| Summary: | 碩士 === 國立中興大學 === 環境工程學系所 === 104 === The aim of the study is to remove the wastewater containing EDTA and Hexavalent chromium and investigating the photocatalytic ability of TiO2. This research compared the difference of the photocatalysts between the before-photocatalytic reaction and after-photocatalytic reaction. The surface properties of photocatalysts were characterized by color、SEM、EDS、XRD、FTIR、BET and zeta potential analysis. And then, it compared the mix system（containing Hexavalent chromium and EDTA）and single system（only Hexavalent chromium）. By controlling the pH （3、6、10）、the dosage of photocatalysts（0.1 g、0.25 g、0.5 g）、the mole ratio of contaminants（EDTA/Cr = 0.5、1、2）in photocatalytic experiments, the optimal operating parameters could be found. Finally, investigated the chelating effect to the photocatalytic efficiency.
The result of surface properties indicated the photocatalysts becomed green and the solution becomed purple were attributed to reduce Hexavalent chromium to Trivalent chromium. After the photocatalytic reaction, the appearance of catalysts and the zeta potential did not change and the BET was decreased. TiO2 was not formed chemical bonding with catalysts. The result of photocatalytic experiments indicated the photocatalytic efficiency of mix system was better than single system. The optimal pH value was pH 3、dosage of TiO2 was 0.5g、mole ratio（EDTA/Cr）was 1. In addition, the removal efficiency of Hexavalent chromium and EDTA could reach 100 % at the optimal operating condition within 90 min. With the higher concentration of EDTA-Cr in system, the degradation efficiency of Hexavalent chromium was decreased.
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