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

• Chemical and photochemical reduction of Cr(VI) carried out using H2O2/UV.
• K2Cr2O7 was used as a standard model compound for study.
• The major species of Cr at pH < 6 is HCrO4−.
• Concentration of H2O2 possesses a crucial effect on the reduction of Cr(VI) ion.
• Reduction efficiency decreased with increasing initial concentration of Cr(VI) ion.

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 1.5 M), pH (from 5 to 9), irradiation time (0 to 140 min) and reaction time (0 to 120 min). Initial concentration of Cr(VI) in the solution was varied from 0.1 to 15 mg/L plays a significant role in the mechanism involves for the reduction of noxious Cr(VI) to less toxic Cr(III).

Schematic presentation of setup for carrying out the reduction of Cr (VI) to Cr(III).Figure optionsDownload as PowerPoint slide