Construction of zwitterionic surface of PVDF hollow fiber membrane and the study on the mechanism of “autonomy-response” synergistic enhancement anti-fouling

In this study, polyvinylidene fluoride (PVDF)/styryl maleic anhydride (SMA) hollow fiber membrane was fabricated using the Thermally Induced Phase Separation (TIPS) technique. Subsequently, zwitterion-sulfobetaine methacrylate (SBMA) was introduced to the membrane surface through a Michael addition reaction to create a nearly electrically neutral membrane surface. This modification effectively mitigated the high adsorption of differently charged protein pollutants on the membrane surface, thereby enhancing its anti-fouling performance. Simultaneously, the membrane surfaces with positive and negative charges were separately constructed, and the impact of membrane surface charge properties on the anti-fouling performance against positively and negatively charged foulants was investigated. Furthermore, detailed studies were conducted on the chemical structure, surface morphology, performance, and anti-fouling mechanism of the modified membranes. The results indicate that the electrically neutral membrane modified by zwitterionic SBMA exhibited excellent anti-fouling properties against both bovine serum albumin (BSA) and lysozyme (LYZ), with a flux recovery rate (FRR) reaching 96.5 % and 94.6 %, respectively. The static adsorption capacities of BSA and LYZ on the membrane surface decreased to 5.89 μg cm −2 and 9.53 μg cm −2 , respectively. Furthermore, the study investigated the structure of the hydration layer formed by zwitterionic SBMA on the membrane surface, as well as its hydration capacity and anti-fouling mechanism. Subsequently, through an assessment of the long-term stability of the modified membrane and its flux recovery rate (FRR), in conjunction with theories related to hydration layers and thermodynamics, it elucidated the anti-fouling mechanism involving “autonomy-response” synergistic enhancement of zwitterions. These findings will offer new strategies for researching hollow fiber membranes with superior anti-fouling properties and for applying zwitterions in membrane technology.