Synthesis and Characterisation of Polyvinylpyrrolidone Based Graphene Oxide Composite Membrane

Numerous industries produce oily wastewater, significantly impacting human health and the environment. Effective treatment technologies are essential to manage and mitigate the impacts of oily wastewater discharge. Forward osmosis (FO) process is a promising membrane process for oily wastewater treatment. It is less prone to fouling and require lower energy inputs compared to traditional pressure-driven processes. Polymeric membranes have shown promising applications in FO process. However, their intrinsic hydrophobicity leads to severe fouling, which significantly deteriorates their separation performance. To overcome these challenges, surface modifications are essential for improving the performance of polymeric membranes. This work focuses on the development of a thin film nanocomposite (TFN) membrane that combines polysulfone (PSf) and polyvinylpyrrolidone (PVP) with graphene oxide (GO) for the purification of oily wastewater. The characterisation of nanoparticles (NPs) is undertaken by using zeta potential (ZP) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). ZP results of nanoparticles, show that the PVP-modified GO NPs has higher value of -41 mV than GO NPs, confirming greater dispersibility. The disappearance of the peak at 1732 cm−1 in the ATR-FTIR spectra of PVP-GO nanoparticles, compared to GO, indicates that some of the oxygen-containing functional groups of GO have been modified during the preparation of PVP-GO, and new chemical bonds have formed. The resultant membrane properties are characterised using several analytical tools, including ATR-FTIR, field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The peak at around 3382 cm-1 and the increasing intensity at 1758 cm-1 in the ATR-FTIR spectra confirm the presence of GO and PVP-GO NPs on the surface of TFC by confirming carbonyl and hydroxyl containing groups. The PA layer thickness was measured using ImageJ software in FESEM results, which shows 317 nm, 240 nm and 137 nm thicknesses for TFC, TFN and TFN-1 FO membranes, respectively. Moreover, the AFM results confirm the minimum roughness of TFN-1 compared to TFC and TFN. This study demonstrated that the use of PVP-GO nanoparticles to modify FO membranes significantly enhances their performance. The improved dispersibility of these nanoparticles and the resulting augmented hydrophilicity contribute to higher water flux and better fouling resistance.