Dual-antifouling strategy of MC-67 composite membranes for pool water treatment

To address salt-induced scaling challenges in ultrafiltration and the removal of contaminants from swimming pool water, a hydrophilic catalytic membrane (MC-67 MEM) was developed via “wedge”-assisted mechanical ultrasonic stripping of 3D crystalline ZIF-67 and combined with peroxymonosulfate (PMS) activation for fouling mitigation under varying salinity conditions (0–100 mM). When humic acid (HA) was used as a model foulant, the MC-67 MEM/PMS/Cl⁻ system demonstrated superior antifouling performance, with 29.4%–95.9% reduction in reversible fouling resistance and 17.3%–163.4% increase in normalized fluxes (J/J₀) compared with those of the control. Fluorescence excitation-emission matrix (EEM) analysis combined with parallel factor analysis (PARAFAC) analysis in real pool water confirmed reduced accumulation of humic-like substances on MC-67 MEM. This improvement was attributed to the generation of reactive chlorine species (RCSs) and strong polar repulsion forces near the membrane surface. XDLVO theory showed that antifouling relies primarily on strong polar repulsion (AB interactions) of HA in the 4.5 nm range of the surface. Furthermore, PMS activation facilitated HA degradation via RCS pathways, mitigating both pore blockage and cake layer formation. The simulation of the dynamic membrane fouling process via a combined pore blockage-cake filtration model further revealed a salinity-dependent transition in fouling mechanisms from intermediate to standard blocking. This study elucidates a dual mitigation strategy that combines catalytic oxidation and surface engineering for the effective treatment of pool circulating water.