Photooxidative degradation of cationic dyes using uv/h2o2 and uv/h2o2/tio2 process

Abstract

Photooxidative degradation of maxilon yellow 4GL (MY 4GL) and maxilon red GRL (MR GRL) was studied under different conditions. The effects of pH, TiO2 amount, dye concentration and H2O2 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 H2O2 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.