Kinetics and mechanism
of phenol degradation on TiO2 photocatalyst
S. Qourzal*, M. Tamimi, A. Assabbane, Y. Ait-Ichou
Equipe de Matériaux Photocatalyse et Environnement, Département de Chimie, Faculté des Sciences,
Université Ibn Zohr, B. P. 8106 Cité Dakhla, 80000 Agadir, Maroc
* Corresponding author. E-mail: email@example.com
Received: 30 May 2007; revised version accepted: 24 July 2007
The photocatalytic degradation of phenol in a circular photoreactor, using a UV lamp as a light source and TiO2 as a photocatalyst, was investigated. The effects of various parameters, such as photocatalyst dosage, initial substrate concentration, pH, temperature and addition of oxidants, on the phenol degradation rate of TiO2 photocatalysis were examined. The degradation rates proved to be strongly influenced by these parameters. Adsorption of phenol is a prerequisite for the TiO2-assisted photodegradation. In the presence of both UV light illumination and TiO2 catalyst, phenol was more effectively degraded than with either UV or TiO2 alone. Phenol showed higher photocatalytic oxidation efficiency at natural pH. The reaction rate was found to obey pseudo first-order kinetics represented by the Langmuir-Hinshelwood model. The evolution of CO2 occurred concomitantly with the photomineralization of phenol. Some aromatic intermediate products of phenol were detected by HPLC and GC-MS. A degradation pathway is proposed.
Keywords: Photocatalysis; TiO2; Circular photoreactor; Kinetics; Phenol.