PHOTOOXIDATIVE DEGRADATION OF CATIONIC DYES USING UV/H_2O_2 AND UV/H_2O_2/TiO_2 PROCESS

摘要

Photooxidative degradation of maxilon yellow 4GL (MY 4GL) and maxilon red GRL (MR GRL) was studied under different conditions. The effects of pH, TiO_2 amount, dye concentration and H_2O_2 concentration on the process were investigated. Photooxidative reactions followed a pseudo-first order kinetic equation, and the rate constants (k) of reactions were found to be in the range of 0.0066-0.1152 and 0.0001-0.0689 min~(-1) for MY 4GL and MR GRL, respectively. Color removal of both dyes increased with increasing H_2O_2 concentration and the catalyst amount. The degradation of MY 4GL was found to increase with increase of pH from 3 to 5, but a further increase in pH led to decrease in decolorization. On the other hand, in the case of MR GRL, the decolorization decreased with the increase of pH from 3 to 9 but the highest efficiency was observed at pH 3.0. These results revealed that photooxidative degradation was very effective for the decolorization of cationic dyes from aqueous solutions.