Study On Three Dimensional Mesh TiO₂ Photoelectrocatalytic System And Theremoval Of Perchlorate In Water

Perchlorate has certain potential toxicity, it has a greater impact on the organism and can be long-term stability in water. With the development of the society, perchlorate pollution has been neglected in the production and living. As perchlorate is difficult to reduction in the normal condition and the common physical and chemical method and biological method can be used to deal with it simply, in addition, each of them have different disadvantages, so they are not conducive to promote. Recently, Ti O2 is concerned as a new type of catalyst and its excellent light response performance makes photoelectrocatalytic degradation perchlorate in water become the most effective method at present.This paper took the characteristics of nano Ti O2 catalyst as the research object and established a method for photoelectrocatalytic reduction perchlorate by nano Ti O2 catalyst. The preparation of nano Ti O2 catalyst was studied, and the reaction system of photoelectrocatalytic degradation was constructed. By optimizing the orthogonal experimental conditions, with 0.3 wt% NH4 F and 2% H2 O in the ethylene glycol electrolyte and external 60 V voltage anodic oxidation processing 40 min, then calcination processing 2 h at the 550 ℃ in the muffle furnace can get bilayer nano Ti O2 catalyst(upper layer film, lower layer nanotube). Using the precursor solution of 10 mmol/L Ag NO3 to load and with high temperature calcination 2 h at the 500 ℃ to produce. The modified catalyst can be proved that it is stable and efficient catalytic activity after many repeated experiments.Combined the Langmuir-Hinshelwood dynamic model with the volume energy absorption rate formula of double flux model, a certain space structure of titanium mesh nano Ti O2 catalyst was produced. Results indicate that the law of catalytic degradation is basically consistent with the law of the light induced voltage, and when the titanium mesh with the catalyst layer is folded into three layers in a certain space configuration, the light induced voltage is the largest and the catalytic ability is also the strongest.This paper examines the effects of various factors on the perchlorate by photoelectrocatalytic reduction, it promotes the reaction in the lower initial concentration and lower initial p H and the reaction rate of photoelectrocatalytic reduction of electric perchlorate in water meets three order kinetic equation. With the increase of the number of titanium mesh layers and the increase of the area, the light utilization efficiency can be improved, and the active sites of the catalyst can be increased. With the increase of the applied bias voltage, perchlorate removal rate also increased. Finally in the use of the initial concentration of 10-6 mol/L sodium perchlorate, 0.15 mmol/L citric acid as reaction liquid and adjust the initial p H value is about 3.6, the Ti O2 catalyst loaded with Ag as photoelectrocatalytic electrode and under the 1.5 V applied voltage value to react for 6 h, then the perchlorate removal rate reached more than 60%.This paper examines the effects of electrolysis and photolysis reduction on the perchlorate. The experiment of photocatalytic reduction results show that the effect of electrically assisted photocatalytic reduction is not the simple addition of photocatalytic reduction and electrocatalytic reduction. Under the action of the applied voltage, the system of perchlorate catalytic degradation efficiency and action rate increased nearly one times, it provided a feasible method for electrically assisted photocatalytic reduction of perchlorate in water. Combined with Cyclic Voltammograms, Electrochemical Impedance Spectroscopy and Mott-Schottky equation, identified that the Photocatalytic Reduction reaction play a leading role in the electrically assisted photocatalytic reduction of perchlorate in the reaction system. And the applied voltage only appropriate to improve the space charge layer band bending in a certain extent,and improve photoelectron generation and the migration and transformation ability of it. Electrocatalysis do not directly involve in the catalytic reduction reaction.