Foundation of Kinetics Model for TiO_2-Photocatalyzed Degradation of Organic Compounds in Suspending System

With O,S dimethyl acetyl phosphoramidothioate(DMAPT) as objective compound, the kinetics model for TiO 2 photocatalyzed degradation in suspending system was studied in DGF 1 model photochemistry reaction instrument. The main parameters involved in the model are TiO 2 dosage , effective light intensity, geometrical radius and empirical parameter of the reactor, initial concentration of the reactant, rate constants of the second order reaction of OH· radical, and physical properties of the reactant(such as molar volume and aqueous solubility). The different DMAPT concentrations were used to validate the funtion. The model preferably predicted the photocatalytic degradation of other compounds, such as trichloroethylene(TCE), tetrachloroethylene(PCE), p dichlorobeneze(DCB) and carbon tetrachloride(CTC). For the system with C 0(TCE)=22.1 mg/L , C 0(PCE)=20 mg/L, C 0(DCB)=40 mg/L, the time needed for complete degradation is 3, 4 and 5 min respectively. The reaction rate is proportional to the half order of incident light intensity within the range of 1.38～6.05 W/cm 2. The optimum catalyst dosage increases with increasing the incident light intensity.