Electrocatalytic oxidation is a promising process for degradation of toxic and biorefractory organic pollutants in wastewater treatment. Selection of electrode materials is crucial for electrocatalytic degradation process [1, 2]. The development of PbO2 anodes for the degradation and oxidation of organics has been gained great interest in environmental applications because of their good conductivity and large over-potential for oxygen evolution in acidic media, which enabling the production of hydroxyl radicals during water discharge [3, 4]. This work has investigated the electrocatalytic degradation of malachite green (MG) dye in aqueous solution with stainless steel/PbO2 electrode. The novel PbO2 electrode presented high stability, safety, oxygen evolution over potential and degradation efficiency for organic pollutants [5]. The surface morphology and crystal structure of the electrodes were characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD) respectively. Besides, the optimal degradation conditions were obtained by studying the effecting of different parameters, such as current densities (2-10 mA cm-2), electrolysis time (1-50 min), initial pH (2-12) and initial MG concentrations (360-720 mgL-1). The results of these factors are expressed in term of the remaining organic compounds concentrations (color removal) and chemical oxygen demand (COD removal). The results indicated that the color removal rates of MG reached up to 99% and COD removal up to 95% after 40 min electrolysis at initial 360 mg L-1 MG dye at constant current density of 10 mA cm-2 and energy consumption of 1.25 KWh Kg-1 COD, respectively. In addition, cyclic voltammetry tests showed that the degradation of MG was mainly achieved via indirect electrocatalytic oxidation mediated by hydroxyl radical.
