Integration of microfiltration and visible-light-driven photocatalysis on g-C3N4 nanosheet/reduced graphene oxide membrane for enhanced water treatment

Abstract

A graphitic carbon nitride nanosheet/reduced graphene oxide/cellulose acetate composite photocatalytic membrane (g-C3N4 NS/RGO/CA) was fabricated by assembling a g-C3N4 NS/RGO photocatalyst on the surface of commercial CA membrane. Owing to the attractive photocatalytic efficiency of g-C3N4 NS under visible light irradiation and photogenerated charge separation resulting from the unique hetero-structure between g-C3N4 NS and RGO, g-C3N4 NS/RGO/CA composite photocatalytic membranes exhibited superior performance in water treatment under visible light irradiation. The removal efficiency of Rhodamine B by the integrated process of filtration and visible light driven photocatalysis was four times that of membrane filtration alone. The integrated process also displayed efficient inactivation of Escherichia coli at three orders of magnitude higher than that of filtration alone. The permeate flux for the integrated process was 3.7 times that of filtration alone, suggesting its good anti-fouling property under visible light irradiation. The integrated system was employed to treat surface water and evaluate its performance in real water treatment. The integrated process showed much better efficiencies for the removal of CODMn, TOC, UV254, and bacteria from surface water than those of membrane filtration alone. This work gives insight to the effective application of solar energy for the improvement of membrane separation in water treatment.