Synthesis of a novel magnetic photocatalyst by direct deposition of nanosized TiO2 crystals onto a magnetic core

This paper presents the preliminary results of a study in which nanocrystalline titanium dioxide particles were directly coated onto a magnetic core. A modified hydrolysed alkoxide process, in which the hydrolysis and condensation of a titanium alkoxide (titanium isopropoxide) was carried out under acidic conditions, using a large water:alkoxide ratio, allowed for the synthesis of crystalline titanium dioxide at relatively low temperatures (90 degreesC). This method is attractive since it eliminated a high-temperature heat treatment step required in a typical sol-gel method, which is needed to transform the amorphous titanium dioxide formed into a photoactive crystalline phase. The prepared particles were photoactive as well as being easy to separate from a slurry-type photoreactor under the application of an external magnetic field. The application of the sol-gel process for the deposition of a crystalline coating of titanium dioxide onto fine particles has never been attempted before. Thus while this approach is envisaged to be quite challenging, its success will provide new fundamental knowledge and tremendous opportunities for the synthesis of tailored particles. (C) 2002 Elsevier Science B.V. All rights reserved.