Multifunctional hybrid UF membrane from poly(ether sulfone) and quaternized polydopamine anchored reduced graphene oxide nanohybrid for water treatment

In this study, a new quaternized polydopamine anchored reduced graphene oxide (QSiPD-rGO) nanohybrid was prepared through a one-step mussel-inspired tailoring of GO using a quaternized silica precursor and dopamine. The QSiPD-rGO was applied for the first time as a nanofiller, at a significant loading rate of up to 8 wt%, to manufacture positively charged, high flux, fouling resistant and antibacterial hybrid poly(ether sulfone) (PES) ultrafiltration (UF) membranes, via non-solvent induced phase separation. A suite of tools was utilized to thoroughly characterize the nanohybrid and the membranes, including SEM-EDX, Raman, ATR-FTIR, TGA, AFM, zeta potential and contact angle measurements. The surface morphology, charge and hydrophilicity of the membranes were tuned upon integrating the nanohybrid. Consequently, pure water flux significantly increased, reaching ~ 270 L m⁻² h⁻¹ (at 1 bar) for PMQ4 with 6 wt% QSiPD-rGO loading. This was 94% higher than the corresponding flux of pristine membrane (139 L m⁻² h⁻¹, at 1 bar). The hybrid membranes also showed superior fouling resistance during the UF of 500 ppm bovine serum albumin (BSA) solution. The BSA rejection rate of the hybrid membranes was very high and uncompromised by their high flux, exceeding 98% for PMQ4. Additionally, a remarkable antibacterial activity (against E. Coli.) of the membranes was induced by the nanohybrid, with a strong correlation between this activity and QSiPD-rGO loading.