Phenol destruction by photocatalysis on TiO2: an attempt to solve the reaction mechanism

Six hydroxylated aromatic compounds, p-benzoquinone and four aliphatic compounds were detected as intermediates of the reaction of phenol photocatalytic oxidation in the presence of illuminated TiO2. The concentration of catechol, hydroquinone and p-benzoquinone was determined quantitatively along with that of phenol in the course of the photoreaction. The reactions of TiO2-photooxidation of phenol and its primary intermediates-dihydroxybenzenes show 1st order behaviour. The use of initial reaction rates for kinetic studies is recommended because of many competitive reactions in illuminated suspensions of titanium dioxide. A possible mechanism of phenol full mineralisation is presented. (C) 2003 Elsevier B.V. All rights reserved.