Preparation of photo‑catalytic copolymer grafted asymmetric membranes (N‑TiO2‑PMAA‑g‑PVDF/PAN) and their application on the degradation of bentazon in water

Abstract

Nitrogen-doped titanium dioxide (N–TiO2) was prepared and supported on a novel copolymer grafted membrane matrix to avoid the problems associated with the removal of spent photocatalyst from treated water. Membranes of poly (methacrylic acid) grafted onto poly (vinylidene difluoride) and blended with poly (acrylonitrile) (PMAA-g-PVDF/PAN) were prepared through a dry–wet phase inversion technique. Methacrylic acid side chains were grafted onto an activated PVDF backbone by the method of reversible addition fragmentation chain transfer polymerization and then the novel photocatalytic asymmetric membranes of N–TiO2–PMAA-g-PVDF/PAN were prepared. The casting solutions were blended with 1–5 % N–TiO2 before immersion into the coagulation bath. PVDF and PAN offer several advantages which include: mechanical strength and toughness, chemical resistance, unaffected by long-term exposure to UV radiation, low weight, and thermal stability. N–TiO2 was prepared through sol-gel synthesis. The photocatalytic membranes were evaluated by degradation process of herbicide bentazon in water. Photodegradation studies revealed that the optimum photocatalyst loading was 3 % N–TiO2 and the optimum pH was 7 for the degradation of bentazon in water. UV– Vis, TOC and LC–MS analyses confirmed the successful