Synthesis of a Free-Standing Ternary WO3/CNT/ZnO–Chitosan Composite Photocatalytic Membrane for the Mitigation of Protein Fouling in Membranes

The application of membrane filtration, particularly micro- and ultra-filtration, in food and pharmaceutical industries often faces the issue of protein fouling. In this study, we aimed to fabricate a free-standing ternary tungsten trioxide/carbon nanotube/zinc oxide (WO₃/CNT/ZnO)-chitosan composite photocatalytic membrane via wet processing and infiltration techniques to address the fouling issue. Infiltration with low molecular weight chitosan was found to enhance the mechanical stability of the ternary composite photocatalytic membrane. The ternary composite photocatalytic membrane with a 0.16 g ternary photocatalyst load demonstrated 86% efficiency in the degradation of bovine serum albumin (BSA) under sunlight irradiation for 120 min. A reduction in permeation flux accompanied by an increase in BSA rejection was observed as the loading of the ternary photocatalyst in the ternary composite photocatalytic membrane was increased. This can be associated with the decreased average porosity and mean pore radius. The ternary composite photocatalytic membrane demonstrated reasonably good antifouling behavior with an <i>R_fr</i> of 82% and an <i>R_if</i> of 18%. The antifouling property demonstrated by the ternary composite photocatalytic membrane is important in maintaining the reusability of the membrane.