Synthesis of polyethersulfone (PES)/GO-SiO₂ mixed matrix membranes for oily wastewater treatment

The treatment of oily wastewater continues to pose a challenge in industries worldwide. Membranes have been investigated for their use in oily wastewater treatment due to their efficiency and relatively facile operational process. Graphene oxide (GO) and SiO₂ nanoparticles were found to improve membrane properties. A polyethersulfone (PES) based GO-SiO₂ mixed matrix membrane (MMM) was prepared, using the phase inversion technique, for the treatment of oil refinery wastewater. The PES/GO-SiO₂ membrane demonstrated the highest water flux (2561 LMH) and a 38% increase in oil removal efficiency by comparison to a PES membrane. Compared to PES/GO and PES/SiO₂ membranes, the PES/GO-SiO₂ MMM also showed the best overall properties in terms of tensile strength, water permeability, and hydrophilicity. The difference in oil rejection values across the membranes was attributed to the increasing negative charges on the surface of the modified membranes which interfered with the positive ions present in the oily wastewater sample.