Photocatalytic degradation of 2,4-dihydroxybenzoic acid in water: Efficiency optimization and mechanistic investigations

The experimental design and response surface methodologies have been applied to the investigation of the TiO(2)-photocatalytic degradation of 2,4-dihydroxybenzoic acid (DHBA) in aqueous solutions. It has been shown that a quadratic polynomial model may be used to assess adequately the efficiency of the photocatalytic degradation as a function of DHBA and TiO(2) concentrations. Moreover, the study of response surfaces leads to optimal conditions for investigating the catalyst efficiency. A degradation mechanism involving the cleavage of the DHBA aromatic ring at an early stage of the reaction is proposed. Such a mechanism accounts for the absence of any aromatic intermediate in the degradation process. (C) 1997 Elsevier Science S.A.