Using BoxâBehnken experimental design to optimize the degradation of Basic Blue 41 dye by Fenton reaction

Abstract

Degradation of a Basic Blue 41 dye using Fenton reagent was examined at laboratory scale in batch experiments using BoxâBehnken statistical experiment design. Dyestuff, hydrogen peroxide (H₂O₂) and ferrous ion (Fe²⁺) concentrations were selected as independent factors. On the other hand, color and chemical oxygen demand (COD) removal were considered as the response functions. The value of coefficient of determination (R²) for both color and chemical oxygen demand removal with values 0.98 and 0.99 shows the best agreement between predicted value and experimental values. Perturbation plots indicated that iron dosage has the most effect on both color and COD removal. Normalized plot of residuals also indicated that the models were adequate to predict for both responses. Color and COD removal increased with increasing H₂O₂ and Fe²⁺ concentrations up to a certain level. High concentrations of H₂O₂ and Fe²⁺ did not result in better removal of color and COD due to hydroxyl radical being gradually consumed by both oxidant and catalyst. Percent color removal was higher than COD removal indicating the production of colorless compounds. The second-order polynomial model revealed optimal process factor ratio. The ratio of H₂O₂/Fe²⁺/dyestuff which gives a complete color removal and 95% COD removal was found to be 1195 mg/L/90 mg/L/255 mg/L.