Economic feasibility and profitability analysis of scCO2-based gold recovery process from waste printed circuit boards.

Abstract The tritium breeding capacity of fusion blankets is a critical factor in achieving tritium self-sufficiency in fusion reactors. Current designs for tritium production in blankets are based on neutronics simulations, whose accuracy requires experimental validation. This study focuses on the experimental validation of the neutronic design reliability of the supercritical CO 2 -cooled lithium-lead (COOL) blanket developed for the China fusion engineering test reactor (CFETR). For this purpose, an experimental mock-up was designed and fabricated to replicate the key neutronics characteristics of COOL blanket. The mock-up was irradiated using D–T neutron generator and validated using multiple techniques: tritium production rate (TPR) online monitoring with a miniature back-to-back lithium glass scintillator detector, TPR integral measurement using Li 2 CO 3 pellets analyzed by liquid scintillation counting (LSC), and neutron flux measurement with activation foils (Au, Zr). To enhance accuracy, corrections were applied for lithium-lead (PbLi) segregation based on element analysis and for neutron source intensity based on in-situ depth profiling of tritium in the tritide target. The results show excellent agreement between experiments and simulations, with calculation-to-experimental (C/E) value ranging from 0.96 to 1.11 for TPR measured by lithium-glass scintillator detectors, 0.90–1.09 for TPR by Li 2 CO 3 pellets, and 0.84–1.13 for reaction rates measured by activation foils.

Photocatalytic reduction of carbon dioxide (CO2) into high-value multicarbon products, such as ethylene (C2H4), remains a significant challenge due to the difficult C-C coupling process. Potassium poly(heptazine imide) (K-PHI) is a promising photocatalyst, yet efficiently exchanging its interlayer cations to tune catalytic selectivity without causing structural degradation is difficult. Herein, an efficient and green supercritical CO2 (SC CO2) assisted ion-exchange strategy was developed to successfully prepare a series of mono-/di-/trivalent cation-doped M-PHI photocatalysts (M = H+, Na+, Sr+, Ca2+, Co2+, Fe3+). Systematic characterizations confirmed that the SC-CO2 treatment successfully achieved in-depth cation substitution without destroying the intrinsic heptazine framework, effectively regulating the interlayer structure and significantly optimizing the photoelectrochemical charge separation. Among the prepared samples, H-PHI exhibited the optimal photocatalytic CO2 reduction performance with an outstanding selectivity toward C2H4 generation. Under simulated sunlight irradiation for 3 h, the yields of CO, CH4, and C2H4 C2H4 C2H4 reached 3564.87, 807.32, and 40.00 μmol·g-1, respectively, significantly outperforming pristine K-PHI and other metal-doped samples. Crucially, isotope-tracing experiments utilizing a SC CO2-DCl treatment detected deuterated CH4 and C2H4 products, providing direct evidence that the hydrogen in the carbon products originates from the introduced protons, thereby elucidating the precise reaction pathway for C-C coupling. This study provides a green and efficient supercritical CO2 ion exchange strategy for the cation engineering of crystalline carbon nitride, and also offers new ideas and methods for designing high-activity photocatalysts for photocatalytic CO2 reduction.

Early-Stage Recovery of Lithium from Lithium-Ion Battery Black Mass in Pilot Scale Using Supercritical CO ₂

Abstract This review presents a comprehensive and comparative analysis of four prominent bottoming cycles: the Steam Rankine Cycle (SRC), the Supercritical CO₂ Brayton Cycle (s‐CO₂), the inverse Brayton cycle (IBC), and the Air Bottoming Cycle (ABC) integrated with proton exchange membrane (PEM) electrolyzers for hydrogen production. The study evaluates each cycle through a multi‐criteria 4E framework (energy, exergy, economic, and environmental performance). The SRC system emerges as the most promising, achieving an exergy efficiency of 21.93% and a hydrogen production efficiency of approximately 57.4%. In comparison, the IBC lags with an exergy efficiency of 13.72% due to higher irreversibilities. Hybrid configurations employing thermoelectric generators (TEGs) further enhance low‐grade heat recovery, adding up to 1.2–2.4% to the overall system efficiency. The exergoeconomic analysis reveals a cost rate of $32.8/GJ for SRC‐based hydrogen systems compared to $25.58/GJ for IBC, suggesting a trade‐off between cost and performance. The integration of bottoming cycles with PEM electrolyzers presents a viable route to reduce fossil fuel dependency and greenhouse gas emissions, potentially cutting lifecycle CO₂ emissions by 12–20%. This review highlights technology synergies crucial for transitioning toward a hydrogen‐enabled circular energy economy.

Direct-fired supercritical CO2 cycles are one of the promising approaches to eliminate CO2 emissions in the power energy sector, while maintaining high efficiency and the ability to burn fossil fuels. One of the key elements of such cycles is the combustor, in which natural gas is burned in an O2/CO2 environment at supercritical pressure. Oxy-fuel CO2-diluted combustion differs significantly from traditional air-fuel combustion, which creates the need to adapt existing numerical modeling techniques. Experimental data are required to verify numerical methods, but present experimental studies are fragmented and non-formalized. This paper presents the results of an experimental test of the 15 kW oxy-fuel burner device in a tunnel gas furnace at atmospheric pressure. Experimental tests were carried out with oxygen-fuel ratios (α) of 1, 1.45, and 1.75 in the range of CO2 mass fractions in the oxidizer (γ) from 0 to 0.9. An experimental temperature profile is obtained, the adiabatic combustion temperature is calculated, and the boundaries of stable combustion are determined. Based on the experimental results, the main similarity criteria of combustion were calculated, and it was shown that by changing the composition of the model mixture, it is possible to reduce the discrepancy of the similarity criteria between the model and full-scale oxy-fuel combustors.

Tissue scaffolds are one of the main components of the tissue engineering triad, playing a vital role in tissue engineering. However, their production procedures heavily rely on solvent-intensive and energy-demanding methods. This raises serious questions about industrial-scale manufacturability, residual solvent toxicity to living health, and sustainability for nature and the environment. Therefore, the main aim of this study is to identify robust scaffolds that provide a suitable microenvironment for resident cells and promote tissue regeneration, while reducing waste through environmentally friendly production methods. In this context, the scalable and ecologically friendly production methods emerge as necessary alternatives as biodegradable polymer scaffolds are used in more therapeutic settings. Clinically applicable and green synthesis-based supercritical carbon dioxide (scCO2) technologies, melt electrowriting (MEW), and solvent-free processing techniques are the main topics of this study for a critical analysis of biodegradable polymer scaffold production techniques. Scaffold structure-property correlations, polymer selection and interactions, production procedures, the benefits and drawbacks of existing fabrication technologies, and sustainability issues are discussed in detail. It aims to contribute a novel perspective and approach to literature by presenting and comparing production-oriented approaches as sustainable and green methods. The challenges in the development of biodegradable tissue scaffolds, along with the significance of green manufacturing techniques, are also revealed. The approach is designed to connect processing factors to scaffold features in addition to evaluating current technologies. This review tries to offer a framework for producing biodegradable polymer scaffolds in a sustainable and clinically implementable context.

We present a systems-level dynamic analysis and control strategy for a recuperated supercritical CO2 Brayton-cycle pumped thermal energy storage system designed to simultaneously deliver grid energy-storage services and multitemperature heat input to industrial sites. A control-oriented dynamic model is developed in MATLAB/Simulink; turbomachinery submodels and finite-volume heat exchanger models capture the thermodynamic transient behavior. Accordingly, control functions are designed and assessed against four objectives: antisurge control for safe turbomachinery operation, cycle power set point tracking for grid services, inventory control to enable operating-point transitions, and coordinated startup/shutdown sequencing. Simulations demonstrate robust transient performance, with power-tracking settling times of 15-45s. Inventory control enables reliable switching between thermodynamic cycle configurations for multitemperature heat pumping, stabilizing pressures within 48 s and temperatures within 73 s. Together, these results provide ramp-rate constraints relevant to operational scheduling and support the feasibility of PTES as a bridge between variable renewable electricity and industrial thermal demand.

ABSTRACT Thermoplastic polyamide 12 elastomer (TPAE12) offers excellent thermal stability, mechanical tunability, and chemical resistance, making it promising for elastic foams. However, its low melt strength often leads to pore collapse and poor elasticity. Here, TPAE12 (PEBA) was blended with cost‐effective TPAE6 and foamed using supercritical CO 2 to produce lightweight composite foams. Adding just 10 wt% TPAE6 enhanced melt strength, inhibited pore coalescence, and promoted homogeneous nucleation by creating zigzag gas diffusion paths through microphase separation. Therefore, the expansion coefficient of the composite foam increased by 31% compared to pure PEBA, with a density as low as 0.071 g/cm 3 , which is comparable to the density level of commercial PEBA bead foams. Notably, this ultra‐low density was achieved by adding only 10 wt% of TPAE6, significantly reducing the raw material cost of the foam system. The study also found that smaller bubble sizes correspond to higher compression stability and resilience, whereas larger bubbles weaken these performance metrics. Compared with pure PEBA foam, this composite foam presented a uniform closed‐cell structure without cell fusion/collapse. Therefore, these findings demonstrate that super‐elastic PEBA/TPAE6 composite foams—with their lightweight, highly elastic, and structurally tunable character—hold strong promise for advanced footwear material applications.

Enhanced geothermal systems (EGS) are a key technology for developing deep geothermal resources, yet they face significant challenges in constructing efficient thermal reservoirs within high-stress, high-strength, and low-permeability crystalline rock formations. Traditional hydraulic fracturing (HF) techniques encounter deep challenges in these environments, including excessively high fracturing pressures, limited fracture network patterns, and the risk of induced seismicity. This paper reviews the multi-scale thermal-mechanical mechanisms, fracture evolution patterns, and control strategies associated with thermal stimulation and permeability enhancement in the modification of deep geothermal reservoirs. Research indicates that thermally induced fracturing triggers intergranular and transgranular cracks at the microscopic scale due to mineral thermal expansion mismatches, which macroscopically manifests as nonlinear degradation of rock strength and modulus. The redistribution of the thermal elastic stress field significantly lowers the breakdown pressure, while matrix thermal contraction increases fracture aperture, leading to an exponential enhancement of permeability following a cubic law. However, the high confining pressure constraints, true triaxial stress anisotropy, and thermal short-circuiting risks present substantial suppression and challenges to the effectiveness of thermal stimulation in deep in situ environments. Different fracturing media, such as water, liquid nitrogen (LN2), and supercritical CO2, exhibit varying advantages in thermal stimulation efficiency due to their unique thermal-flow characteristics. Future research should focus on the thermal-mechanical coupling mechanisms under true triaxial stress conditions, and develop intelligent control strategies for permeability enhancement and thermal short-circuiting risk mitigation. This study synthesizes existing analyses and proposes potential engineering strategies for stimulating deep EGS reservoirs, offering significant strategic value for the development of geothermal energy as a baseload renewable resource.

Synthesis of Silsesquioxane Derivatives via Hydrosilylation of Alkenes and Alkynes Catalyzed by Pt/XAD-4 in Supercritical CO ₂

Abstract: The rising global emphasis on sustainability has redefined the priorities in natural product research, necessitating a shift toward eco-conscious sourcing and extraction methodologies. This review distinctly underscores the strategic convergence of sustainable sourcing and green extraction as not merely environmental imperatives but also as drivers of innovation, ethical integrity, and economic resilience. Unlike prior literature that often isolates technological advancement from socio-environmental accountability, this work presents a holistic narrative, evaluating how circular economic frameworks, policy mechanisms like the Nagoya Protocol, and digital traceability collectively enable transparent, equitable, and ecologically sound natural product supply chains. We examine successful real-world integrations of green technologies such as supercritical CO₂ and pressurized hot water extraction in the pharmaceutical and cosmetics sectors, highlighting both scalability and functional efficacy. This synthesis is uniquely positioned to bridge laboratory innovation with industrial feasibility by examining lifecycle impacts, bioeconomy benefits, and regulatory gaps. Importantly, we spotlight overlooked challenges such as restricted access to sustainably cultivated biomaterials, toxicological ambiguities of novel green solvents, and inequitable benefit-sharing with indigenous communities. What sets this review apart is its emphasis on the interconnectedness of sustainability, policy, and innovation, which is essential for redefining the future of natural product development. By incorporating perspectives from omics-based resource optimization, synthetic biology, and biotechnological cultivation, this paper advocates for a paradigm shift that aligns green science with social justice and market viability.

Poly(lactic acid) (PLA) devices can be functionalized with plant-derived bioactives to introduce antioxidant activity while maintaining manufacturability and cytocompatibility. Here, a polyphenol-rich mango leaf extract (MLE) was obtained by enhanced solvent extraction and incorporated into PLA using supercritical carbon dioxide-assisted impregnation. Two manufacturing sequences were compared: impregnation after three-dimensional (3D) printing of discs and impregnation of filaments prior to printing. Extract yield and radical scavenging capacity were quantified, and impregnation efficiency was assessed as a function of pressure and temperature. Biological performance was evaluated using adipose tissue-derived endothelial colony-forming cells (ECFCs) and adipose tissue-derived mesenchymal stromal cells (MSCs), cultured separately and in co-culture on functionalized substrates. Impregnation after printing provided higher and more reproducible loading while preserving disc geometry, whereas impregnation before printing promoted swelling and printing-associated deformation that compromised structural fidelity. Cell-based analyses supported improved adhesion, spatial distribution, and proliferative status on discs produced by impregnation after printing under low-temperature and high-pressure conditions, without evidence of selective loss of either population in co-culture by flow cytometry. These results support post-print supercritical impregnation as a robust route to generate antioxidant, cell-supportive PLA scaffolds from agricultural by-products with potential relevance for vascular-oriented biomedical applications.

Supercritical CO2 (S-CO2) extraction is one of the most employed techniques for the extraction of bioactive compounds for its safety, effectiveness, cost-efficiency, and good environmental compliance. Smyrnium olusatrum L. (Apiaceae) is an aromatic plant of great interest due to its potential applications in pharmaceutical, agrochemical, and oleochemical fields. Its bioactivity is caused by furanosesquiterpenes, mainly represented by isofuranodiene (IFD). The extraction of this compound is usually achieved through Soxhlet or hydrodistillation. However, the latter usually leads to the thermal Cope rearrangement of IFD into its isomer curzerene, resulting in low recovery. This study reported for the first time the optimization of S-CO2 extraction of IFD from S. olusatrum schizocarps. Pressure (MPa), extraction time (min), and static mode (%) were varied while the temperature was maintained at 45 °C to avoid IFD thermal degradation. The optimized process (50 MPa, 60 min, 25% static mode) provided an extraction yield and an IFD recovery of 8.50 and 0.94% and avoided the thermal degradation of the compound. This study demonstrated that S-CO2 extraction is a valuable alternative to conventional hydrodistillation (extraction yield and IFD recovery of 2.64 and 0.77%) and Soxhlet (extraction yield and IFD recovery of 9.49 and 0.85%) to recover IFD from S. olusatrum.

This study evaluated olive leaves from three cultivars (Hojiblanca, Picual, and Arbequina) and olive pomace as complementary sources of bioactive compounds, comparing ultrasound-assisted extraction using organic solvents (UAE) with supercritical CO2 extraction (SFE). The aim was to determine how the plant matrix and extraction method influence phytochemical composition and functional properties, including antioxidant and antimicrobial activity. The results showed that both factors strongly affected extract composition and bioactivity. UAE favored the recovery of phenolic compounds associated with antioxidant activity, particularly in leaf extracts, while SFE promoted a distinct compositional profile enriched in flavonoids and lipophilic constituents, especially in olive pomace. Multivariate analysis confirmed a clear differentiation between matrices and extraction methods. Leaf extracts from Picual and Arbequina were mainly associated with phenolic compounds linked to antioxidant activity, including luteolin, ethyl vanillin, tyrosol, and isorhamnetin-3-O-glucoside. In contrast, olive pomace extracts were more strongly associated with flavonoids and lipophilic metabolites, such as triterpenes (oleanolic, maslinic, and ursolic acids) and lipid derivatives (oleic acid and lauric isopropanolamide). These compositional differences were reflected in biological activity: UAE extracts showed higher antioxidant activity, whereas SFE extracts, enriched in lipophilic and triterpenic compounds, exhibited stronger antimicrobial effects against Pseudomonas savastanoi and Hanseniaspora sp. Overall, these findings demonstrate that extraction-driven selectivity enables the production of olive-derived extracts with targeted functionalities, with UAE favoring antioxidant-oriented extracts and SFE promoting extracts enriched in lipophilic compounds with antimicrobial potential, particularly from olive pomace.

Determination of paclitaxel anticancer drug solubility in supercritical CO2: Thermodynamics modeling and machine learning approach

Data-driven modeling of wax solubility in supercritical carbon dioxide and ethane systems

Functional lightweight polyethylene terephthalate foamed beads from post-consumer bottles using extrusion process assisted by supercritical carbon dioxide

Heat extraction performance of supercritical carbon dioxide flow in rough fractured rock.

Voltage-free fabrication of high-performance porous polypropylene piezoelectrets via in-situ triboelectrification during constrained supercritical carbon dioxide foaming