Phenol Electrooxidation in Different Supporting Electrolytes Using Boron-Doped Diamond Anodes

In this work phenol was used as a model compound to study the influence of supporting electrolytes on the electrochemical oxidation of organic pollutants in aqueous medium, in absence and presence of chloride anions. The experiments were carried out in a flow electrochemical reactor using a boron-doped diamond (BDD) anode. The kinetics of chemical oxygen demand removal followed the pseudo-first order model, indicating that the process was mass transfer controlled. The supporting electrolytes containing nitrate and phosphate exhibited kinetics slower than those obtained using sulfate and carbonate. The addition of chloride greatly increases the process kinetics, especially at the very low pH provided by H2SO4 solutions. It was found that the electrooxidation kinetics, current efficiency and energy consumption are much more sensitive to the presence of chloride and the formation of oxidative chloro species than to supporting electrolytes through the formation of peroxysulfates or peroxycarbonates in the cases where sulfate and carbonate electrolytes were used.