating fungicidal activity. Similarly, complete inhibition of Macrophomina sp. was observed with essential oil at 2.00 and 4.00µl/ml and with SC-CO₂ and SC-CO₂+ethanol extracts at 4.00µl/ml. The essential oil and SC-CO₂ extracts (1.00, 2.00, and 4.00µl/ml) completely inhibited the mycelial growth of R. solani and F. oxysporum, demonstrating fungicidal activity. These differences in inhibition rates were statistically significant (p ≤ 0.05). In contrast, the methanol extract had no inhibitory effect on any of the tested concentrations. ADMET analyses were performed to assess the acute toxicity profiles of carvacrol and p-cymene. Molecular docking against the 6CR2 target protein was conducted to assess ligand-protein interactions. Among the essential oil constituents evaluated, carvacrol and p-cymene exhibited the most favorable binding energies, supporting their potential as lead antifungal compounds.

A naringenin-rich extract was obtained from Mexican oregano (Lippia graveolens Kunth) by supercritical CO2 extraction and subjected to simulated gastrointestinal digestion to evaluate its potential to mitigate oxidative stress, reduce nitric oxide (NO) production, and enhance glucose uptake, an indicator of insulin resistance. Even after the simulated digestion, the extracts still showed activity, as the digested supercritical extract showed cellular antioxidant activity in colorectal adenocarcinoma (Caco-2) cells higher than 80%, increased glucose uptake in hepatocellular carcinoma HepG2 cells with insulin resistance by 29.9% and decreased NO production in 38.1% in murine macrophages (RAW 264.7). The methanolic extract showed similar results but led to higher NO production. In general, supercritical CO2 extraction yields higher flavonoid content in oregano extract than conventional methanolic extraction, as reflected in the biological activities; moreover, the green nature of the process supports the development of functional ingredients.

Bacterial cellulose (BC) pellicles were produced from Acetobacter xylinum using a simple, additive-free, and low-cost static cultivation method consistent with sustainable and green bioprocessing principles. Two post-synthesis drying routes were compared: supercritical carbon dioxide (scCO2) drying following acetone solvent exchange and direct lyophilization without chemical additives or pre-freezing. The resulting BC aerogels and cryogels were characterized by SEM, confocal microscopy, BET analysis, FTIR spectroscopy, EDS, and geometrical evaluation with a particular emphasis on nanostructure, porosity, and network integrity. scCO2-dried BC aerogels exhibited a well-preserved three-dimensional nanofibrillar network, achieving a BET surface area (123m2/g), large pore volume (0.36cm3/g), and an average pore diameter of 10nm. Confocal microscopy revealed higher surface roughness (Rz up to ~ 58μm), reflecting a more developed and heterogeneous surface topography. Lyophilized BC cryogels showed lower surface area (51m2/g) and pore volume (0.13cm3/g); however, SEM and confocal analyses indicated that the nanofibrillar network and three-dimensional architecture were largely retained, with only localized fibril aggregation and reduced roughness (~ 28-30μm). EDS confirmed high chemical purity in scCO2-dried aerogels, while minor inorganic traces detected in cryogels were attributed to residual components from the tea-based culture medium. Although scCO2 drying provided slightly superior structural preservation and textural properties, the porous architecture remained comparable between the two methods. Overall, additive-free BC pellicles produced by static cultivation and processed via limited pre-freezing followed by lyophilization provided a structurally comparable and more sustainable alternative, offering a practical balance between textural performance and processing simplicity.These findings underscore the potential of simplified drying strategies for the sustainable fabrication of BC-based porous materials without compromising structural functionality. .

Basalt is a promising reservoir for CO2 mineralization due to its favorable mineral composition. Understanding the distribution patterns and spatial development of carbonate minerals within basalt during supercritical CO2 (scCO2) reaction is critical for evaluating its storage potential. In this study, a novel in situ dynamic core-flooding setup, integrated with scanning electron microscopy (SEM), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), and a suite of complementary characterization analyses, was employed to investigate mineral dissolution, cation release, and carbonate precipitation, with particular focus on the distribution patterns and spatial scale of carbonate coatings. After CO2 injection, the solution pH rapidly drops and stabilizes between 6.32 and 6.75, facilitating the release of Ca2+ and Mg2+ from mineral dissolution. Secondary carbonate formation initiates after 3 days, confirmed by intensified carbonate-related infrared bands and C 1s binding energy. These carbonates predominantly form on pyroxene surfaces and expand progressively with reaction time, while plagioclase shows only subtle dissolution and precipitation. The combination of dissolution and precipitation increases surface roughness on pyroxene, whereas plagioclase surfaces become smoother due to limited reactivity. Pyroxene is identified as the primary host mineral for mineralization, frequently developing well-crystallized calcite coatings. Quantitative analysis reveals that after 7 days of reaction, the carbonate coatings on pyroxene reach a spatial volume of 1499.21 × 109 nm3. This research highlights the crucial role of reaction duration and mineralogical factors in controlling carbonate mineralization within basalt and provides valuable insights into the mechanisms and potential of basalt CO2 mineralization.

Aqueous organic batteries provide a sustainable and metal-free alternative to conventional electrochemical storage, with performance often limited by modest active material loading and incomplete utilization inside porous carbon hosts. We report a simple all-organic full cell in which supercritical CO2 (scCO2) impregnation loads halogenated quinones into activated carbon (AC) and reorganizes the interface in a way that accelerates charge transfer. Using a minimal formulation, 1,5-dichloroanthraquinone is incorporated at approximately 38 wt % loading in the quinone/AC composite (prior to binder addition) with full electrochemical utilization, corresponding to high-density filling of the micropores rather than a high overall active-mass fraction, and serving as evidence of effective pore accessibility. Micropore analysis indicates about 90% of a micropore-limited upper bound. Small-angle X-ray scattering shows an increase in the high-q electron density correlation length, consistent with strengthened π-π stacking and denser intrapore packing under supercritical conditions. We extracted interfacial electronic state information that can change with the impregnation route: comparative C K-edge X-ray absorption and X-ray photoelectron spectroscopy reveal core-level shifts consistent with a modified electronic environment and enhanced interfacial polarization in the scCO2-impregnated samples relative to liquid-impregnated controls; confinement- and packing-related effects may also contribute. In aqueous full cells, the supercritical route gives a 60% increase in energy density and a clearly improved rate response relative to liquid-phase impregnation, while retaining 95% of the capacity after 1000 cycles; electrochemical impedance spectroscopy likewise shows a lower apparent charge transfer resistance for electrodes fabricated via supercritical impregnation, indicating faster interfacial kinetics. Taken together, these results demonstrate that scCO2 impregnation promotes π-π-stacking-driven intrapore ordering and near-complete utilization in porous carbon quinone electrodes, translating nanoscale organization into device-level gains in a simple metal-free aqueous system.

Eleutherococcus senticosus extracts through a supercritical CO2 extraction process for antioxidant application

Supercritical carbon dioxide (scCO₂) is an environmentally friendly coolant in machining, addressing concerns associated with traditional metalworking fluids. In medical component manufacturing, selecting an appropriate coolant is crucial for ensuring contamination-free parts, which scCO₂ achieves by leaving no residue upon sublimation. Computational Fluid Dynamics (CFD) simulations offer valuable insights into the hydraulic efficiency of coolant delivery systems, essential for optimizing nozzle design and cooling effectiveness in internal cooling milling tools. This study investigates scCO₂ discharge and dispersion through internal milling tool nozzles in cryogenic machining, emphasizing CO₂ solidification and phase transitions from supercritical to solid CO₂ and gas phases. Utilizing ANSYS CFX software and extended real gas property (RGP) tables, the research examines scCO₂ behavior under various operational conditions. The extension of RGP tables accommodates phase transitions during cooling, addressing challenges in determining CO₂ properties in supercritical and sub-triple-point states, where solid CO₂ forms under atmospheric pressure. Experimental validation shows good agreement between simulated and observed mass flow rates and flow characteristics, with relative percentage errors of 7.7% for mass flow rate and 0.7% for minimum temperature upon expansion. Additionally, the simulation predicted a solid CO₂ mass fraction of up to 0.28 in the expansion zone, confirming the model’s ability to capture complex phase transitions. These simulations provide accurate and computationally efficient insights for tool design and optimization, overcoming challenges in determining CO₂ properties under extreme conditions.

Selective ion transport is essential for many applications of membrane separation, such as rare metal and high-value element extraction from complex ionic sources. However, efficient regulation of permeability-selectivity remains a major challenge for advanced ionic transport membranes. Herein, we demonstrate that supercritical CO2 (ScCO2) drying combined with crown ether functionalization enables precise modulation of crystallinity and ion-specific affinity in covalent organic framework (COF) membranes. The pristine COF membrane prepared by solution casting was amorphous. Owing to its positively charged framework and sub-nanometer pores, the membrane exhibited a high Li+ transport rate over Mg2+ via a synergistic effect of size exclusion and electrostatic repulsion, resulting in a selectivity of 204. After ScCO2 drying, the crystallinity and structural ordering of the COF membrane were significantly enhanced, leading to a 1.5-fold increase in Li+ flux, accompanied by a moderate decrease in selectivity to 147. To compensate for this trade-off, 12-crown-4 (12C4) was introduced as a Li+ recognition agent into the ScCO2-treated membrane, restoring Li+/Mg2+ selectivity to 187 without compromising Li+ flux. Importantly, the selective Li+ transport performance was maintained in real salt lake brines. This structural-chemical co-regulation strategy provides a versatile approach for optimizing ion transport membranes in complex separation applications.

Natural gas represents a pivotal transitional clean energy resource, and biogenic coalbed methane (CBM) is ubiquitously distributed in coal reservoirs worldwide. In the context of carbon neutrality targets and the growing demand for large-scale commercial CBM exploitation, innovative technological solutions are urgently required. CBM bioengineering aims to substantially enhance CBM production by stimulating biomethane generation, promoting gas desorption, and improving reservoir permeability, while simultaneously enabling effective CO2 sequestration. The potential for biomethane generation is largely governed by the intrinsic physicochemical characteristics of coal, including aromatic structures, maceral composition, and pore-fracture architecture. In addition, hydrogeological conditions-such as geothermal gradients, pH variability, and redox potential-play critical roles in regulating microbial functional gene expression and metabolic enzyme synthesis. Core pretreatment strategies in coalbed gas bioengineering can be broadly classified into approaches that enhance coal bioconversion potential and those that optimize functional microbial consortia. Electric fields and conductive materials can influence microbial community structure by enriching electroactive microorganisms and facilitating interspecies electron transfer. In addition to engineered conductive interventions, reservoir environmental conditions also play an important role in shaping methanogenic community structure. Experimental observations under reservoir-relevant CO2 pressure and temperature conditions indicate that deep coalbed environments are associated with shifts in methanogenic community composition, including an increased relative abundance of hydrogenotrophic methanogens. These observations suggest that physicochemical conditions in deep coal seams may favor hydrogen-dependent CO2 reduction pathways, thereby supporting hydrogenotrophic methanogenesis and contributing to biomethane generation. The integration of supercritical CO2 with microbially acclimated stimulation fluids as an innovative reservoir fracturing strategy offers multiple advantages, including effective reservoir stimulation, permanent carbon sequestration, and sustainable biomethane generation. Future research should focus on modulating coal matrix bioavailability, optimizing microbial consortia, enhancing interspecies metabolic synergies, and advancing carbon fixation bioprocesses to facilitate the large-scale implementation of coalbed gas bioengineering systems. This review synthesizes recent advances in microbially mediated CBM enhancement and CO2 sequestration, with a particular focus on field-scale evidence and the key challenges that must be addressed for large-scale implementation.

Evaluation of drug loading onto MCM-48 via supercritical CO2 deposition: Effects of drug type, temperature, and silica structure

Supercritical CO2 induced development of macropores/fractures in coal and associated mineral precipitation

Molecular dynamics study on the diffusion and dissolution of heavy oil in supercritical CO2 under high-temperature and high-pressure conditions

The therapeutic potential of tagitinin C, a potent sesquiterpene lactone from Tithonia diversifolia , is limited by its poor solubility and non-selective toxicity. This study aimed to evaluate the antitumor efficacy and safety of a tagitinin C-rich extract encapsulated in PEGylated liposomes (LPEG-ESTD), hypothesizing that this delivery system would enhance therapeutic outcomes by simultaneously activating mitochondrial apoptosis and ferroptosis pathways. The tagitinin C-rich supercritical co 2 extract was characterized (HPLC, FTIR) and encapsulated into PEGylated liposomes via thin-film hydration. The nanoformulation was thoroughly characterized (size, zeta potential, encapsulation efficiency, release profile and structural morphology by electronic microscopy). Efficacy was evaluated through cytotoxicity on B16F10 cells and an in vivo Sarcoma 180 model. Mechanistic pathways and safety were assessed via histopathological and immunohistochemical analyses (Ki-67, TUNEL, caspase-3, Bcl-2, Bax, NF-κB, NRF2). The optimized LPEG-ESTD formulation exhibited a nanometric size (∼120 nm), high encapsulation efficiency (>90%), and sustained release. It significantly enhanced cytotoxicity in vitro and potently inhibited tumor growth in vivo . Mechanistic studies revealed the nanoformulation activated mitochondrial apoptosis (increased TUNEL, caspase-3, Bax; suppressed Ki-67 and NF-κB) and induced ferroptosis (upregulated NRF2). Crucially, the liposomal system effectively mitigated the systemic toxicity of the free extract. This study demonstrates that PEGylated liposomes are a highly effective delivery system for a supercritical CO 2 -extracted phytotherapeutic. The LPEG-ESTD nanoformulation represents a promising strategy for cancer treatment by concurrently inducing apoptosis and ferroptosis, underscoring the value of advanced delivery systems in enhancing the efficacy and safety of natural anticancer compounds.