Incorporation of graphene oxide/titanium dioxide with different polymer materials and its effects on methylene blue dye rejection and antifouling ability

Abstract

Exposure of synthetic dye, such as methylene blue (MB), in water bodies led to a serious threat to living things because they are toxic and non-degradable. Amongst the introduced dye removal methods, membrane separation process can be considered a powerful technique for treating dye contamination. However, this method commonly suffered from drawbacks, such as short membrane lifetime, low permeability and selectivity. To overcome these issues, graphene oxide (GO) and titanium dioxide (TiO₂) were used as additives to fabricate polyethersulfone (PES)- and polyvinylidene fluoride (PVDF)-based hybrid membranes via non-solvent-induced phase separation method. Prior to membrane fabrication, GO was synthesised via electrochemical exfoliation method assisted by customised triple-tail surfactant. The potential of PES- and PVDF-based hybrid membranes for wastewater treatment has been discussed widely. However, direct comparison between these two polymeric membranes is not critically discussed for MB dye separation application yet. Therefore, this study is aimed at evaluating the performance of different types of polymers (e.g. PES and PVDF) in terms of membrane morphology, properties, dye rejection and antifouling ability. Results showed that the incorporation of GO and TiO₂ alters the morphology of the fabricated membranes and affects dye rejection further, as well as their antifouling performance. In contrast with pristine membrane, PES-GO/TiO₂ and PVDF-GO/TiO₂ possessed high hydrophilicity, as indicated by their low contact angle (67.38° and 62.12°, respectively). Based on this study, PVDF-GO/TiO₂ showed higher porosity value (94.88%), permeability (87.32 L/m²hMPa) and MB rejection rate (92.63%), as well as flux recovery ratio value of > 100% as compared with others. Overall, the incorporation of GO and TiO₂ with PVDF polymer are proven to be effective hybrid materials of membrane fabrication for dye rejection application in the near future. The polymer material's intrinsic properties can affect the attributes of the fabricated membrane.

Keywords: Electrochemically exfoliated graphene oxide; Membrane filtration; Polyethersulfone; Polyvinylidene fluoride; Titanium dioxide.