Polymeric reverse osmosis membranes have been employed to separate lipid mixtures using supercritical carbon dioxide (SC-CO2), where the operating conditions and solute-solvent-membrane interactions affect the separation. To understand these interactions, the wetting phenomena was studied by determining the apparent contact angles (CAapp) of oleic acid (OA) and triolein (TO) in air (22 °C/1.01 bar) and SC-CO2 (40 °C/120 bar) on a commercial SG membrane over 1 s. Under atmospheric conditions, the CAapp of OA (49.74° ± 0.64°) and TO (56.80° ± 1.05°) at 0 s showed a difference, indicating stronger affinity of the membrane for OA. The CAapp of OA (37.33° ± 0.27°) and TO (53.92° ± 0.86°) decreased under SC-CO2. This decrease was greater for OA due to its higher solubility and lower interfacial tension in SC-CO2 than TO. The findings indicate that SC-CO2 enhances the wetting behavior...

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