Electrochemical degradation of the acid orange 10 dye on a Ti/SnO2 -Sb anode assessed by response surface methodology

Abstract

Aims: The aim of this study was decolorization of the synthetic aqueous solution of the acid orange 10 (AO10) dye on Ti/SnO 2 -Sb anode using the response surface methodology based on central composite design. Materials and Methods: The Ti/SnO 2 -Sb electrode was prepared using the standard thermal decomposition method and three variables: Current density (CD), pH, and supporting electrolyte concentration were assessed. The dye decoloration was monitored spectrophotometrically by measuring the absorbance of the remaining dye at the maximum absorption wavelength (λ max ) of 475 nm on a ultraviolet-visible spectrophotometer. To measure AO10 mineralization under optimum conditions, chemical oxygen demand (COD) and total organic carbon (TOC) removal also were evaluated. Results: It was found by the model prediction, minimum dye decolorization was 39% (CD = 6 and pH = 7.5) and maximum dye decolorization was 101% (CD = 65 and pH = 2). Thus, the optimum conditions for AO10 decolorization in synthetic dye solution were electrolyte concentration of 75 mM/L, pH of 2, and CD of 65 mA/cm. Under optimum conditions, decolorization of 100 mg/L dye was complete, and 61.3% and 43.9% COD and TOC removal were recorded after 50 min of electrolysis, respectively. Conclusion: High-efficiency electrochemical degradation of AO10 was achieved over Ti/SnO 2 -Sb anode as a model electrode. It was concluded that the most effective factor for AO10 decolorization was CD. The electrochemical degradation using Ti/SnO 2 -Sb electrode is a suitable and an environment-friendly method for the degradation of refractory dyes in aqueous solution.