Reduction of noxious Cr(VI) ion to Cr(III) ion in aqueous solutions using H2O2 and UV/H2O2 systems

Conversion of the toxic Cr(VI) to the less toxic Cr(III) in aqueous solutions by chemical and photochemical reduction was carried out using H2O2 and UV radiation. The whole mechanism was well elucidated and investigated using potassium dichromate (K2Cr2O7) as a standard model compound. The effects of potential factors affecting the reduction efficiency were well studied and optimized, the optimized parameters such as concentration of H2O2 (from 0.5 to 1.5M), pH (from 5 to 9), irradiation time (0 to 140min) and reaction time (0 to 120min). Initial concentration of Cr(VI) in the solution was varied from 0.1 to 15mg/L plays a significant role in the mechanism involves for the reduction of noxious Cr(VI) to less toxic Cr(III).