Electrochemical degradation of reactive brilliant red X-3B with the (CeO2/C)-β-PbO2-PTFE composite electrode

Abstract

The (CeO2/C)-β-PbO2-PTFE composite electrodes modified by graphite powder, cerium oxide powder, polytetrafluoroethylene (PTFE) and the homemade β-PbO2 powder were prepared by the high pressure molding technique. The X-ray diffraction (XRD) was used to test the purity of the homemade β-PbO2 powder. The surface structure and electrical property of electrodes were characterized by using scanning electron microscopy (SEM) and the cyclic voltammetry curves (CV). Those images indicated that in electrolysis the (CeO2/C)-β-PbO2-PTFE composite electrodes had higher activity than the β-PbO2-PTFE electrodes, as good as the excellent catalytic performance. In the electrode system the composite electrodes were applied to treat reactive brilliant red (RBR) X-3B solution and we studied the degradation influence factors and the reaction mechanism. The results showed that the electrode system was well in treating RBR X-3B solution with the 20%(CeO2/C)-β-PbO2-PTFE composite electrodes at the initial 100 mg/L RBR X-3B concentration, Na2SO4 concentration of 0.35 mol/L, the constant current density of 30 mA/cm2 and electrolyte pH=2. After electrolytic time of 90 min, the maximum decolorization and chemical oxygen demand (COD) removal rates reached 88.92% and 54.54%. And the decolorization rate of RBR X-3B was in conformity with pseudo-first-order kinetics equation. The RBR X-3B degradation mechanism in the electrochemical oxidation system was used with LC-MS to analyze the possible intermediates and degradation pathway.