Anti-biofouling polyvinylidene fluoride/quaternized polyvinyl alcohol ultrafiltration membrane selectively separates aromatic contaminants from wastewater by host–guest interactions

Abstract

More contaminants are discharged into the water due to industrial activities, resulting in complex wastewater compositions and higher treatment requirements. Hence, a polyvinylidene fluoride/quaternary ammonium polyvinyl alcohol (SPVDF/QPVA) ultrafiltration (UF) membrane with antibacterial properties and host–guest interactions was prepared to meet this challenge. This UF membrane used a QPVA solution as a coagulation bath and then grafted with hydroxypropyl-β-cyclodextrin (HP-β-CD) to provide a host–guest interaction. This work focused on the membrane's anti-biofouling and separation performance for aromatic contaminants. The polyvinylidene fluoride (PVDF)/QPVA UF membrane exhibited an irreversible pollution rate of 2.42% and bacterial deactivation rates of 64.69 and 45.02% against E. coli and S. aureus, respectively. Such performances indicated that the PVDF/QPVA UF membrane reduced the adhesion and reproduction of bacteria on the membrane surface, which mitigated the biofouling of the membrane. After grafting HP-β-CD, the SPVDF/QPVA UF membrane achieved 65.18 and 44.28% bacterial deactivation rates against E. coli and S. aureus, respectively. Moreover, the SPVDF/QPVA UF membrane removed 95% of the proteins, 100% of phenolphthalein, and 87% of β-naphthol from the simulated wastewater. These results were attributed to the synergistic effect of the sieving mechanism and host–guest interaction. Lastly, the SPVDF/QPVA UF membrane displayed good reusability, maintaining an approximately 70% initial removal rate for the simulated wastewater with stable flux and antibacterial performance after 10 treatment cycles. This work provided a new idea for preparing UF membranes and the corresponding preliminary study on mitigating membrane biofouling and removing small molecule contaminants.