Synthesis of High-Antifouling and Antibacterial Ultrafiltration Membranes Incorporating Low Concentrations of Graphene Oxide

Abstract

Membrane treatment for wastewater treatment is one of the promising solutions to affordable clean water. It is a developing technology throughout the world and considered as the most effective and economical method available. However, the limitations of membranes’ mechanical and chemical properties restrict their industrial applications. Graphene Oxide (GO) is one of the materials that have been recently investigated in membrane water treatment sector. In this work, ultrafiltration polysulfone (PSF) membranes with high antifouling properties were synthesized by incorporating different loadings of GO. High-oxidation degree GO had been synthesized using modified Hummers’ method. The synthesized GO was characterized using different analytical techniques including (FTIR-UATR), Raman spectroscopy, and CHNSO elemental analysis that showed high oxidation degree of GO represented by the its oxygen content (50 wt.%). Morphology and hydrophilicity of membranes were investigated using SEM, AFM and contact angle analyses and showed clear effect of GO on PSF morphology and better hydrophilicity of GO-based membranes caused by the hydrophilic nature of GO and its high oxygen content. Separation properties of the prepared membranes were investigated using a cross-flow membrane system. Biofouling and organic fouling resistance of membranes were tested using bovine serum albumin (BSA) and humic acid (HA) as model foulants. It has been found that GO based membranes exhibit higher antifouling properties compared to pure PSF. When using BSA, the flux recovery ratio (FRR %) increased from 65.4 ± 0.9 % for pure PSF to 86.9 ± 0.1 % with loading of 0.1 wt.% GO in PSF. When using HA as model foulant, FRR increased from 87.8 ± 0.6 % to 95.6 ± 4.2 % with 0.1 wt.% of GO in PSF. The pure water permeability (PWP) decreased with loadings of GO from 181.7 L.m-2.h-1.bar-1 of pure PSF to 181.1 and 167.4 L.m-2.h-1.bar-1 with 0.02 and 0.1 wt.% GO respectively. Furthermore, GO based membranes exhibited effective antibacterial performance against Halomonas aquamarina compared to pristine PSF. It can be concluded from the obtained results that incorporating low loading of GO could enhance the antifouling and antibacterial properties of PSF hence improving its lifetime and reuse.