Photoelectrocatalytic Activity Of TiO₂ Using Microarc Oxidation

In this paper, filling with catalysis of particle electrode composed of three dimensional electrode system. TiO₂ was loaded with the GAC andγ-Al₂O₃ by sol-gel method, combining with regulated power supply make up the three-dimensional electrode photoelectrocatalysis system.Titanium oxide coatings (TiO₂/Ti) were formed on the titanium surface by micro-arc oxidation (MAO) in Na3PO4 solution with the concentration of 8g/L. And using the TiO₂/Ti as anod electrode( micro-arc oxidation time is 5min), the titanium as counter electrode in the system of three-dimensional electrode. The photoelectrocatalysis system use Na₂SO₄ aqueous solution as supporting electrolyte, and UV lamp (20W,λ=253.7nm) as the illuminant. The photoelectrocatalytic ability of titanium oxide coatings were evaluated by photoelectrocatalytic degradation of methylthionine chloride aqueous solution. In the sol-gel method, using tetrabutyl titanate as precursor, alcohol as solvent, and HCl as catalyst. After heat treatment, TiO₂/GAC and TiO₂/γ-Al₂O₃ were the loading-particle electrode.In this paper, there's some influence factors had been studied about photoelectrocatalysis degradation of methylthionine chloride simulate dye wastewater. Such as particle electrode calcining temperature, load membrane layer, particle ratio, power supply voltage, initial concentration of methylene blue solution, Na₂SO₄ electrolyte solution concentration, electrode gap and so on. There are the conclusions: (1)Under the best experiment condition, the system have the best efficiency, with the degradation of 75.32% after 3 hours. This three-dimension electrode system filling with GAC and the GAC /TiO₂ mixed particles have the high-efficiency degradation. System of main electrode TiO₂/Ti nets and GAC/TiO₂ electrodes all happened photocatalysis under the uv irradiation. TiO₂/GAC and GAC electrodes have the big adsorption property, and that increase the photocatalysis property, under the action of an external voltage, the system occurred electrochemical reactions.Moreover, doping rare-earth element to TiO₂/GAC can improve the photoelectrocatalysis activity for it's restrained the growing of crystalline grain. Experiments show that doped Eu catalytic having the best result.(2) Under the best experiment condition, the system have the best efficiency, with the degradation of 60.39% after 3 hours. This three-dimension electrode system filling with globular TiO₂/γ-Al₂O₃ and scrap iron mixed particles have the high-efficiency degradation. When the globular TiO₂/γ-Al₂O₃ and scrap iron particles as the third electrod, the reaction system of methylene blue degradation rates was promoted. The TiO₂/γ-Al₂O₃ particles have the photocatalytic activity, and then the photocatalytic activity increased obviously after mixed with scrap iron, And it acting as an insulator increase the scrap iron electrocatalysis role. Moreover, scrap iron within the role of electrolysis, and that generate Fenton reagents in the Fenton reaction. Further accelerate the speed of adsorption and degradation of organic pollutants.(3) Under the best experiment condition, the system have the best efficiency, with the degradation of 76.17% after 3 hours. This three-dimension electrode system filling with granule TiO₂/γ-Al₂O₃ and scrap iron mixed particles have the high-efficiency degradation. Comparing with the second system, filling material is extremely similar, reaction is also similar. The difference is the properties have been improved after crush about granule TiO₂/γ-Al₂O₃ and globular TiO₂/γ-Al₂O₃, And its size and scrap iron size similar, thus scrap iron and granule TiO₂/γ-Al₂O₃ particles fully mixing, so it improve the complex three-dimension electrode photoelectric catalytic efficiency.(4) Under the best experiment condition, the system have the best efficiency, with the degradation of 72.48% after 3 hours. This three-dimension electrode system filling with granule TiO₂/γ-Al₂O₃ and GAC mixed particles have the high-efficiency degradation. Particles mixing fully, polarity together constitute complex three-dimension electrode system. Thus forming photoelectric coordination reaction system, improve the system of three-dimension photoelectric catalytic efficiency.After the analysis of these systems, TiO₂ photoelectrocatalysis efficiency has improved obviously with the three-dimensional electrode. MAO-TiO₂/Ti and loading TiO₂ have the photocatalysis performance under the irradiation of UV, and the synergistic effect of them obviously. The three-dimensional electrode photoelectrocatalysis degradation of methylene blue increase thoroughly, comparing to traditional two-dimensional plate electrodes which without particle electrode.