Electrochemical incineration of p-cresol and o-cresol in the filter-press-type FM01-LC electrochemical cell using BDD electrodes in sulfate media at pH 0

This work shows a comparative study of the incineration of 2-mM p-cresol and o-cresol in 1M-H2SO4 in aqueous media. Microelectrolysis studies indicated that both the p-cresol and o-cresol oxidation were carried out via hydroxyl radicals (OH*) formed by water oxidation in the boron-doped diamonds (BDD)-H2O-H2SO4-p-cresol and o-cresol interface. In both cases, the potential and current density ranges, where great amounts of OH* are formed, were between 2.3 V <= E <= 2.75 V versus SHE and J=10 mA cm(-2). Electrolyses in an undivided FM01-LC reactor were performed at different Reynolds values 27,129 <= Re <= 42,631, and at J = 10 mA cm(-2). For p-cresol and o-cresol, the rate of degradation was slow, however it increases slightly as a function of the Re, indicating that the oxidation involves a complex pathway; current efficiency also rises as a function of the Re. For p-cresol, the mineralization at Re = 42,631 reached 90%, with 71% current efficiency and an energy consumption of 7.84 kWh m(-3); whereas o-cresol was mineralized to 84%, with 67% current efficiency and an energy consumption of 6.56 kWh m(-3), The results obtained in this work demonstrated that o-cresol is more recalcitrant than p-cresol. (c) 2006 Elsevier Ltd. All rights reserved.