Modeling and optimization of acid chrome dark blue degradation by Fenton using Box-Behnken Response Surface Methodology

This work investigated effects of some operational conditions on acid chrome dark blue degradation by Fenton, such as pH, FeSO₄ and H₂O₂ doses. The optimization parameters was proposed using Box-Behnken Response Surface Methodology. The degradation velocity was increased with FeSO₄ dosage increasing. But it mounted slowly at the 5ml of FeSO₄ dose. Because the FeSO₄ reached to a certain extent, H₂O₂ became the limiting factor. For H₂O$ dose higher than 0.4ml, no further increase in the decolorization rate was observed. The pH effect was found for the Fenton process. When pH was 2, the decolorization rate was 98.5% at the reaction time of 30 min. However, pH was 4 and 5, the decolorization rate was only 88.1% and 80.6% at 30min. The three-factor and three-level Box-Behnken was utilized for mathematical modeling for decolorization rate as a response by Fenton. The dosage of FeSO₄ and H₂O₂, reaction time, the interaction of FeSO₄ dose and reaction time were significant factors. The determinate coefficient of model was 0.9915. The optimum three operating conditions were that the FeSO₄ dose was 3.68ml, H₂O₂ dose was 0.30ml and reaction time was 15min. Under such conditions, the error of the model predicted and experimental value was 0.95%. It indicated that the Box-Behnken RSM was effective and reliable for optimizing the degradation process of acid chrome dark blue by Fenton.