Optimization and Kinetic Model Development for Photocatalytic Dye Degradation

Abstract

In this study, the carbon-doped zirconium dioxide ( $$\hbox {ZrO}_{2}$$ –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, $$\hbox {ZrO}_{2}$$ –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 $$= 18\,\hbox {W}$$ 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 reactions was 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%).