Abstract

Polyethersulfone (PES)-based nanofiltration membranes were fabricated by incorporating CuFe₂O₄/Ag composite nanoparticles (CNPs) to enhance permeability, hydrophilicity, and antifouling performance. The CuFe₂O₄/Ag CNPs was synthesized via an environmentally benign co-precipitation method using arginine as a natural reducing agent, and ATR-FTIR together with FESEM analyses confirmed its characteristic functional groups, uniform morphology, and homogeneous elemental distribution; similarly, ATR-FTIR and FESEM characterization of the CuFe₂O₄/Ag-incorporated membrane verified the successful embedding of the nanoparticles, the appearance of new functional interactions within the polymer matrix, and a uniformly modified surface morphology. Mixed matrix membranes were prepared by the phase inversion technique at various CNPs loadings (0.001–1.0 wt%), and their physicochemical properties were systematically evaluated. The addition of CuFe₂O₄/Ag CNPs significantly reduced the water contact angle from 70° to 45° and increased membrane porosity from 75% to 89%, improving surface hydrophilicity and pore interconnectivity. The optimized membrane (0.1 wt%) exhibited a 2.5-fold increase in pure-water flux (from 12 to 29.0 L·m⁻²·h⁻¹) and achieved 94% Na₂SO₄ rejection. Moreover, it demonstrated excellent heavy-metal ion removal efficiencies, with 93% and 81% rejection for Cu(II) and Cr(II), respectively. The flux recovery ratio (FRR) markedly improved from 61% for pristine PES to 88% for the modified membrane, indicating enhanced antifouling resistance. These improvements are attributed to the synergistic effects of the hydrophilic CuFe₂O₄/Ag CNPs, which enhanced charge selectivity, pore uniformity. Overall, the CuFe₂O₄/Ag–PES nanocomposite membranes exhibited superior water flux, ion selectivity, and fouling resistance, demonstrating strong potential for sustainable wastewater treatment and desalination applications.