Photochemical oxidation of persistent cyanide-related compounds

Abstract

Kinetic regularities of the photolysis of thiocyanate solutions using of mono- and polychromatic UV radiation sources with different spectral ranges are studied. Comparative experiments aimed at investigating the role of photochemical action during the oxidation of thiocyanates with persulfates and additional catalytic activation with iron(III) ions are performed. The rate of conversion and the initial rate of thiocyanate oxidation are found to change in the order UV < UV/S₂O₈²⁻ < S₂O₈²⁻/Fe³⁺ < UV/S₂O₈²⁻/Fe³⁺. A synergistic effect is detected when using the combined catalytic method for the destruction of thiocyanates by the UV/S₂O₈²⁻/Fe³⁺ oxidation system. This effect is due to the formation of reactive oxygen species, as a result of both the decomposition of persulfate and the reduction of inactive Fe³⁺ intermediates into Fe³⁺.