Role of Membrane–Solute Affinity Interactions in Carbamazepine Rejection and Resistance to Organic Fouling by Nano-Engineered UF/PES Membranes

In this study, polyethersulfone (PES) ultrafiltration (UF) membranes were modified with GO, Ag, ZnO, Ag-GO and ZnO-GO nanoparticles to improve carbamazepine removal and fouling prevention by making membrane surfaces more hydrophilic. The fabricated membranes were characterized for surface and cross-sectional morphology, surface roughness and zeta potential, as well as hydrophilicity, functional groups, surface tension parameters and water permeability Thereafter, the membranes were evaluated for their efficiency in removing MgSO₄ and carbamazepine as well as antifouling properties. To understand the role of affinity interactions in rejection and fouling, membrane–solute adhesion energies (${∆G}_{slm}$) were quantified based on the Lifshitz–van der Waals/acid–base method. Unlike previous studies, which have generalized fouling prevention to be due to improvements in hydrophilicity upon adding nanoparticles, this work further explored the role of surface tension components on rejection and fouling prevention. The addition of nanoparticles improved membrane hydrophilicity (77–62°), water permeability (11.9–17.7 Lm⁻² h⁻¹ bar⁻¹), mechanical strength (3.46–4.11 N/mm²), carbamazepine rejection (30–85%) and fouling prevention (60–23% flux decline). Rejection and antifouling properties increased as ${∆G}_{slm}$ became more repulsive (i.e., less negative). Membrane modification reduced irreversible fouling, and the fouled membranes were cleaned by flushing with water. Fouling related more to membrane electron donor components (${\gamma }^{-}$), while the roles of electron acceptor (${\gamma }^{+}$) and Lifshitz–van der Waals components (${\gamma }^{LW}$) were less important. This work provides more insights into the role of affinity interactions in rejection and fouling and how rejection and fouling mechanisms change with nanoparticle addition.