Auto-inhibition effects in anodic oxidation of phenols for electrochemical waste-water purification

Abstract

Removal or modification of noxious organic impurities in waste-waters is a major challenge for environmental science. Pollutants such as phenols and their derivatives, as well as PCBs, have attracted special attention. In recent years, the possibilities of effecting direct electrocatalytic oxidations at high-area electrodes such as supported Pt or RuO2 have been investigated. However, in a number of cases, especially with phenolic impurities, application of anodic oxidation fails to lead to continuous Faradaic oxidation currents owing to the electrode surfaces becoming blocked with polymeric oxidation products leading to auto-inhibition ("passivation") of the desired electrode process. Examples of such effects with phenols and related compounds are examined comparatively in the present paper by means of cyclic volatammetry and chronoamperometry.