| TiO2visible-light photocatalysis technology was used for degrading therefractory organic compounds in water, which has the characteristic of good Stableand efficient with low energy consumption. Thereinto, the modification of TiO2catalyst and concerted reaction is very important to the application of this technology.Therefore, in allusion to the insufficiency of existing research on visiblephotocatalysis, this paper is intended to prepare a kind of catalyst that had goodchemical stability and High catalytic activity, by means of researching the mechanismand process of TiO2visible photocatalysis with H2O2assistance. Then aphoto-electro-chemical catalytic reactor was designed to electro-generation ofhydrogen peroxide, which can be used in photocatalytic H2O2oxidation technology todeal with refractory organic matter.The degradation of prometryn by TiO2-P25visible-light photocatalysis withH2O2assiatance was studied. The results indicated that prometryn could be degradedby TiO2visible-light photocatalysis with H2O2assiatance, and the degradation ratiocould be80%after120min reaction. It was appropriate to control pH and the ratio of[H2O2]/[prometryn] to be3.0and45respectively, while the photocatalyst dosage tobe1.0g/L. In the degradation process of prometryn, methyl, thio and amino groupswere oxidized as NO3-and SO42-, the removal ratio of TOC reached70%, and the endproduct of prometryn degradation was cyanuric acid. Spectrum analysis indicated thatthe composite structures by H2O2adsorbing on the TiO2surface was converted to freeradicals under visible light, and the reaction process was predominated by thehydroxyl free radical (·OH) generation and superoxide radical (·O2-) in the system.In consideration of Fe3+with H2O2assistance has catalytic degradationperformance under visible light, Fe/TiO2photocatalysts were prepared by calcinationof mischcrystal TiO2and Fe(NO3)3·9H2O in air atmosphere, and the visible-lightphotocatalytic activity were also studied, which used prometryn as pollutants.Prometryn could be degraded with H2O2photocatalyzed by Fe/TiO2under visibleirradiation, the optimum iron ion content is0.5%, the degradation ratio could be99% after30minutes reaction, and the degradation efficiency was evidently better thanTiO-P25. Analyzed by the characterization methods of X-ray diffraction (XRD),scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS),specific surface area (BET) and so on, Fe/TiO2reflected iron element was in the formof Fe2O3, which could extend the range of light absorption and surface hydroxygroups. The composite photocatalyst keep a excellent stability and cycle performance,which was due to the synergistic effect of Fe3+, TiO2and H2O2.In order to solve the problem of H2O2utilization and improve the photocatalyticeffect, a photo-electro-chemical catalytic reactor was designed with net structureIr_Ta_Ti metal oxide coated titanium anode, platelike graphite cathode and saturatedcalomel reference electrode. Effects of electric current, oxygen flow andconcentration of supporting electrolyte (NaSO4) on electrogeneration of hydrogenperoxide was investigated. Then, the optimal combination of these factors wasproposed for Photo-electron-chemical catalytic degradation. The degradation effect ofprometryn by Fe-TiO2visible-light photocatalysis with electric current and oxygenflow assiatance was the best in different conditions, which the end product ofprometryn degradation was cyanuric acid after360min reaction, when the originalconcentration and volume of prometryn was9mg/L and450mL. The results fullyproved that photo-electron-chemical with Fe/TiO2catalytic had better applicationperformances than other advanced oxidation processes on sewage treatment. |
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