Electrooxidation of 2,4-dichlorophenol and other polychlorinated phenols at a glassy carbon electrode

The electrooxidation of 2,4-dichlorophenol (2,4-DCP) on a rotating GC disk electrode has been studied by cyclic voltammetry and chronoamperometry at different pH values. A dual mechanism where one pathway yields a quinone-like species and the other one leads to insoluble polymers that passivate the electrode surface is proposed. From a comparative study of the electrooxidation of several DCPs at pH 2.2, it is concluded that for the same number of chlorine atoms the ortho isomer is oxidized at a lower potential than the para isomer. The anodic peak potential for electrooxidation of the chlorophenols (CPs) on glassy carbon increases with increasing pK(a), with a slope of 35 mV (pK(a) unit)(-1), illustrating the correlation of one chemical parameter of the CPs, namely their acidity constant, with their electrochemical reactivity. (C) 2002 Elsevier Science Ltd. All rights reserved.