Membrane Gas Absorption (MGA), a recognized cost-effective technique, demonstrates substantial potential for the efficient capture of carbon dioxide (CO2). Numerous investigations have been dedicated to augmenting membrane hydrophobicity, thereby enhancing membrane stability in the extended course of CO2 capture via MGA. Nevertheless, the applications of CO2 absorption remain limited owing to the relatively low CO2 absorption flux across the membrane. In the present study, our objective is to fabricate a CO2-philic thin film on the membrane surface, thereby significantly improving CO2 absorption efficiency. To assess membrane performance, we subjected two polyvinylidene fluoride (PVDF) membranes, PVDF/EDA and PVDF/GO, to surface coatings of ethylenediamine (EDA) and graphene oxide (GO). In terms of wetting behaviour, the membranes exhibited distinct characteristics. The CO2-philic surface displayed a water contact angle (WCA) of 49.6° ± 2.7, while the superhydrophobic surface exhibited a WCA of 149.8° ± 3.3 and a surface area (SA) of 9.9° ± 3.3. These findings underline the asymmetric wetting properties of the membrane. For MGA performance, the PVDF/EDA/GO membranes, equipped with CO2-philic functional groups, demonstrated remarkable performance improvements. They exhibited a CO2 absorption flux of 0.0040 mol/m²s and an impressive selectivity of 6. These results clearly surpassed the performance of the pristine PVDF membrane, which recorded a selectivity of 3.0, nearly half that of the composite membrane. This study underscores the potential of dual-wetting membranes, characterized by a hydrophilic CO2-philic side and a superhydrophobic surface on the other, as a promising strategy for effective CO2 capture in the context of MGA.

Keywords: Asymmetric wetting; CO2 capture; MGA