Phosphotungstic acid-functionalized activated carbon/polysulfone hybrid membranes with enhanced antifouling and filtration performance

Efficient removal of natural organic matter (NOM) from water continues to challenge ultrafiltration (UF) membrane technologies due to fouling-induced flux decline and reduced operational longevity. In this study, we engineered a novel hybrid membrane by incorporating phosphotungstic acid-functionalized activated carbon (PTA@AC) into a polysulfone (PS) matrix via phase inversion at loadings of 1 %, 3 %, and 5 wt%. Comprehensive characterization, comprising FTIR, XRD, TGA, FESEM, AFM, contact angle measurements, and tensile tests, confirmed successful filler integration, enhanced hydrophilicity, structural ordering, and improved thermal and mechanical properties. When tested with humic-acid-laden feedwater, the PTA@AC-containing membranes, especially the 5 wt% variant, delivered substantially higher pure-water flux (≈approximately 175 L m ² h⁻¹) and NOM solution flux (≈approximately 120 L m ² h⁻¹), along with over 98 % rejection for HA, BSA, and alginate. Notably, the 5 wt% membrane also achieved a flux recovery ratio of ∼99 %, irreversible fouling below 12 %, and stable performance across three filtration cycles. These improvements are attributed to the dual-action mechanism: AC enables effective NOM adsorption, while PTA enhances surface hydration and antifouling through acidic polar groups. Our findings demonstrate that PTA@AC/PS hybrid membranes provide a promising, robust strategy for high-performance ultrafiltration with exceptional long-term stability.