The Study Of Factors For TiO₂ Photocatalytic Reduction Kinetic Of Bromate

As the potential carcinogenic effects of bromate on human, which threat the health of people, how to removal bromate in water efficient has become an urgent problem. In recent years, photocatalytic removal of bromate have been carried on and preliminary kinetic study had finished for the photocatalytic reaction of Pt/TiO₂. But further research of influencing factors of TiO₂ photocatalytic removal of bromate still to be studied.This project will stduy the effact of various experimental factors on the reaction. The major elements as followed:1) The results of kinetic study show that, the reaction is the first-order kinetic reaction when the initial concentration of bromate is 50ppb. And the reaction of other concentrations, such as 100, 200, 300, 500ppb, are zero-order kinetics reaction. The impact of the dosage of TiO₂ on the photocatalytic reaction. The resules show that in this experiment, durning the six set pH values(3,5,7,9) the activity is highest when the pH value is 5; the optimal dosage of TiO₂ is 0.05g/300 mL. All reactions are Zero-order kinetics.2) Study the effects of conventional anions in water (CO32-,PO43-,NO3-,SO42-), halogen anions (F-,Cl-,Br-,I-) on the photocatalytic reduction of bromate. The results show that CO32- promote the reaction in low concentration and inhibit it in high concentration; the PO43- will inhibit the reaction and the effect will be strengthen with the increasing of concentration of PO43-; NO3- and SO42- can promot the reaction when concentrations of them equal to or as 50 times as concentration of bromate. F- and I- both promote the reaction, and the promoting increased at first and then decreased with the increase of concentration of F- ande I-, the impact of I- is stronger than F-; Br- inhibit the reaction with low concentration, and promot the reaction with the high concentration when the Cl- have no effect on the reaction. The results alse show that the addition of these anions in the reation solution will change the kinetic of reaction, and most reactions become one order reaction; small proportion of reactions will be zero-order reaction.3) Study the effects of conventional cations (Cu²⁺, ferric iron, trivalent aluminum, Ca²⁺, Na⁺) on the photocatalytic reduction of bromate. The results show that Cu²⁺ will promot the reaction when the concentration of it equal to BrO₃^-, and the effect will be increased first and the decreased with the increasing of concentration of Cu²⁺; ferric iron promot the reaction and the effect will be stronger with the increasing of concentration of ferric iron; trivalent aluminum will inhibit the reaction and the effect will be stronger with the increasing of concentration of trivalent aluminum;Ca²⁺ and Na⁺ will promote the reaction, and with the concentration increasing, the roles in promoting enhanced. The results alse show that all the reaction with three different concentrations of Cu²⁺and ferric iron are first order kinetic progress; when the concentration of Na⁺ as 10 times and 50 times as the concentration of BrO₃^-, the reaction is first order kinetics, and the reaction with the same concentration of Na⁺ is zero-order kinetics process; adding three concentrations of trivalent aluminum and Ca²⁺ did not change when the kinetics of the reactions.