Photodegradation of polyaromatic hydrocarbons over thin film of TiO2 nanoparticles; a study of intermediate photoproducts

The photocatalytic degradation of saturated aqueous solution of naphthalene and anthracene was studied over thin films of porous TiO2 particles on gla ss substrate, prepared by sol-gel process. Surface morphology and structura l features were studied by SEM, TEM and Laser Raman Spectroscopy. These fil ms have been found to be very efficient and the total photomineralisation o f these organics to carbon dioxide and water occurs in air-equilibrated sol ution within 1 h. Concentration changes linearly with the illumination time , and high rate constants are obtained for the degradation of these organic s. The pH of the solution changes with the irradiation time due to the form ation of intermediate photoproducts, e.g., 5,8-dihydroxynaphthaquinone, and 9,10-anthraquinone, etc. Photodegradation mechanism and the detection of r eaction intermediates have been discussed in details. (C) 2000 Elsevier Sci ence B.V. All rights reserved.