Reaction of Cu(CN)32- with H2O2 in water under alkaline conditions: Cyanide oxidation, Cu+/Cu2+ catalysis and H2O2 decomposition

Cuprous cyanide is widely present in electroplating wastewater or metallurgical effluents. In the present study, the destruction of Cu(CN)(3)(2-) with H2O2 in water under alkaline conditions was investigated. H2O2 oxidized the cyanide from Cu(CN)(3)(2-) to cyanate with the formation of Cu(CN)(2)- firstly. Following, the continuous oxidation of cyanide from Cu(CN)(2)- and the attendant dissociation of Cu(CN)(2)- led to progressive liberation of Cu+. Transformation of Cu+ to Cu2+ was confirmed afterward by X-ray photoelectron spectroscopy analysis. Meantime, the center dot OH signal was detected by electron spin resonance assay. It was concluded that Fenton-like reaction occurred between the liberated Cu+ and H2O2. UV-vis spectra studies revealed the formation of superoxo-cupric complex between Cu2+ and H2O2 in alkaline conditions, which decomposed into Cu2+ species and O-2 finally. Thus, how to improve the utilization of H2O2 and enhance the destruction of Cu(CN)(3)(2-) should be considered in the treatment of Cu(CN)(3)(2-) wastewater. (C) 2014 Elsevier B.V. All rights reserved.