Abstract:
Cyanide is a highly toxic substance and most found in metal plating industrial wastewater. Oxidation technique is generally applied for cyanide treatment technologies. This research is investigated the effect of zinc on cyanide removal by ferrate oxidation. The first experiment was done on the synthetic wastewater that the maximum concentration of cyanide is 500 microM. It is to study the effect of pH and the increased mole fractions of ferrate per cyanide to both of by products and cyanide removal efficiency. The result, at the mole fraction of 1:1 ferrate per cyanide, approximately 85-100% of cyanide removal efficiency was found at pH 9, 10 and 11 with the fast rate at pH 9. The increasing initial concentration of cyanide in each reaction caused the trend of increasing cyanide removal efficiency. Cyanate was identified as the major product of the reaction. The second experiment was conducted on 150 microM. of zinc at pH 9 and 200 microM. of zinc at pH 10 and 11 that considered as saturated concentration of zinc. It is to study the effect of zinc to cyanide removal efficiency, mole fraction of ferrate per cyanide during the reaction rate and the chemical reaction rate. The results indicated that zinc has no effect on both cyanide removal efficiency and any mole fractions of ferrate per cyanide, but it retarded the chemical reaction rate. The ferrate molar consumption per oxidized cyanide was 0.88:1. The final experiment was done on the wastewater that collected from a zinc plating industry. The total cyanide of the sample was 108,622 microM. The experiment was done on 104.78 microM. of total cyanide by dilution. The result show 100% of the total cyanide was removed. The mole fraction of ferrate consumption per oxidized cyanide was 1.37:1. The mole fraction is 1.57 time of the result in the experiment with synthetic wastewater that maybe the effect of the many substance in the wastewater