Functionalization of reverse osmosis membrane with graphene oxide to reduce both membrane scaling and biofouling

Abstract

In this paper, commercially available graphene oxide (GO) was used as nanomaterials to modify polyamide reverse osmosis (RO) membrane surface. After functionalization, the membrane surface properties were improved as the water contact angle was reduced from 41.7 � 4.5? to 26.9 � 0.9? demonstrating improvement in hydrophilic properties besides decreasing membrane surface roughness. Membrane scaling tests were done in the presence of CaSO4 solution at 20 mM concentration as feedwater showed that the modified membranes (GO@RO) had superior anti-scaling properties. Results indicated that the permeate flux was reduced by only 15% at the end of the scaling experiment as opposed to the bared RO membrane which faced up to 22% decline in flux. The results of scanning electron microscopy, Fourier transform infrared, and X-ray diffraction confirmed that the bared RO membrane was extensively scaled by the CaSO4 precipitates. The results of antibacterial tests showed that GO functionalization caused an inhibition of bacterial growth by 81.7% as compared to the unmodified RO membrane. Moreover, experiments were also performed to investigate microbially induced calcium sulfate precipitation on membranes. Overall, it was found that GO functionalization not only reduces biofouling but can also inhibit mineral scaling and microbially induced mineral formation.