Electrocatalytic oxidation of phenol was investigated in the presence of a series of composite metal oxides supported on γ-Al₂O₃ as particle electrodes. These particle electrodes were prepared by sol-gel method. Morphologies and microstructures were characterized by BET surface area, scanning electron microscope and X-ray diffraction. Mn-Sn-Sb (2∶1)/γ-Al₂O₃, which had a molar ratio of Mn to Sn of 2∶1 and 0.1 wt% Sb, was found to have the highest electrocatalytic activity. It was observed that both disappearance of phenol and loss of total organic carbon (TOC) obtained for the Mn-Sn-Sb (2∶1)/γ-Al₂O₃ were significantly more efficient than that obtained with the Ru/TiO₂ particle electrode used as reference. In addition, Mn-Sn-Sb (2∶1)/γ-Al₂O₃ particle-electrode was found to be active even after the particle electrode was reused five times, indicating high stability with the particle electrode. The causes for the deactivation of particle electrodes were discussed, and were related to the dissolution of the active ingredients from the catalyst surface as well as polymeric deposits on the catalyst surface.

Key words: electrocatalytic oxidation, particle electrode, wastewater treatment, phenol