Investigation On Preparation Of Several Kinds Of Ferrites And Their Microwave Induced Catalytic Activity

Dye wastewater is one of the main sources of water pollution in our country.When Dye wastewater released into the water, it have chemical stability and makeprone to eutrophication. So it is a typical refractory organic pollutants. Dyewastewater treatment is a research hotspots and the difficulty in the environment field.In recent years, microwave catalytic technology is widely used in the dye wastewatertreatment. At present, the sensitizing agent of the microwave catalytic oxidationtechnology has become the research hotspot in microwave field. The experiments ofpreparation, degradation, modification and microwave catalytic activity were carriedout to study the degradation of acid red B （AR-B）, as a model organic contaminant,under microwave irradiation catalyzed by ferrite.In the first chapter, zinc ferrite （ZnFe₂O₄） was prepared by chemicalprecipitation method. The optimum preparation conditions was explored in mass ratioof Zn²⁺: Fe²⁺: C2O₄^-, the heat-treated time and the heat-treated temperature. Thecatalytic activity of ZnFe₂O₄was studied under microwave radiation. The degradationratio of acid red B could reach70.0%for25mL solution with10mg/L parathionunder6.0g/L catalyst,600W and3.0min MW irradiation. Under the sameconditions, acid red B could be degraded at78.0%by prolonging irradiation time at5.0min. Also, the influences of the initial concentration of acid red B, additionamount of catalyst, MW power as well as MW irradiation time on the degradationwere discussed adopting UV-vis spectra, ion chromatography and liquidchromatography technologies. These results show that the acid red B could bedegraded rapidly under microwave irradiation catalyzed by ZnFe₂O₄. The methodusing ZnFe₂O₄/MW technologies showed many advantages including nointermediates and no secondary pollution. It is a promising technology for thetreatment of dye wastewaters.In the second chapter, ZnFe₂O₄loaded activated carbon （ZnFe₂O₄/AC） wasprepared by calcination method. The catalytic activity of ZnFe₂O₄/AC was studiedunder microwave irradiation. The catalytic activity of ZnFe₂O₄/AC was the best when ZnFe₂O₄load ratio was3:10. The degradation ratio of acid red B could reach75.7%for50mL solution with50mg/L acid red B under0.3g/L catalyst,450W and1.0min MW irradiation. Under the same conditions, acid red B could be degraded at86.6%by prolonging irradiation time at3.0min. And the same conditions using pureAC as catalyst, the degradation rate were70.8%and78.0%respectively. Also, theinfluences of the initial concentration of acid red B, addition amount of catalyst, MWpower as well as MW irradiation time on the degradation were discussed adoptingUV-vis spectra, ion chromatography and liquid chromatography technologies. Theseresults show that ZnFe₂O₄/AC as catalyst can rapidly degrade acid red B undermicrowave irradiation. The catalytic activity of ZnFe₂O₄/AC was better than pure AC.In the third chapter, the three kinds of ferrite （ZnFe₂O₄MgFe₂O₄MnFe₂O₄）were prepared. The effects of the heat-treated time and the heat-treated temperatureon the catalytic activity were assessed. And the microwave catalytic activity of threekinds of catalyst was compared. The degradation ratio of acid red B could reach67.2%，100%and29.6%, respectively, using three kinds of ferrite （ZnFe₂O₄MgFe₂O₄MnFe₂O₄） for25mL solution with10mg/L acid red B under8.0g/Lcatalyst,600W and3.0min MW irradiation. Also, the influences of the initialconcentration of acid red B, addition amount of catalyst, MW power as well as MWirradiation time on the degradation were discussed adopting UV-vis spectra, ionchromatography and liquid chromatography technologies. These results show thatZnFe₂O₄, MgFe₂O₄and MnFe₂O₄have certain catalytic activity under microwaveirradiation. MgFe₂O₄of catalytic activity was best than that of ZnFe₂O₄andMnFe₂O₄.In summary, the method using ferrite as catalyst under microwave irradiationrevealed many advantages such as high degradation ratio, rapid degradation, low cost,no secondary pollution, and so on, which showed a good and extensive applicationforegrounds.