| In the twenty-first century, with the rapid development of the world industry and agriculture, the problem of water pollution has attracted wide attention. As the first of four major water pollution sources, organic pollutants treatment has been appreciated widely. Large amounts of toxic biodegradable organic pollutants have been a serious threat to human survival environment. The lack of effective purification and treatment has become a major problem in the field of water treatment and the "bottleneck" affecting the global social and economic development. Electrochemical oxidation treatment of organic wastewater has become a relatively mature advanced oxidation technology in recent years. It is a degradation of organic matter in wastewater that directly by the electrode reaction, or generated by the electrode reaction of·OH, O3with strong oxidizing intermediates in the electrochemical reaction system. Lead dioxide (PbO2) electrode has many excellent properties, including high oxygen evolution potential, good stability, corrosion resistance, and it has being widely used in the electrochemical oxidation treatment of organic contaminated wastewater. During the study on PbO2electrode, it has improved and promoted substrate, intermediate layer and PbO2surface active substances in many ways, and gradually developed a titanium (Ti) base PbO2electrode (DSA) as the new representative of the PbO2electrode. This electrode has good electro-catalytic activity, but the passivation of Ti-base can result in PbO2coating off with long time electrolysis and the Ti substrate is difficult to widely used in industrial production because of the high cost and short life. Therefore, the development of new PbO2electrode is an important topic. And aluminum (Al) causes for concern due to its excellent properties, such as low density, plastic, electrical conductivity, thermal conductivity, corrosion resistance, easy recovery, easy surface modification.Three aspects of research was carried out in this paper:1)Make use of electro-deposition on the Al matrix prepared PbO2electrode, the use of surfactants and polyethylene glycol (PEG) with different amounts of PbO2coating modified, and scanning electron microscopy(SEM) analysis of the morphology of the surface of the coating structure, meanwhile take advantage of the polarization curves visits coating oxygen evolution potential, Tafel curve method, electrochemical impedance spectroscopy, scanning electrochemical microscopy method investigated plating electro-catalytic performance, corrosion resistance and other electrical chemical properties.2) Focus on the PbO2electrode modified by electrochemical oxidation degradation of methyl orange dye wastewater bleaching, wastewater pH, the amount of electrolyte, current density, temperature and other factors investigated the preparation of PEG-modified PbO2electrode of methyl orange degradation of dye wastewater decolorization. Explore the optimal process parameters, the macro-dynamics of methyl orange decolorization.3) Study on the PbO2electrode catalytic oxidation mechanism of degradation of methyl orange dye wastewater through the usage of the cyclic voltammetry test.Through this research, the conclusions are as follows:1) The appropriate addition level of PEG in bath is6g·L-1when take the electrodeposition preparation of PEG modified for PbO2electrodes. The PbO2coating under this added amount has good electrochemical performance with lots of advantages, such as tiny densified grain on its surface, analysis high oxygen potential, electro-catalytic performance and good resistance to corrosion.2) The oxygen evolution potential of the prepared modified PbO2electrode under acidic conditions is higher than under alkaline conditions, while the electro-catalytic activity is better. The optimal process conditions for degradation decolorizing the methyl orange dye wastewater drew by orthogonal test are the current density of50mA·cm-2, pH value of6, temperature25℃, and the amount of electrolyte Na2SO44g·L-1.Under the optimal process parameters, this study explore the macro-dynamics of methyl orange decolorization and conclude that degradation decolorizing of methyl orange conform to the first order reaction and its kinetic model equation is the methyl orange concentration C=23.99e-0.077.3) PbO2degradation of methyl orange dye wastewater is an oxidation reaction involved adsorption, diffusion and subsequent chemical conversion. First is the water molecules on PbO2electrode surface adsorbed-OH, reaction:PbO2+H2O→PbO2(·OH)+H++e-. As the continuous positive shift of the electrode potential, methyl orange in the PbO2electrode firstly occurred the bleaching reaction, generating the n, n-dimethyl-p-phenylenediamine, and then further generated N,N-dimethyl quinonediimine through the oxidation reaction, that is an oxidation peak produced by the cyclic.voltammetry. At last the final product came up with degradation reaction between N, N-dimethyl-quinone diimine and·OH.The project funded by the National Fund. |
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