Degradation of ferrohexacyanide by advanced oxidation processes

Abstract

Degradation of ferrohexacyanide in aqueous solution by advanced oxidation processes was studied. Advanced oxidation processes included ozone and its combination with H 2 O 2 and ultraviolet radiation (UV). Results demonstrated that UV alone was not sufficient to degrade cyanide ion but an oxidant was required for complete degradation. Degradation of 100 mg/L cyanide in aqueous solution was pseudo-first order reaction at pH 11.0. Lower pH was avoided due to formation of HCN gas but higher pH favoured the degradation. A comparison of three systems i.e. O 3 , O 3 /H 2 O 2 and UV/O 3 /H 2 O 2 showed that UV/O 3 /H 2 O 2 was the best system. The experimental results showed that the optimum conditions for UV/O 3 /H 2 O 2 process for total cyanide degradation were obtained at λ = 365 nm (400 W medium pressure UV lamp), ozone concentration = 35 mg/L and H 2 O 2 = 88.2 mM.