Sumiko Sanuki1, Daiki Kaizawa1, and Hiroshi Majima2,
1Department of Material Systems Engineering and Life Science, Faculty of Engineering, Toyama University, addressToyama 930-8555
Decomposition of tartarate during the photocatalytic reduction of Cu(II)-tartarate complex alkaline solution whose pH was adjusted with NaOH was studied using TiO2 powders. The effects of various factors, such as concentrations of NaOH and potassium sodium tartarate, intensity of UV irradiation and identity of TiO2 powders, were investigated on decomposition rate of tartarate. The main findings obtained are as follows: In the concentration range of 0.1~0.3 kmol⋅m-3 NaOH, both Cu(II) reduction and tartarate decomposition rates tend to linearly increase with the increase in NaOH concentration. As far as the same TiO2 catalyst was used, the adsorption amount of free tartarate ion as well as Cu(II)-tartarate complexes ions onto TiO2 catalyst increase with the increase in NaOH concentration, indicating that adsorption of these ions directly concerns to the photocatalytic reaction. The amount of tartarate decomposition was around 10% of Cu(II) reduction. We detected CO32- ions as the decomposed product, indicating a photocatalytic oxidation route of tartarate decomposition. Although the reduction rate of Cu(II) greatly decreased with the decrease in tartarare concentration, initial decomposition rates of tartarate were almost same despite of initial tartarate concentration. However, tartarate decomposition rates sharply increase near the termination of Cu(II) reduction reaction, showing more effective increase with the increase in initial tartarate concentration. By using different TiO2 catalysts, the amount of tartarate onto catalyst were affected by both surface area and adsorption activity of catalyst used. However, tartarate decomposition rate was not directly affected by the amount of tartarate adsorption in this case.
(Received May 21, 2003)
decomposition of tartarate, photocatalytic reaction, Cu(II)-tartarate complex, TiO2 powder
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