PHOTOCATALYTIC DEGRADATION OF 2,4-DIHYDROXYBENZOIC ACID IN WATER - EFFICIENCY OPTIMIZATION AND MECHANISTIC INVESTIGATIONS

The experimental design and response surface methodologies have been a pplied to the investigation of the TiO2-photocatalytic degradation of 2,4-dihydroxybenzoic acid (DHBA) in aqueous solutions. It has been sho wn that a quadratic polynomial model may be used to assess adequately the efficiency of the photocatalytic degradation as a function of DHBA and TiO2 concentrations. Moreover, the study of response surfaces lea ds 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 accou nts for the absence of any aromatic intermediate in the degradation pr ocess. (C) 1997 Elsevier Science S.A.