Radio-lytic degradation of reactive dyes in aqueous solution: comparative analysis using gamma/H₂O₂ and UV/H₂O₂ processes

In this study, gamma/H2O2 and UV/H2O2 treatment procedures were used for the degradation of five dyes including reactive red PB (R-24), reactive orange P3LN (O-13), reactive turquoise blue PG (B-21), reactive golden yellow H2R (O-12) and reactive lemon yellow C(4)G L (Y-15). The dye samples of 50 or 100 ppm concentration were treated with either gamma (0-10 kGy) or UV radiations in the presence/absence of H2O2. This treatment resulted in the elimination of chromophoric groups and degradation of dye molecule into low molecular weight fragments. The H2O2 treatment caused the generation of hydroxyl radicals which degraded the pollutants non-selectively by means of chain oxidation process. The treatment effectiveness was increased when H2O2, which was used in conjunction with UV or gamma radiation and the treated water quality, improved significantly. However, the gamma/H2O2 treatment was found to be the more effective and efficient method as compared to the UV/H2O2 treatment for the removal of dyes from the water.