Affiliations: State Key Laboratory of Pollution Control and Resource
Reuse, School of Environment, Nanjing University, Nanjing 210093, China | Institute of Atomic Energy, Jiangsu Academy of
Agriculture Sciences, Nanjing 210014, China
Abstract: 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 of Cr(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.
Keywords: γ-irradiation, radiation-induced reduction of Cr(VI), hydroxyl radical scavengers, kinetics
