Electrochemical degradation of Acid Orange II dye with boron-doped diamond electrode: Role of operating parameters in the absence and in the presence of NaCl

• The degradation of Acid Orange II on boron-doped diamond was optimized by factorial design methodology.
• Mixture of sulfate and chloride was employed as supporting electrolyte.
• Increasing sulfate concentration will decrease the removal efficiency of AO II.
• Chloride plays interesting and important roles in BDD technology.

This work shows results obtained in the electrochemical degradation of 50 mg dm−3 Acid Orange II dye in the presence of different supporting electrolytes (sulfate, chloride, and their mixture of different proportion). Experiments have been performed with a batch recirculation cell containing boron-doped diamond anode and Pt cathode. The effect of operating parameters, such as treatment time (20–40 min), flow rate (400–600 ml min−1), applied current density (1.29–2.58 mA cm−2) and total concentration of supporting electrolytes (1.0–5.0 mM), on treatment performance is assessed implementing a factorial experimental design. The results obtained, demonstrate that chlorides play interesting and important roles during the electrolytic oxidations. Additionally, the evidences from UV–vis spectra are used to better clarify the different roles of operating variables recorded.