Investigation on electro-catalytic oxidation properties of carbon nanotube–Ce-modified PbO2 electrode and its application for degradation of m-nitrophenol

Abstract

In this work a carbon nanotube–Ce-modified PbO2 (CNT–Ce–PbO2) electrode was prepared by electrodeposition method, and compared with pure PbO2, Ce–PbO2, and CNT–PbO2 electrodes. The direct and indirect oxidation capacities of prepared electrodes in electro-catalytic oxidation processes were investigated by cyclic voltammetry and hydroxyl radical production tests, respectively. The electro-catalytic activity of electrodes was examined by electro-catalytic oxidation of a model pollutant of m-nitrophenol (m-NP). Besides, high-performance liquid chromatography (HPLC) was also employed to identify the products resulting from the electro-catalytic oxidation of m-NP and the degradation mechanism of m-NP was proposed. Results show that the CNT–Ce–PbO2 anode has higher direct and indirect oxidation capacities than pure PbO2, Ce–PbO2, and CNT–PbO2 anodes. In the electro-catalytic oxidation of m-NP, the m-NP can be oxidized and degraded at all anodes, and the oxidation reactions of m-NP follow first-order kinetics. m-NP and TOC removal efficiencies are about 0.987 and 0.622 after electrolysis of 120 min and a maximum first-order rate constant of 0.036 min−1 is achieved at the CNT–Ce–PbO2 anode, which are obviously higher than those of the other three kinds of anodes. Keywords: Electro-catalytic oxidation, PbO2 electrode, Carbon nanotube, Ce, m-Nitrophenol