Poly(styrene-alt-chitosan malonate)/poly(ether sulfone) blend membranes for ultrafiltration with enhanced antifouling performance

In this study, novel poly(styrene-alt-chitosan malonate)/polyethersulfone (MPPSMCS/PES) blend membranes were fabricated via the non-solvent induced phase separation (NIPS) technique and evaluated for their ultrafiltration performance and antifouling properties. The incorporation of the hydrophilic copolymer was aimed at improving membrane porosity, surface hydrophilicity, and resistance to organic fouling, particularly from humic acid (HA). Structural and physicochemical characterizations using FTIR, XRD, TGA, SEM, and AFM confirmed successful integration of the composite. They revealed enhanced thermal stability, surface roughness, and pore structure with increasing composite loading. The 5 % MPPSMCS membrane exhibited the highest porosity (≈76 %), water uptake (≈73 %), and the lowest contact angle (≈53°), indicating improved hydrophilicity. Correspondingly, this membrane achieved the highest pure water flux (∼290 L·m⁻²·h⁻¹) and HA rejection efficiency (∼98 %), along with a significantly reduced HA adsorption (∼18 μg/cm²). Antifouling evaluation across three filtration–cleaning cycles demonstrated that MPPSMCS membranes retained high flux recovery ratios (FRR > 85 %) and exhibited low irreversible fouling, outperforming neat PES membranes. The improved performance is attributed to the synergistic effects of surface functionalization, optimized pore morphology, and enhanced mechanical stability. These findings suggest that MPPSMCS/PES blend membranes are promising candidates for high-efficiency, fouling-resistant ultrafiltration applications in water treatment.