EFFECT OF ANODIC AND CATHODIC REACTIONS ON OXIDATIVE DEGRADATION OF PHENOL IN AN UNDIVIDED BIPOLAR ELECTROLYZER

Abstract

Both anodic oxidation and generation of hydrogen peroxide through electroreduction of oxygen may be useful for oxidative degradation of organic compounds. To clarify the effect of electrode reactions of both sides of a bipolar plate on the current efficiency for oxidative degradation of phenol, experiments were conducted by using an undivided bipolar electrolyzer having a vertical stack of perforated graphite electrodes. The Faradaic current I_f was arranged as a function of the electrode potential difference E_B between opposite sides of a bipolar plate. By analyzing the I_f - E_B curves for the electrolyses in solutions containing different reactants, separate currents corresponding to anodic and cathodic reactions were determined. The effect of E_B on the COD current efficiency Ce(COD) for the oxidative degradation of phenol could be well explained by the contribution of the currents of phenol oxidation and oxygen reduction to the total current. The value of Ce(COD) in case of sparging oxygen showed a bimodal curve having the maximum values with respect to E_B.