Electrochemical oxidation of crystal violet using a BDD anode with a solid polymer electrolyte

This paper explores the applicability of an innovative electrochemical cell with a solid polymer electrolyte (SPE) with mesh electrodes for the electrochemical oxidation of a low conductivity solution (0.022 mS/cm) containing crystal violet (CV) dye compound as model pollutant in a range concentration of 25-100 mg/L. The system anode/membrane/cathode is formed by Nafion membrane sandwiched between a Ti/RuO2 cathode and a BDD anode. The dependence of applied current, stirring rate, supporting electrolyte and temperature has been investigated. The experimental results showed that the electrochemical cell with SPE is suitable for the treatment of solution with a very low conductivity since the CV solution was completely mineralized with an energy consumption of about 60 kWh m(-3). Furthermore, the process was under charge transfer control for low applied current, becoming mass transfer control around 1 A. The addition of supporting electrolyte as Na2SO4 (0.6 and 1 g/L) and NaHCO3 (1 g/L) to the solution decreased the removal rate due to the presence of competitive reaction and scavengers media. The evolution of nitrogen compounds during the electrolysis shows that at the end of the process the 80% of initial N has been converted in nitrate and ammonium, indicating the formation of volatile compound.