Immobilization of Bi2WO6 on Polymer Membranes for Photocatalytic Removal of Micropollutants from Water - A Stable and Visible Light Active Alternative.

Abstract

In this work, bismuth tungstate Bi2WO6 is immobilized on polymer membranes to photocatalytically remove micropollutants from water as an alternative to titanium dioxide TiO2. A synthesis method for Bi2WO6 preparation and its immobilization on a polymer membrane is developed. Bi2WO6 is characterized using X-ray diffraction and UV-vis reflectance spectroscopy, while the membrane undergoes analysis through scanning electron microscopy, X-ray photoelectron spectroscopy, and degradation experiments. The density of states calculations for TiO2 and Bi2WO6, along with PVDF reactions with potential reactive species, are investigated by density functional theory. The generation of hydroxyl radicals OH• is investigated via the reaction of coumarin to umbelliferone via fluorescence probe detection and electron paramagnetic resonance. Increasing reactant concentration enhances Bi2WO6 crystallinity. Under UV light at pH 7 and 11, the Bi2WO6 membrane completely degrades propranolol in 3 and 1 h, respectively, remaining stable and reusable for over 10 cycles (30 h). Active under visible light with a bandgap of 2.91eV, the Bi2WO6 membrane demonstrates superior stability compared to a TiO2 membrane during a 7-day exposure to UV light as Bi2WO6 does not generate OH• radicals. The Bi2WO6 membrane is an alternative for water pollutant degradation due to its visible light activity and long-term stability.