Emulsification and foaming frequently occur during crude oil production, transportation and separation. However, the mechanisms underlying the temperature-dependent differences in foaming behavior between crude oil and its emulsion remain insufficiently understood. This study examines these differences through measurements of viscosity-temperature behavior, wax precipitation, net CO2 release, interfacial tension, interfacial dilational modulus, and foam drainage. Temperature markedly affects the foaming behavior of both fluids. At temperatures of 30 °C and below, the emulsion exhibits greater foamability than crude oil, whereas the difference is small at 35 °C and above. This behavior is associated with the coupled effects of bulk rheology and interfacial properties. Below the wax appearance temperature, dispersed droplets and networks of precipitated wax crystals increase the apparent viscosity of the emulsion. The oil-gas interface in the emulsion exhibits lower viscoelasticity than that in crude oil, which may be associated with the adsorption of surface-active components at oil-water interfaces. Higher viscosity favors foam persistence, whereas the lower interfacial dilational modulus may counteract this effect. The lower CO2-liquid interfacial tension of the emulsion also favors bubble formation. In contrast, its lower net CO2 release does not explain its greater foamability. The observed differences are therefore interpreted in terms of the combined effects of viscosity, interfacial tension, and net CO2 release. These findings provide insight into the combined contributions of bulk rheology, interfacial properties, and CO₂ release dynamics, with implications for foam control, oil-gas separation, and flow assurance.
Mesoporous silica is an attractive carrier for poorly water-soluble drugs, and supercritical fluid deposition (SCFD) with CO₂ loads them without organic solvents. The loading passes through a maximum with impregnation pressure, commonly attributed to the opposing effects of CO₂ density on drug solubility and competitive CO₂ adsorption. Because solubility is a property of the drug–CO₂ pair alone, the pressure of the maximum might be assumed transferable between carriers, but pressure-resolved data for ordered mesoporous silicas exist only for one-dimensional channels. Ibuprofen and ketoprofen were impregnated into MCM-48, with a three-dimensional bicontinuous pore network, at 333 K and 8–21 MPa; loadings were measured by thermogravimetry and pore structures by nitrogen adsorption. Among the pressures examined, the loading of both drugs was highest at 18 MPa, versus 15 MPa in published SBA-15 data. The ketoprofen data support the shift: loading fell by 33% from 15 to 17 MPa on SBA-15 but rose by 20% from 15 to 18 MPa on MCM-48; for ibuprofen, the differences near the maximum are within the reproducibility. As the silicas also differ in surface area and pore size, its cause was not isolated. The occupied-volume ratio R, the pore volume made inaccessible to nitrogen per volume of drug loaded, was 0.8–1.1 for ibuprofen up to 18 MPa and 2.2–3.2 for ketoprofen, which we interpret as nearly volumetric filling by ibuprofen and obstruction of pore entrances by ketoprofen. The pressure of maximum loading thus depends on the carrier and should be verified for each drug–carrier system.
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.
