Structure and photocatalytic performance of magnetically separable titania photocatalysts for the degradation of propachlor

A magnetic photocatalyst was prepared by modification of TiO2 nanoparticles (Degussa P25) with nanocrystalline gamma-Fe2O3 nanoparticles through a protective lining made up of two oppositely charged polyelectrolytes. As-prepared magnetically separable photocatalysts differing in gamma-Fe2O3 loading (3, 8, 13, 20 and 30 wt.%) were characterized by XRD, TEM, thermal analysis, Mossbauer and magnetic measurements. The photocatalytic efficiency of the nanocomposite catalysts was evaluated using a chloroacetanilide herbicide (propachlor) in water as model compound. The primary degradation of propachlor followed pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Generally, all magnetic photocatalysts exhibit good catalytic activity towards organic pollutants, do not suffer from photodissolution and can be reused several times without any decrease in their photocatalytic activity. (C) 2008 Published by Elsevier B.V.