Licorice (Glycyrrhiza glabra L.) is a rich source of phytochemicals and bioactive compounds (BCs), and growing interest in plant-derived BCs has increased attention toward efficient extraction strategies. Extraction methodology plays a critical role in determining yield, efficiency, and sustainability. This systematic review evaluates the effectiveness of conventional and green extraction techniques for isolating BCs from licorice. A total of 42 eligible studies were identified from multiple databases, focusing on extraction, analysis, and identification of licorice BCs. Conventional methods, including Soxhlet and maceration, generally yielded 24.32-37.63 mg/g of glycyrrhizic acid, requiring prolonged extraction times (5-12 h) and large solvent volumes. In contrast, green extraction techniques significantly enhanced extraction efficiency within shorter durations (3-120 min). Glycyrrhizic acid yields ranged from 28.06-217.7 mg/g for ultrasound-assisted extraction, 22.6-45 mg/g for microwave-assisted extraction, 18.5-19.5 mg/g for subcritical water extraction, 340-544 mg/g for supercritical CO2 extraction, 20.99 mg/g for pressurized liquid extraction, and 43.78 mg/g for infrared-assisted extraction. These variations highlight the influence of operational parameters such as temperature, time, solvent characteristics, and solid-liquid ratio. Overall, green extraction methods offer superior performance and environmental advantages, representing promising alternatives for sustainable and large-scale recovery of licorice BCs.

The valorization of Camellia japonica flower varieties through the green extraction of their bioactive components is addressed. Microwave hydrodiffusion and gravity (MHG) can be an efficient and rapid pretreatment to dry the petals; for example, in the Royal Velvet variety, the energy consumption was 16 times lower compared to air drying. The hydrolates obtained in this stage represented only 0.5mg gallic acid equivalents/g flower, but some of the fractions contained up to 10 times higher and a Trolox equivalent antioxidant capacity (TEAC) value equivalent to 0.4g Trolox/g extract. The dried solids were extracted using 96% ethanol to yield around 30% solubles, which was 50% higher than the extraction yield from the air-dried samples. The MHG dried solids were treated with supercritical CO2 to yield up to 2.4% of an extract containing phenolics and lipids with a favorable omega-3 to omega-6 ratio. The residual solids from supercritical extraction were further processed with microwave heated pressurized hot water for 5min at various temperatures. The 200 °C extract achieved a solubilization of 50% of the material, obtaining a product with 22% phenolic content, almost 30% of the antiradical capacity of Trolox, a minimum inhibitory concentration (MIC) value of 8mg/mL against Staphylococcus aureus, and contained mainly organic acids, tannins like (epi)catechin gallate and B-type (epi)catechin oligomers, and prodelphinidins like (epi)gallocatechin-O-hexoside and (epi)catechin-(epi)gallocatechin gallate. The obtained extracts were proposed for incorporation onto starch films. The results confirm the potential of non-toxic solvents to achieve a complete valorization of this resource.

CO2 pipeline transportation is a core link in the CCUS (Carbon Capture, Utilization, and Storage Technology) industry. Ensuring the flow safety of CO2 pipelines under transient conditions is currently a key and challenging issue in industry research. This paper focuses on the phase migration and safety control during the shutdown process of supercritical carbon dioxide pipelines. Taking a supercritical carbon dioxide transportation pipeline in Xinjiang Oilfield, China, as the research object, a hydro-thermal coupling model of the pipeline is established to simulate the pipeline and elucidate the coordinated variation patterns of temperature, pressure, density, and phase state. It was found that there were significant differences in the migration paths of the CO2 phase at different positions. The accuracy of the simulation results was verified through the self-built high-pressure visual reactor experimental system, and the influences of the initial temperature, initial pressure, and ambient temperature before pipeline shutdown on the slope of the phase migration path were explored. The phase migration line slope prediction model was established by using the least squares method and ridge regression method, the process boundary ranges and allowable shutdown time ranges for pipeline safety shutdowns in both summer and winter were further established. The research results show that when the pipeline operates under the low-pressure and high-temperature boundary, the CO2 in the pipeline vaporizes earlier from the starting point after the pipeline is shut down, and the safe shutdown time of the pipeline is shorter. There is a clear safety operation window in summer, while vaporization risks are widespread in winter. The phase migration path prediction formula and the safety zone division method proposed in this paper provide a theoretical basis and engineering guidance for the safe shutdown control of supercritical carbon dioxide pipelines, which can help reduce operational risks and lower maintenance costs.

Abstract This study examines nickel electroplating in supercritical carbon dioxide (scCO₂)-emulsified nickel sulfamate baths, focusing on the effects of CO₂ volume fractions (10–80 vol.%) at a current density of 0.12 A/cm². The inclusion of scCO₂ significantly enhanced film quality, even at high CO₂ concentrations. However, Faradaic efficiency (FE) decreased from 95% to 75% as CO₂ volume fractions increased, attributed to intensified hydrogen evolution reactions (HER) caused by more negative deposition potentials and the insulating scCO₂ dispersed phase. Electrochemical analysis revealed pronounced potential fluctuations at higher CO₂ fractions due to intermittent electrode contact with the dispersed phase, which amplified HER and reduced the effective plating area. The conductivity of the scCO₂-emulsified bath followed the Maxwell–Garnett model, indicating isolated scCO₂ dispersed phases in a conductive medium. Despite reductions in FE and Vickers hardness (from 750 to 580 Hv), the films maintained smooth surfaces and fine grain sizes (~10 nm). These results demonstrate the potential of scCO₂ emulsification to produce high-quality nickel coatings and provide a framework for advancing electroplating in complex multiphase electrolytes.

Development of Process for Suppressing Elution of Sugars in Supercritical CO<sub>2</sub> Extraction for Decaffeination from Green Coffee Beans

The efficient development of coalbed methane (CBM) faces persistent challenges due to low recovery rates. While CO2 thermal displacement offers a promising approach, the pore–fracture structure (PFC) evolution and gas displacement mechanisms under temperature–pressure coupling remain insufficiently clear. To address this knowledge gap, the in situ, dynamic quantification of pore–fracture evolution during CO2 displacement was achieved by an integrated system with NMR and CT scanning, revealing the expansion, connection, and reconfiguration of coal PFC under temperature–pressure synergy and establishing the intrinsic relationship between supercritical CO2 (ScCO2)-induced permeability enhancement and methane displacement efficiency. Experimental results identify an observed transition in permeability near 80 °C under the tested conditions as a critical permeability transition point: below this value, permeability declines from 0.61 mD to 0.49 mD, reflecting pore structure adjustment; above it, permeability rises markedly to 1.18 mD, indicating a structural shift toward fracture-dominated flow. A “pressure-dominated, temperature-assisted” mechanism is elucidated, wherein pressure acts as the primary driver in creating macro-fractures and forming percolation pathways, while temperature—mainly via thermal stress—promotes micro-fracture development and assists gas desorption, offering only limited direct contribution to permeability. Although elevated injection pressure enhances permeability and establishes fracture networks, displacement efficiency eventually reaches a physical limit. To transcend this constraint, a synergistic production mechanism is proposed in which pressure builds flow channels while temperature activates microporous desorption. This study provides an integrated, in situ quantification of the pore–fraction evolution under high-temperature ScCO2 conditions. The elucidated synergy between pressure and temperature offers insights and an experimental basis for the design of deep CBM recovery and CO2 storage strategies.

Supercritical carbon dioxide (SC-CO2) power cycles offer a promising solution for offshore platforms’ gas turbine waste heat recovery due to their compact design and high thermal efficiency. This study proposes a novel parallel-preheating recuperated Brayton cycle (PBC) using SC-CO2 for waste heat recovery on offshore gas turbines. An integrated energy, exergy, and economic (3E) model was developed and showed good predictive accuracy (deviations < 3%). The comparative analysis indicates that the PBC significantly outperforms the simple recuperated Brayton cycle (SBC). Under 100% load conditions, the PBC achieves a net power output of 4.55 MW, while the SBC reaches 3.28 MW, representing a power output increase of approximately 27.9%. In terms of thermal efficiency, the PBC reaches 36.7%, compared to 21.5% for the SBC, marking an improvement of about 41.4%. Additionally, the electricity generation cost of the PBC is 0.391 CNY/kWh, whereas that of the SBC is 0.43 CNY/kWh, corresponding to a cost reduction of approximately 21.23%. Even at 30% gas turbine load, the PBC maintains high thermoelectric and exergy efficiencies of 30.54% and 35.43%, respectively, despite a 50.8% reduction in net power from full load. The results demonstrate that the integrated preheater effectively recovers residual flue gas heat, enhancing overall performance. To meet the spatial constraints of offshore platforms, we maintained a pinch-point temperature difference of approximately 20 K in both the preheater and heater by adjusting the flow split ratio. This approach ensures a compact system layout while balancing cycle thermal efficiency with economic viability. This study offers valuable insights into the PBC’s variable-load performance and provides theoretical guidance for its practical optimization in engineering applications.

The development of efficient, environmentally benign surfactants for stabilizing microemulsions in supercritical carbon dioxide (scCO2) remains a significant challenge for enhanced oil recovery (EOR), owing to the historical reliance on fluorinated compounds and the poor stability of conventional surfactants. Herein, we report a fluorine-free supramolecular surfactant system based on a β-cyclodextrin (β-CD) and polyethylene glycol (PEG) conjugate (denoted β-CD-PEG). This conjugate is further functionalized to enable dynamic covalent cross-linking at the interface. The surfactant system leverages host-guest chemistry to anchor the ionic liquid [Bmim][Pro] via inclusion complexation, while the PEG chain ensures scCO2 solubility. The optimized microemulsion achieves an ultralow interfacial tension of 1.8 mN/m and forms a rigid, elastic interfacial film (G' = 15.3 mN/m) through dynamic covalent cross-linking, ensuring long-term stability (>30 days). Core-flooding experiments demonstrate a reduction in the minimum miscibility pressure by 2.50 MPa and a 17.2% incremental oil recovery. The β-CD-PEG surfactant system also exhibits enhanced selectivity for extracting heavy oil components, leading to a viscosity reduction of up to 45.1% for heavy crude. This work establishes a paradigm for stabilizing complex fluid interfaces in scCO2 using supramolecular, dynamic, and fluorine-free surfactants, with significant implications for green and efficient chemical EOR processes.

Understanding how supercritical CO2 and water interact with mineral surfaces is essential for predicting the stability and sealing performance of geological storage formations. Yet, the combined effects of mineral surface chemistry and confined pore geometry on interfacial structure and fluid dynamics remain insufficiently resolved at the molecular scale. In this study, molecular dynamics simulations were employed to quantify how methylated SiO2, hydroxylated SiO2, and kaolinite regulate CO2–H2O interfacial behavior through variations in wettability and electrostatic interactions. The results show a clear hierarchy in water affinity across the three minerals. On methylated SiO2, the water cluster remains spherical and poorly anchored, with a contact angle of ~140°, consistent with the weakest water–surface Coulomb attractions (only −400 to −1400 kJ/mol). Hydroxylated SiO2 significantly enhances hydration, forming a cylindrical water layer with a reduced contact angle of ~61.3° and strong surface–water electrostatic binding (~−18,000 to −20,000 kJ/mol). Kaolinite exhibits the highest hydrophilicity, where water forms a continuous bridge between the two walls and the contact angle further decreases to ~24.5°, supported by the strongest mineral–water electrostatic interactions (−23,000 to −25,000 kJ/mol). Meanwhile, CO2–water attractions remain moderate (typically −2800 to −3500 kJ/mol) but are sufficient to influence CO2 distribution within the confined domain. These findings collectively reveal that surface functionalization and mineral type govern interfacial morphology, fluid confinement, and electrostatic stabilization in the sequence methylated SiO2 < hydroxylated SiO2 < kaolinite. This molecular-level understanding provides mechanistic insight into how mineral wettability controls CO2 trapping, fluid segregation, and pore-scale sealing behavior in subsurface carbon-storage environments.

Supercritical CO2 modifies deep coal reservoirs through the coupled effects of adsorption-induced deformation and geochemical dissolution. CO2 adsorption causes coal matrix swelling and facilitates micro-fracture propagation, while CO2–water reactions generate weakly acidic fluids that dissolve minerals such as calcite and kaolinite. These synergistic processes remove pore fillings, enlarge flow channels, and generate new dissolution pores, thereby increasing the total pore volume while making the pore–fracture network more heterogeneous and structurally complex. Such reservoir restructuring provides the intrinsic basis for CO2 injectivity and subsequent CH4 displacement. Both adsorption capacity and volumetric strain exhibit Langmuir-type growth characteristics, and permeability evolution follows a three-stage pattern—rapid decline, slow attenuation, and gradual rebound. A negative exponential relationship between permeability and volumetric strain reveals the competing roles of adsorption swelling, mineral dissolution, and stress redistribution. Swelling dominates early permeability reduction at low pressures, whereas fracture reactivation and dissolution progressively alleviate flow blockage at higher pressures, enabling partial permeability recovery. Injection pressure is identified as the key parameter governing CO2 migration, permeability evolution, sweep efficiency, and the CO2-ECBM enhancement effect. Higher pressures accelerate CO2 adsorption, diffusion, and sweep expansion, strengthening competitive adsorption and improving methane recovery and CO2 storage. However, excessively high pressures enlarge the permeability-reduction zone and may induce formation instability, while insufficient pressures restrict the effective sweep volume. An optimal injection-pressure window is therefore essential to balance injectivity, sweep performance, and long-term storage integrity. Importantly, the enhanced methane production and permanent CO2 storage achieved in this study contribute directly to greenhouse gas reduction and improved sustainability of subsurface energy systems. The multi-field coupling insights also support the development of low-carbon, environmentally responsible CO2-ECBM strategies aligned with global sustainable energy and climate-mitigation goals. The integrated experimental–numerical framework provides quantitative insight into the coupled adsorption–deformation–flow–geochemistry processes in deep coal seams. These findings form a scientific basis for designing safe and efficient CO2-ECBM injection strategies and support future demonstration projects in heterogeneous deep coal reservoirs.

The quantitative evaluation of the impact of wax-solid deposition on the CO2 displacement of high-pour-point oil has long been a challenge in gas-flooding experiments. This study employs slim tube experiments to simulate the displacement dynamics, and comprehensively evaluates the productivity/injectivity index formula and the GERG-2008 state equation. The results indicate that the fluctuations in this index remain stable within the 17–20 MPa range and become pronounced within the range of 30–40 MPa. The analysis of seepage velocity reveals an initial increasing trend for supercritical CO2 under the conditions of 30 MPa, 35 MPa, and 40 MPa, followed by inflection points at different time steps. The observed decline in seepage velocity inflection is associated with the occurrence of wax-solid deposition in high-pour-point oil. Notably, there is a significant surge in CO2 seepage velocity at 40 MPa during the latter stage of the experiment due to the release-blockage effect of supercritical CO2. To systematically analyze the influence of wax-solid on the CO2 displacement in high-pour-point oil, a methodological framework is established in this study. This approach enables precise analysis of displacement dynamic characteristics in the target areas and provides pressure parameters for oilfields.

The displacement patterns of CO2 are critical for assessing the storage capacity and efficiency of geological CO₂ sequestration, yet they remain underexplored across different pressures. For this purpose, an advanced high-pressure and high-temperature microfluidic platform is developed. By integrating a high-pressure chamber equipped with an observation window and high-strength glass chips, it is capable of operating at pressures up to 50 MPa and enables real-time observation of CO₂ displacement patterns at the pore scale. Experiments conducted across a pressure range from 1 bar to 16 MPa that enables the analysis of changes in displacement patterns, CO₂ saturation, displacement front length, and fractal dimension within heterogeneous porous media. The findings reveal that at low pressures and a flow rate of 0.1 mL/min, CO2 displacement was predominantly influenced by capillary forces, resulting in preferential invasion of larger pore throats. In contrast, at higher pressures, the displacement process was dominated by the synergistic effects of the viscous and capillary forces of supercritical CO₂. This results in the breakthrough of the main flow channel on the outlet side and tributary structures spanning its width on the inlet side. The platform offers robust means to investigate CO₂ displacement efficiency and optimize storage strategies.

Numerical studies are performed concerning the resistance behaviors of Betaine-type surfactant stabilized ScCO2 foam two phase displacement processes in porous media. Based on the specific foam rheology properties as well as the properly fit maximum bubble density nmax in the mechanistic Stochastic Bubble Population Balance (SBPB) model, the numerical studies reproduce satisfactorily the dynamic resistant characteristics in the foam flooding processes in reported laboratory works under various temperature and salinity conditions. Numerical results show the nmax value decreases from 630 to 80 mm−3 along with the increasing temperature from 60 to 120 °C, while increases from 140 to 1,470 mm−3 with the increasing salinity from 20,000 to 250,000 mg/L. The dominant role of the nmax parameter is revealed via the numerical study as higher nmax lead to higher foam apparent viscosity thus result in the higher flooding resistance factors. At last, the pressure distribution of the foam flooding process inside a 300 mm core is reproduced as well at meticulously fit nmax value. It is concluded the SBPB model could reveal the mechanisms, from aspects of the foam rheology as well as the bubble generation capacity, behind the high performance of Betaine-type surfactant stabilized ScCO2 foam resistant behavior in harsh reservoir conditions.

Against the backdrop of global energy transition and increasingly severe environmental conditions, developing clean and efficient energy systems has become crucial. This study aims to investigate a solar tower receiver tri-generation (STRT) system combining supercritical CO2 (S-CO2) Brayton cycle and organic Rankine cycle (ORC), with the objective of achieving the production of electricity, hydrogen, and oxygen. The modeling of the STRT system is completed by using Ebsilon, and the performance of the STRT system is analyzed. The results show that the output power and efficiency of the S-CO2 Brayton cycle are 62.29 MW and 48.3%, respectively. The net power and efficiency of ORC are 8.02 MW and 16.35%. The hydrogen and oxygen production rates of the STRT system are 183.8 kg·h−1 and 1470.4 kg·h−1, respectively. The STRT system shows stable and effective operation performance throughout the year. Through the exergy analysis, the exergy losses and exergy efficiencies of different components of the STRT system are obtained. The solar tower has the largest exergy loss (218.85 MW) and the lowest exergy efficiency (63%). The levelized electricity cost and the levelized hydrogen cost of the STRT system are 0.0788 USD·kWh−1 and 2.97 USD·kg−1 with a recovery period of 8.05 years, which reveal the economic competitiveness of the STRT system.

This study develops machine-learning models for predicting the solubility of Glibenclamide and the density of supercritical CO₂ under varying temperature and pressure conditions. Three regression techniques-Polynomial Kernel Ridge Regression (PKR), Weighted Least Squares (WLS), and Gradient Boosting Trees (GBT)-were employed, with hyperparameters optimized via the Rain Optimization Algorithm (ROA). PKR delivered the highest solubility-prediction accuracy, achieving an R2 of 0.98689, RMSE of 3.1884 × 10⁻1, MAE of 2.73613 × 10⁻1, and MAPE of 1.33900 × 10⁰. For density prediction, PKR also performed best, with an R2 of 0.98169, RMSE of 2.0935 × 101, MAE of 1.70231 × 101, and MAPE of 2.92063 × 10⁻2. GBT showed competitive performance (R2 = 0.93256 for solubility; 0.91889 for density), while WLS produced moderate accuracy. In comparison with previous studies that modeled Glibenclamide solubility using simpler machine-learning methods, the present work introduces an advanced PKR-ROA framework capable of accurately predicting both solubility and supercritical-fluid density. The proposed approach provides a practical computational tool for optimizing SC-CO₂-based pharmaceutical processing.

Residues of pesticides require efficient and selective sample preparation, due to their existence in trace levels and the complex nature of food matrices. The objective of this study was to use a multivariate experimental design for the determination of multi-residue pesticides in the green coffee beans utilizing supercritical carbon dioxide (sc-CO2) as extraction solvent. In this study, an extraction method based on sc-CO2 as a solvent, at high pressure using Al2O3 as a masking agent for caffeine removal, was developed for the determination of pesticide residues in green coffee beans. A Box-Behnken experimental design was utilized to optimize extraction parameters, including pressure (200-800 bar), temperature (40-70 ℃), and volumes of sc-CO2 (10-40 mL). The optimum extraction conditions were found to be 588 bar, 46 °C, and 40 mL. The method's performance was evaluated by extracting 5 µg g-1 spiked green coffee bean samples, resulting in good linearity (R2 ≥ 0.995); repeatability (3.7-10.3%), and reproducibility (1.6-8.4%). Limit of detection (LODs), Limit of quantification (LOQs), and recoveries were in the ranges 0.02-0.05 µg g-1, 0.08-0.13 µg g-1, and 86-97%, respectively. The developed method could be used as an alternative method for the determination of α-hexachlorohexane (α-HCH), lindane, b-hexachlorohexane (b-HCH), and malathion in green coffee beans. KEY WORDS: sc-CO2, GC-MS, Green coffee bean, Multivariate optimization, Pesticide residues Bull. Chem. Soc. Ethiop. 2026, 40(1), 183-197. DOI: https://dx.doi.org/10.4314/bsce.v40i1.15

Supercritical CO₂ (scCO₂) has a gas-like diffusivity and a liquid-like density, which speeds up transport and allows for tunable termination chemistry during MXene synthesis. This mini review compares scCO₂-assisted routes...

ABSTRACT The recovery of solutes from ionic liquids (ILs) remains a key challenge in the design of green separation processes. In this study, the distribution constants ( K D , SC − C O 2 / IL ) of six halogenated 8-quinolinol derivatives between supercritical carbon dioxide (SC-CO2) and the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][Tf2N]) were determined. The results showed that K D , S C − C O 2 / IL values for all derivatives increased with CO2 density, reflecting enhanced intermolecular interactions. Analysis of the K D , SC − C O 2 / IL dependence on CO2 density, based on the Chrastil model, indicated that the number of solvating CO2 molecules around the derivatives in the SC-CO2 phase remained constant, regardless of whether the co-existing phase was the IL or water. It was also confirmed that derivatives with bulkier substituents exhibited a greater dependence of K D , SC − C O 2 / IL on CO2 density. Regarding the K D , S C − C O 2 / IL sequence, no consistent trend was observed with halogen substitution. This is because increased hydrophobicity enhances solute affinity for both SC-CO2 and IL phases simultaneously, causing these effects to cancel each other out in the biphasic system. To verify this interpretation, values for HQ and 5-Cl-HQ were estimated using existing SC-CO2/water and IL/water data. The estimated values agreed well with experimental results. These findings suggest the feasibility of predictive modeling for solute distribution in SC-CO2/IL systems, contributing to the rational design of sustainable extraction processes.

Thermally super-insulating nanofibrous curdlan aerogels with low shrinkage.

Quantitative investigations on stress corrosion cracking initiation and propagation behavior of 20Cr-25Ni-Nb stainless steel in supercritical carbon dioxide at 650°C