Electrodeposition and Catalytic Performance of Hydrophobic PbO2 Electrode Modified by Surfactant OP-10

A hydrophobic PbO2 electrode modified by surfactant OP-10 was prepared by electrodeposition. The electrode has good hydrophobic surface (the hydrophobic angle can reach 123°), high over point oxygen evolution (OEP) (1.60 V vs. SCE), and good service life (81 h). The electrode morphology and electrodeposition mechanism study found that the addition of OP-10 can help to build a dense PbO2 electrode surface, reduce the occurrence of side reactions, and promote the positive deposition of PbO2. As much as 30 mg L-1 of methylene blue, as the simulated pollutant, could be degraded in 80 min under conditions of 50 mA cm-2, initial pH = 7, and a concentration of supporting electrolyte of 0.15 mol L-1, which could be easily reached. Moreover, a practical dye wastewater was employed, proving the OP-10 modified PbO2 electrode is suitable for industrial applications, where the COD of dye wastewater can be reduced from 330 to 4 mg L-1 in 120 min.

THE STUDY ON SOME PARAMETERS AFFECTING THE DEGRADATION OF METHYLENE BLUE IN WATER BY ELECTRO-FENTON USING TI/PBO2 ANODE

In this work, the combination of two advanced oxidation processes, electro-Fenton (hydroxyl radical ●OH generated by reactions on cathode) and anodic oxidation (●OH produced directly on anode), in the same reactor was studied to evaluate the treatment of methylene blue (MB) dye in aqueous solutions. This electrochemical system was equipped with a commercial carbon felt cathode (9.5cm 12cm), lead dioxide-coated titanium anode (10 12cm), direct current (DC) and continuously aerated. The effects of operating parameters such as pH, applied current (I), catalyst concentration ([Fe2+]) and MB concentration (C0) on MB removal efficiency were investigated through monitoring MB concentration at different times by spectrophotometric method. An optimal process was achieved at the condition of [Fe2+] = 0.1 mM; pH 3.0; [Na2SO4] = 0.05 M; i = 2.5 mA.cm-2 and after 60 minutes of electrolysis, 92.19% of MB was removed which was far higher than the figure obtained by using individually electro-Fenton (73.77%) or anodic oxidation (58.04%). These experimental results have demonstrated that the combination of electro-Fenton and anodic oxidation using Ti/PbO2 electrode is a prospective method for destruction of persistent dyes.

Optimization of Operating Conditions for Electrochemical Decolorization of Methylene Blue with Ti/α-PbO2/β-PbO2 Composite Electrode

α-PbO2 was introduced into the intermediate layer of an electrode to prevent the separation of the electrodeposited layer and maintain oxidizing power. The resulting Ti/α-PbO2/β-PbO2 composite electrode was applied to the electrochemical decolorization of methylene blue (MB) and the operating conditions for MB decolorization with the Ti/α-PbO2/β-PbO2 electrode were optimized. The morphology, structure, composition, and electrochemical performance of Ti/α-PbO2 and Ti/α-PbO2/β-PbO2 anode were evaluated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The optimum operating parameters for the electrochemical decolorization of MB at Ti/α-PbO2/β-PbO2 composites were as follows: Na2SO4 electrolyte 0.05 g L−1, initial concentration of MB 9 mg L−1, cell voltage 20 V, current density 0.05–0.10 A cm−2, and pH 6.0. MB dye could be completely decolorized with Ti/α-PbO2/β-PbO2 for the treatment time of less than one hour, and the dye decolorization efficiency with Ti/α-PbO2/β-PbO2 was about 5 times better, compared with those obtained with Ti/α-PbO2.