Effect graphene oxide nanostructure/tannic acid on mixed polymeric substrate-surface modified RO membranes

In this work, polyamide (PA) layer of (TFC) thin-film composite in reverse osmosis (RO) membranes are compared to facile cost-effective lower rejection RO- blend membranes using graphene oxide. Polyvinyl alcohol (PVA) is cross-linked with glutaraldehyde hydrogel and thereby showing the effect of a fixed concentration of graphene oxide (GO) at different surface modification stages. Surface grafting using methacrylic acid is performed to govern the role of the protective layer on the efficiency of the covered TFC layer as membranes performance regarding salt rejection and permeability. GO concentration of 0.25 wt% in PVA solution shows a maximum % rejection reaching 70 for 3PG and the highest permeate flux for 1PG is 45.52 LMH. While the TFC membranes T and TG have shown higher rejection percentages to reach 88.31% for 3TG of and the highest permeate flux is 30.7 LMH for 1TG and decreases to reach 24.56 LMH for 3TG. Different membrane characterizations are fulfilled through surface morphology, wettability, BET area, and adsorptive fouling. Optimized ratios for tannic acid, ZnO-nanostructure, and graphene oxide with the mixed polymeric substrate are reached. The effect of graphene oxide in the surface grafting layer over blend and TFC membranes are presented.