Radiation-induced reduction of chromium(Ⅵ) in aqueous solution by γ-irradiation in a laboratory-scale

Radiation-induced reduction of chromium（Ⅵ）（Cr（Ⅵ） by ,γ-irradiation was studied with an initial concentration of 42 mg/L in aqueous solutions. Several factors which might affect the reduction of Cr（Ⅵ） to Cr（Ⅲ） were examined, pH of aqueous solution affects the reduction efficiency significantly. Acidic condition of aqueous solution accelerates the process. At pH 2, a reduction of 86.2% was achieved with the absorbed dose of 15 kGy, while, with the same dose, at pH 5 and 7, the reduction ofCr （Ⅵ） were only 36.3% and 22.2%, respectively. Ethanol （0.1% in V：V） and sodium carbonate （1 mmol/L） were added into the solution respectively as relatively non-toxic hydroxyl radical scavengers. Reduction rate increased greatly in the presence of ethanol at each pH. Reduction efficiency of Cr（Ⅵ） was enhanced in neutral condition with the addition of sodium carbonate, however, no enhancement was found in acidic condition. The reduction of Cr（Ⅵ） was restrained when the solution was saturated with oxygen; however, the restraint was not significant.