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Photocatalytic Degradation of EDTA by Using TiO2 Suspension

Ayad F. Alkaim and Falah H. Hussein

The photocatalytic degradation of an aqueous solution of ethylene diamminetetra-acetic acid (EDTA) has studied under different conditions in the presence of TiO2 suspension. The effect of various parameters such as mass of titanium dioxide, EDTA concentration, light intensity, addition of H2O2 and flow rate of O2 on the photocatalytic degradation were investigated. Results showed that, the photocatalytic degradation process was high at the beginning and then decreased with time. This process was well described by pseudo, first order kinetics according to the Langmuir-Hinshelwood model. The results explained the photocatalytic degradation efficiency, which was increased by increasing catalyst loading from 1 g to 2 g. The degradation efficiency decreased with the increase in catalyst loading. Results also showed that the rate of photocatalytic degradation was increased with decreasing EDTA concentration. The proper amount of hydrogen peroxide improved the rate of photocatalytic degradation of EDTA, while the excess hydrogen peroxide quenched that formation of hydroxyl radicals •OH, which caused reducing at the rate of photocatalytic degradation. The effect of dissolved oxygen level of bubbling pure oxygen gas into the solution has been found to enhance the photodegradation rate. Results indicated that the photocatalytic degradation was enhanced by increasing light intensity.