Ultrathin graphene oxide nanosheet membranes with various d-spacing assembled using the pressure-assisted filtration method for removing natural organic matter

Abstract

The peculiar two-dimensional structure and chemical properties of GO offer a facile stacking method for preparing this new type of membrane. In this study, GO membranes were made using the pressure-assisted filtration method, which was cross-linked by three diamine monomers on a polyethersulfone (PES) support. The prepared GO membranes had a well stacked layer structure that was formed by nanosheets and were stable because they were covalently bonded by cross-linking. The effects of various diamine monomers on the synthesized membrane were analyzed using several characterization methods, including Fourier transform infrared spectroscopy (FTIR), dynamic contact angle (CA) measurements, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The performance of the GO membranes for removing natural organic matter (NOM) was investigated in detail. The permeate water was analyzed for dissolved organic carbon (DOC), ultraviolet absorbance (UV 254), molecular weight distribution (MWD) and fluorescence excitation-emission matrices (EEMs). The results showed that C-N covalent bonds formed between the GO and diamine and effectively suppressed the interlayer spacing and stretching, which resulted in the best ethylenediamine performance. Overall, the ultrathin GO composite membrane not only effectively removed various contaminants from the NOM, but also qualified the water flux and fouling resistance performance.