Determination of thiocyanate in the vacuum carbonate desulfurization wastewater

In acidic solution, thiocyanate molecules reacted with ferric ions to produce red complexes. The concentration of thiocyanate could be determined by spectrophotometer. The effects of wavelength, volume of color reagent, acidity and color time on absorbance were investigated. The interferences of co-existing ion were discussed as well. Results showed that the relation between absorbance and the concentration of thiocyanate was in accord with Beer's law when the concentration of thiocyanate was 2-20 mg/L. The linear regression equation was Absorbance = 0.0523Concentration-0.0156, with a linear correlation coefficient of 0.9997. The average recovery rates of two kinds of vacuum carbonate desulfurization wastewater were 100.95% and 99.62%, and relative standard deviations were 0.79% and 0.14% respectively. It shows that the method was quick, high precision, accurate and easy to handle.