Thin‐film composite membranes incorporated with large‐area graphene oxide sheets and adjustable surface charges

Abstract

In this research, composite membranes were prepared by cross‐linking of poly(vinyl alcohol) (PVA) and glutaraldehyde (GA) on amidoximated ultrafiltration membrane. During this procedure, it was taken advantage of large‐area graphene oxide sheets as graphitic nets in the active layer. These membranes were used to remove an industrial textile dye (Chrysophenine GX) from wastewater. Optimum condition for membrane preparation was 1.5% wt. of PVA, 1.5% wt. of GA, and 0.3% wt. of graphene oxide sheets. Permeation results showed that electrostatic charges on membrane surface have easily converted from positive into negative ones. Contact angle was significantly decreased (63.5° to 28.8°). Final nanofiltration membrane showed lowest fouling rate during removing the industrial direct dye (flux recovery ratio: 96.60%, reversible fouling ratio: 23.82%, and irreversible fouling ratio: 3.39%). Pore size of this membrane was <8 nm, and Chrysophenine GX was eliminated by 98.5% with water permeability of 12.23 L/m2.h.bar.