Nonlinear regression analysis of kinetics of the photocatalytic decolorization of an azodye in aqueous TiO2 slurry

Abstract

The kinetics of decolorization of an anionic monoazo dye of acid class named C.I. Acid Red 27 (AR27) was investigated in the UV/TiO₂ process with nonlinear regression analysis. The experimental results indicated that the kinetics of decolorization of AR27 in this process fit well by pseudo-first order kinetics. With nonlinear regression analysis a model was developed for pseudo-first order rate constant (k_ap,UV/TiO2) as a function of operational parameters such as TiO₂ dosage, initial concentration of AR27, concentration of O₂ and UV-light intensity (I₀) as following: k_ap,UV/TiO2 = 0.0025 [TiO₂]^0.65 [AR27]₀^−0.96 [O₂]^0.16I₀. This rate expression can be used for predicting k_ap,UV/TiO2 at different conditions.