Study On Photocatalysis Oxidation Degradation Of Acid Blue Dye Wastewater With Magnetic Field

In recent years, photocatalytic degradation of high concentration and difficultbiochemical organic wastewater with semiconductor has got very great development,but still it is insufficient to exist, for example, pured TiO₂ photo-generating carrierrecombination rate is high and energy efficiency is low. In order to improving thequantum efficiency of photocatalysis and energy utilization, accelerating the interfacemobility of photo-generating carrier and reducing its recombination rates, we tookparamagnetic semiconductor microcrystalline Fe₂O₃ as active component, appliedmagnetic field and a certain wavelength common incandescent lamp light cooperativephotocatalytic degradation of acid blue dye wastewater in this paper.Based on the concentration of acid blue dye wastewater, 1000 mg/L, COD1640 mg/L and used the process of H₂O₂ catalytic oxidation, preparation of catalyst,conditions of treating wastewater, the combined cooperative effect of magneto-opticaland mechanism of dye degradation were studied in this paper.In the process of catalyst development, the selection of supports, concentrationof soaked liquid, impregnating time and frequency, calcination conditions and theservice life of catalyst were discussed. The results showed the catalyst suppored onultrafine amorphous SiO₂ had high catalytic activity. The support was impregnated inferric nitrate solution, the concentration of 0.4 mol/L, for once 5 hours and calcined at500℃for 3h COD removal of 81.71% were obtained over the catalyst in thetreatment of acid blue dye wastewater. The COD removal still kept 80.98% and thecatalyst remained high catalytic activity after reuse of 5 times. The results showed thecatalyst represented a better activity and longer service life. The crystal phase ofcatalyst isγ-Fe₂O₃/SiO₂ by analysis of IR and XRD.In the research of wastewater treatment technology, the effects of pH, catalystdosage, H₂O₂ amount, reaction time and reaction temperature on the efficiency oftreating acid blue dye wastewater were discussed. The experimental results showedthat the COD removal rate can reach 81.71% under the conditions of pH 3, catalyst dosage 1.6 g/L, H₂O₂ amount 6 mL/L, reaction temperature 70℃and reaction time120 min.In the research of the combined cooperative effect of magneto-optical, theeffects of applied single incandescent lamp, magnetic field and cooperative effect ofmagneto-optical on the efficiency of treating acid blue dye wastewater were discussed.The results showed that all of the three factors had influence on the COD removalrate of photocatalytic treating acid blue dye wastewater. The COD removal rateincreased from 81.71% to 86.83% under the conditions of illumination intensity 11w,light source distance 15 cm and illumination time 120 min. The COD removal rateincreased from 81.59% to 85.12% under the conditions of intense of magnetic field2.2 mT and imposing time 100 min. The COD removal rate could reach 87.71%under the constant above conditions and magneto-optical cooperative acting time 100min.In order to better control reaction process conditions and master the reactionrules, the mechanism of dye degradation was preliminarily studied in this paper. Inthe process of photocatalytic oxidation acid blue, First·OH attacked the azo bond andsimultaneous partially substituted for -SO₃Na. After the abscission of azo bond, aseries of unstable intermediates were generated. With the reaction progressing, thoseintermediates were became some of small molecular acid and even mineralized toCO₂ and H₂O in the presence of·OH and O₂.