Development of a rate expression for predicting decolorization of C.I. Acid Black 1 in a UV/H2O2 process

A kinetic rate expression was developed by the experimental results of photochemical reactions that decolorize model azo dye, C.I. Acid Black 1. The decolorization was efficient by UV irradiation with hydrogen peroxide addition. The observed reaction rate constants were determined and correlated as a function of volumetric UV dosage and initial hydrogen peroxide concentration. The decolorization rate follows pseudo-first order kinetic with respect to dye concentration. The rate increases linearly by volumetric UV dosage, yet nonlinearly by hydrogen peroxide concentration. The proposed rate expression model, which considers both the kinetic mechanism and operation parameters, can predict the experimental results well. The prediction and experimental data are in a very good agreement. Besides, this model also integrates the correlation of pH and initial dye concentration in order to enlarge more versatile applications while various dye concentrations and pH range in the real case.