This paper reports a series of liquid materials suitable for use as high-performance separation membranes in direct air capture. Upon mixing two ionic liquids (ILs), namely N-(2-aminoethyl)ethanolamine-based IL ([AEEA][X]) and 1-ethyl-3-methylimidazolium acetate ([emim][AcO]), the resulting mixtures with a specific range of their composition showed higher CO2 absorption rates, larger CO2 solubilities, and lower absolute enthalpies of CO2 absorption compared to those of single ILs. NMR spectroscopy of the IL mixture after exposure to 13CO2 allowed elucidation of the chemisorbed species, wherein [AEEA][X] reacts with CO2 to form CO2–[AEEA]+ complexes stabilized by hydrogen bonding with acetate anions. Supported IL membranes composed of [AEEA][X]/[emim][AcO] mixtures were then fabricated, and the membrane with a suitable mixing ratio showed a CO2 permeability of 25,983 Barrer and a CO2/N2 selectivity of 10,059 at 313.2 K and an applied CO2 partial pressure of 40 Pa without water vapor. These values are higher than those reported for known facilitated transport membranes.

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To utilize a super-hydrophobic tetradecane-adsorbed marshmallow-like gel as a phase-change material (PCM) as a carrier for latent heat transportation by mixing the gel particles with sodium carboxymethyl cellulose (CMC) solution, the dispersion characteristics and flow characteristics of a marshmallow-like gel slurry were investigated. To investigate the dispersion characteristics of the slurry, visual observation of the slurry under static conditions was performed while varying the concentration of CMC, and the apparent dispersion fraction was determined for quantifying dispersion characteristics. The apparent dispersion fraction stabilized within 2 h. At CMC concentrations of < 0.4, 0.6-2, and > 3 wt%, the apparent dispersion fraction increased, remained constant, and reached the complete dispersion state, respectively. At several concentrations, the viscosity of the liquid layer of the gel slurries was lower than that of the pure solution, coinciding with the range where the apparent dispersion fraction increased. Therefore, it was found that the adsorption of CMC onto the surface of marshmallow-like gel affects the dispersion characteristics of marshmallow-like gel slurry. To investigate flow characteristics, friction factor of CMC solution and marshmallow-like gel slurry against Reynolds number was measured. From the results, it was confirmed that the shear-thinning of the CMC solution affected the flow characteristics.

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