Performance enhancement and optimization of photocatalytic cyanide degradation in aqueous solution using Zn (II) and Fe (III) oxides as nanostructure supported on activated carbon

Abstract

BACKGROUND: Cyanide is a toxic compound used in gold mining, steel, electroplating and chemical industries. In this research, different mole ratios of Fe3+/ZnO supported on powder activated carbon (PAC) in the presence of H2O2 under UV irradiation were used to degrade cyanide contamination. The photocatalyst was characterized by XRD, XRF, FESEM, TEM and BET and response surface methodology was applied to assess the individual and interaction effects of several operating factors on cyanide degradation efficiency and to determine the optimization conditions. RESULTS: The results indicated that the average particle size of catalyst ranged from 20 to 60 nm. pH had the largest effect on response and there was interaction between initial cyanide concentration and pH. Decreasing the initial cyanide concentration and pH, while increasing the catalyst dosage, hydrogen peroxide concentration and irradiation time improved the cyanide degradation efficiency. The experimental result of cyanide degradation efficiency under optimum conditions ([CN]− = 250 mg L−1, photocatalyst = 1.4 g L−1, irradiation time = 180 min, pH=10, mole ratio of Fe3+/ZnO=6% and [H2O2] = 300 mg L−1) was about 98%. Photocatalytic activity was maintained even after seven successive cycles. CONCLUSION: The synthesized reusable high activity nanostructure photocatalyst can be considered an applicable and environmentally friendly catalyst for the decontamination of cyanide-polluted water. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry