Efficient removal of dyes and proteins by nitrogen-doped porous graphene blended polyethersulfone nanocomposite membranes

Abstract

Nitrogen-doped porous graphene oxide (N-PGO) was synthesized, characterized, and applied as a hydrophilic nanomaterial in fabrication of polyethersulfone (PES) membrane for Reactive Red 195 dye and bovine serum albumin (BSA) protein separation. The N-PGO nanosheets not merely showed a good adhesion towards polymers, but simultaneously promoted hydrogen bonding action. Therefore, high-efficiency permeation passageway in the separation layer of membranes was attained. X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDX) and Fourier transform infra-red spectroscopy (FTIR) analyses approved nitrogen doping, which increased hydrophilicity and hydrogen bonding ability of PGO in water filtration. The pure water permeation of nanocomposite membranes could reach as high as 190 L m−2 h−1 at 3 bar. A dye rejection efficiency higher than 92% and BSA rejection higher than 95% were accordingly obtained. Atomic force microscopy (AFM) images approved formation of a rough surface that was decreased by addition of low amounts of the PGO. SEM images provided from the surface also confirmed enlarged pore size and increased porosity. Antifouling properties were investigated by BSA filtration, and results showed that the flux recovery ratio of the N-PGO membrane was improved. Overall, the N-PGO hybrid membranes exhibited potential for application in separation of typical proteins and dyes with good antifouling properties.