Owing to rising environmental awareness, the textile dyeing and finishing industry faces increasing pressure to reduce water consumption and chemical wastewater generation of conventional aqueous dyeing processes. Supercritical carbon dioxide (scCO₂) dyeing, a water-free dyeing method, conserves water resources and prevents water pollution. Polypropylene (PP) fabrics are promising eco-friendly textile materials owing to their simple structure, low carbon emissions, and less weight. High crystallinity and lack of polar functional groups in their molecular structure makes them difficult to dye. PP fibers are commonly colored via mass pigmentation. However, limited flexibility in masterbatch formulations restricts color mixing and shade modification. In this study, a series of styrene–maleic anhydride (SMA) copolymers grafted with long-chain alkyl amines were synthesized and used as dispersing agents in scCO₂ dyeing systems to enhance the disperse dye uptake of PP fibers. When applied to a disperse yellow dye (JY) and blue dye (JB), the SMA dispersants significantly improved dyeing performance under scCO₂ conditions. For a JY with an SMA dispersant, the Kubelka–Munk function (K/S) value increased by approximately 27.7%, whereas levelness (ΔE*) decreased by 47.1%. For a JB with an SMA dispersant, the K/S value increased by 39.7%, and ΔE* decreased by 42.6%. In a mixed-dye system, the SMA dispersant addition resulted in a 39.5% increase in K/S and 20.5% reduction in ΔE*. This study demonstrates the feasibility of using SMA–alkylamine polymeric dispersants to improve the dyeing performance and surface hydrophobicity of PP fabrics under water-free scCO₂ dyeing conditions without the use of fluorinated additives.
Electrochemical CO2 reduction (CO2RR) can convert carbon dioxide into carbon monoxide, formate, and multicarbon fuels, but its selectivity, energy efficiency, and stability remain limited by sluggish interfacial kinetics, competing hydrogen evolution, and mass-transport gradients. Magnetic regulation has recently emerged as a non-contact strategy that can act through several physically distinct routes. This mini review therefore separates four mechanistic routes that have been proposed or demonstrated and that are often conflated: radical-pair singlet–triplet interconversion, field-induced polarization of active sites or magnetic domains, Lorentz-force-driven magnetohydrodynamic transport, and field-free spin control based on chirality-induced spin selectivity, topological surface states, and coordination-controlled spin states. Reported catalyst families are compared by material class, target product, magnetic-field configuration, and performance outcome. Representative systems include Sn and Bi catalysts for formate, Ni-based catalysts for CO, and Cu-based interfaces, radical-modified metal–organic frameworks, and chiral Ag for C2+ products. Particular attention is paid to controls needed to distinguish genuine spin effects from transport, heating, and geometric artifacts. The review closes with design rules for mechanism-matched field orientation, field-free spin control, operando validation, and a net-energy and techno-economic framework for flow electrolyzers. Reported fields span from tens of millitesla to 2 T, with substantial gains in C2+ and CO selectivity under selected conditions. However, to our knowledge, reported energy savings remain confined to cell-level analyses because auxiliary magnet, cooling, and pumping loads have not been fully measured. Overall, this work provides a mechanistic framework for rationally exploiting magnetic and spin effects in CO2RR and guides the design of more selective, energy-efficient, and stable electrocatalytic systems.
In calcium looping, captured CO2 is fixed as solid CaCO3, whose decomposition typically requires temperatures around 700 °C. Lowering this decomposition temperature is a key requirement both for utilizing the captured carbon and for regenerating the CaO-based sorbent. This study investigates CH4 generation from solid-phase calcium carbonate (CaCO3) using Ni-supported composites under a hydrogen atmosphere and examines the effect of lanthanum (La) addition. Gas chromatography confirmed CH4 formation at 500 °C without external CO2 supply, while CH4 was not detected from bare CaCO3, suggesting that Ni plays a key role in hydrogen activation. La addition increased CH4 yield and prolonged the reaction duration. XRD, XPS, and TGA analyses indicated that CaCO3 decomposition occurs preferentially at the outermost surface region and is associated with atomic hydrogen supplied from Ni surfaces. Similar decomposition of CaCO3 with a range of 100 nm was observed away from Ni film / CaCO3 interfaces fabricated by a sputter deposition of Ni on a CaCO3 (100) substrate. XPS results showed that La species were ultimately converted to La(OH)3 after the reaction, suggesting that La might have collected CO2 from the surrounding CaCO3 and acted as a local reaction site during this transformation. La addition also suggested to suppress carbon deposition on Ni surfaces. These results indicate that CH4 generation from solid CaCO3 is confined to the region reached by atomic hydrogen supplied from Ni, and that La addition extends this region by providing local sites for CO2 transfer.
Cupriavidus necator'stungsten-dependent NAD(+)-reducing formate dehydrogenase (CnFDW) has strong potential as a cofactor-recycling biocatalyst, as it remains active under ambient air (similar to 21% O-2) and elevated O(2)levels (up to 50%). Using formate as a clean reductant,CnFDW enables efficient NADH regeneration for diverse oxidoreductases and oxygenases under aerobic conditions, achieving complete conversion of representative substrates within 8 h and retaining high product yields (92-87%) upon a 10-fold increase in reaction volume and higher substrate concentrations. In reverse reaction, coupling ofCnFDW to the O-2-tolerant NAD(+)-reducing hydrogenase ofC. necator(CnSH) enables H-2-driven CO(2)reduction to formate. In anaerobic conditions, concentrations of up to 64 mM formate were achieved, when using methyl viologen instead of NAD(+)/H as electron mediator. Overall, these results establishCnFDW as an O(2)tolerant biocatalyst for both, aerobic cofactor recycling and sustainable H-2-driven CO(2)valorisation to formate.
Biomass gasification is a promising thermochemical conversion technology for producing renewable synthesis gas; however, the significant amount of generated CO2 during the process reduces gas quality and carbon utilization efficiency. Integrating carbon capture with thermochemical conversion offers an opportunity to improve both process sustainability and resource efficiency. In this study, a closed-loop CO2 capture and utilization system was developed by coupling post-situ adsorption with biomass gasification. Maize biomass was thermally pretreated at 200–500°C before gasification at 800°C and 900°C. The produced CO2 was captured using cattle manure derived biochar, while the desorption was made at 80°C where the gases were subsequently recycled into the gasification process. Thermal pretreatment and CO2 reutilization significantly enhanced gasification performance, with the highest syngas yield. The proposed approach demonstrates that captured CO2 can effectively be recycled as a gasification agent, improving synthesis gas quality while promoting carbon circularity and reducing process related CO2 emissions.
