Sol–gel preparation of titania multilayer membrane for photocatalytic applications

The main goal of the present study is to prepare a titania membrane with high permeability and photocatalytic activity for environmental applications. In this investigation a mesoporous titania multilayer membrane on alumina substrate is successfully fabricated via the sol–gel processing method. The prepared titania polymeric sol for the membrane top layer has an average particle size of 11.7 nm with a narrow distribution. The resulting TiO2 multilayer membrane exhibits homogeneity with no cracks or pinholes, small pore size (4 nm), large specific surface area (83 m2/g), and small crystallite size (10.3 nm). The permeability and photocatalytic properties of the titania membrane were measured. The photoactivity of the titania membrane was examined to be 41.9% after 9 h UV irradiation based on methyl orange degradation. This measurement indicates high photocatalytic activity per unit mass of the catalyst. Through multilayer coating procedure, the photocatalytic activity of the membrane improved by 60% without sacrificing the membrane permeation. The prepared TiO2 photocatalytic membrane has a great potential in developing high efficient water treatment and reuse systems due to its multifunctional capability such as decomposition of organic pollutants and physical separation of contaminants.