Composite membranes for enhanced anti-fouling and heavy metal ion removal

This study investigated the use of carboxylated graphene oxide (GO-COOH) and sulfonated polyetheretherketone (SPEEK) to modify PMIA nanofiltration membranes synergistically for the removal of heavy metal ions from wastewater, and systematically investigated for five heavy metal ions, As(V), Cr(VI), Cd2+, Pb2+ and Zn2+.FTIR analysis reveals that carboxyl groups of GO-COOH and sulfonic acid groups of SPEEK are present on the membrane surface, and the spectral data are suggestive of hydrogen bonding interactions between them. Contact angle testing revealed that the composite film significant increase in hydrophilicity. The PGS membrane achieves water flux of 149.3 L/m2/h at 0.8 MPa and exhibits the rejection over 95% for five heavy metals and all higher than PG and PMIA membranes. Mechanistic analysis indicates that the high negative charge density on the membrane surface enables efficient retention of heavy metal ions through the Donnan effect. Anti-fouling performance tests show that the PGS membrane has excellent anti-fouling properties against bovine serum albumin (BSA), with a flux recovery rate of over 99%. This study confirms that simultaneously enhancing the permeability, selectivity, and fouling resistance of PMIA membranes through the synergistic modification of GO-COOH and SPEEK provides a theoretical basis for developing high-performance heavy metal removal membranes.