Modeling and optimizing of electrochemical oxidation of C.I. Reactive Orange 7 on the Ti/Sb–SnO2 as anode via response surface methodology

Abstract

The decolorization and degradation of an organic dye, Reactive Orange 7 (RO7) in aqueous media by electrochemical oxidation process using Ti/Sb–SnO2 electrode as anode was modeled and optimized using response surface methodology (RSM) based on central composite design (CCD). The anode electrode was prepared using dip-coating and thermal decomposition method. Accordingly reduced quadratic model was developed to give the substrate color removal efficiency percentage as function of effective parameters such as: initial dye concentration, pH of the solution, electrolyte concentration and current density. The fit of the model is checked by the determination coefficient (R2). In this case, the value of the determination coefficient (R2=0.9949) is indicated. Maximum color removal efficiency was achieved at the obtained conditions of: pH=4, concentration of electrolyte=3.5g/L and current density=19mA/cm2. Dye removal rate increased by increasing the concentration of electrolyte, lowering pH and increasing the current density. In optimum conditions, decolorization was obtained completely after 5min; and the removal of chemical oxygen demand (COD) was reduced to 70.3% after 90min.