Graphene oxide-chitosan coated PVDF adsorptive microfiltration membrane: Enhancing dye removal and antifouling properties.

This study investigates graphene oxide (GO) modified poly(vinylidene fluoride) (PVDF) membranes focusing on their dye rejection efficiency and their antifouling properties against bovine serum albumin (BSA). These membranes were prepared by modifying commercial PVDF membrane with a thin layer of GO nanosheets and chitosan (CS) using vacuum filtration. The synergistic physicochemical properties of the GO-CS/PVDF membranes were analyzed by XRD, FTIR, Raman, and XPS spectroscopy. The surface morphologies were observed by SEM and AFM microscopy, and WCA measurements. The deposition of GO and CS in the presence of citric acid resulted in a decrease in pore size and an increase in hydrophilicity. Modified membranes showed enhanced rejection of RB and MB, with rates increasing from 13.0 to 96.0 % and 28.3 to 69.1 %, respectively. Antifouling studies using BSA on selected membranes outperformed pristine membranes, which had higher irreversible fouling due to pore blockage. GO-CS/PVDF membranes exhibited higher flux recovery and lower irreversible fouling due to increased hydrophilicity, which prevents tight cake layer formation. Minimal detachment of the GO-CS layer during the long-term stability test is confirmed by minor fluctuations in dye flux and rejection. In summary, enhancing PVDF membranes with GO and CS augments dye rejection rates and bolsters antifouling properties.