Charge-enhanced sulfonated block copolymer composite membrane for whey recovery

• Successfully prepared sulfonated block copolymer mPEG-b-SPAN. • Composite membrane achieved a high protein/salt separation performance. • Composite membrane exhibits good antifouling properties against various proteins. As global demand for dairy products increases, the processing of whey, a highly contaminated by-product, necessitates stringent treatment. However, due to its rich nutritional profile, whey has garnered attention as a valuable resource. Addressing the high salt concentration in whey waste through the development of sustainable separation technologies offers an effective strategy for the efficient recovery and valorization of whey proteins. In this study, sulfonated polyacrylonitrile (SPAN), methoxy-polyethylene glycol-block-polyacrylonitrile (mPEG-b-PAN), and methoxy-polyethylene glycol-block-sulfonated polyacrylonitrile (mPEG-b-SPAN) were synthesized to prepare ultrafiltration membranes with enhanced selectivity and antifouling properties. The incorporation of sulfonic acid groups and mPEG segments significantly altered the membrane’s surface roughness and reduced the thickness of the selective layer. The optimized M3 membrane, produced by blending mPEG-b-SPAN with polyacrylonitrile (PAN), exhibited remarkable water permeability of 402.9 L m −2 h −1 bar −1 , owing to the synergistic effects of mPEG and sulfonic acid groups on the membrane surface. It achieved retention rates exceeding 99.0 % for whey protein (WP), bovine serum albumin (BSA), and casein (CN), while maintaining a low retention rate of less than 1.0 % for sodium chloride (NaCl), facilitating the effective separation of proteins and salts. Furthermore, antifouling performance tests demonstrated that the M3 membrane displayed high flux recovery and minimal irreversible fouling during contamination tests. These findings suggest that mPEG-b-SPAN block copolymers hold significant potential for high-salt whey protein recovery, providing a strong foundation for advancing protein separation technologies.