Optimization and Kinetic Model Development for Photocatalytic Dye Degradation

In this study, the carbon-doped zirconium dioxide (ZrO2-C) nanocatalyst was synthesized by sol-gel method and was used for the degradation of basic red 46 (BR46) in water. In order to optimize the dye removal efficiency, different experimental variables involving pH, ZrO2-C concentration, initial BR46 concentration, and light intensity were analyzed by the response surface methodology. Variance analysis showed high determination coefficient values, with R-2 and adjusted-R-2 of, respectively, 0.9984 and 0.9965, as well as, a satisfactory prediction of the second-order regression model. Optimization results showed a maximum color removal efficiency of 98.4% at the optimal condition with initial pH 11, ZrO2-C concentration = 0.15 g/L, UV light intensity = 18 W and the initial dye concentration = 5 mg/L. Finally, a new kinetic model, in the form of Langmuir-Hinshelwood equation, based on the intrinsic element reactionswas developed. The results indicated that the developed DDR-II model fitted well with the experimental data and with a minimal value of the mean absolute relative residual (13.08%).