Electrochemical oxidation treatment of Direct Red 23 aqueous solutions: Influence of the operating conditions

A comparative study of the degradation of Direct Red 23 (DR23) dye aqueous solutions by electrooxidation was investigated using different anodes: carbon graphite (CG), dimensionally stable anode (DSA), Magneli phase Ti4O7, and boron-doped diamond (BDD). Stainless steel (SS) and CG plates were tested as cathodes. The effect of operating parameters on the degradation kinetics of the dye was studied. In this study, NaCl and Na2SO4 were selected as supporting electrolytes; the former was found to be more suitable for the degradation of DR23. The degradation of the dye follows a pseudo-first-order kinetics in both media. Higher total organic carbon (TOC) efficiency was achieved by BDD/CG cells. Thus, the treatment efficiency obtained using a current density of 5 mA cm(-2), and DR23 concentration of 60 mg L-1 was about 86% using both NaCl and Na2SO4 electrolyte, at 6 h electrolysis time. The energy consumptions per g TOC removed were found to be 2.05 and 2.6 kWh g(-1) TOC in NaCl and Na2SO4 electrolytes, respectively.