Well-organized, mesoporous nanocrystalline TiO2 on alumina membranes with hierarchical architecture: Antifouling and photocatalytic activities

We report the development of improved antifouling and photocatalytic membranes based on an organized mesoporous TiO2 (om-TiO2) layer on a porous alumina (Al2O3) support. The om-TiO2 layer was templated by an amphiphilic graft copolymer, i.e., poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM), and was 50-70 nm in pore size with high porosity and good pore interconnectivity. The precoating of poly(vinyl pyrrolidone) (PVP) on a porous alumina support was the key to providing a flat platform and improving the adhesion properties of alumina with TiO2, which allowed for the formation of om-TiO2 membranes. Fouling of photocatalytic om-TiO2 on the alumina membrane was also investigated using a laboratory-scale photocatalytic dead-end filtration reactor using a model dye compound. The fouling rate was observed to be much slower for the om-TiO2 membrane compared to the bare alumina support under UV illumination during 6h of membrane operation. The PVP precoating on the alumina support improved the permeation quality of the om-TiO2 membrane. The improved removal of the organic dye compound was thought to result from the enhanced adsorption capability of organic compounds and subsequent photocatalytic reactions on the om-TiO2 layer. However, UV illumination performed for longer than 6h gradually increased the fouling rate due to the deposition of the organic dye compound on the membrane surface, and prohibited the accessibility of the UV light to the TiO2 layer. (C) 2016 Elsevier B.V. All rights reserved.