| Industrialization has brought convenience to people’s lives,but at the same time it has also brought serious damage and impact to the natural environment.One of the most important environmental problems caused by industrialization is water pollution.In order to solve the problem of water pollution,general methods for treating pollutants in water include photocatalytic oxidation,adsorption and separation of pollutants,and bioremediation of the environment.From the perspective of resource conservation and environmental improvement,as a green and safe water treatment method.Nano-zinc ferrite is a new type of semiconductor.It has certain photocatalytic performance under visible light,but its shortcomings are also obvious.It has a high photogenerated electron-hole recombination rate.In practical applications,it needs to be improved by means Photocatalytic performance.In order to improve its photocatalytic performance,this thesis focuses on nano-zinc ferrite,doped with nickel ions and zinc sulfide,and prepares photocatalysts Zn1-xNixFe2O4 and ZnS-ZnFe2O4 with different ions or substances through different preparation methods.Using rhodamine B(RhB)and methylene blue(MB)as simulated wastewater,the effects of the initial concentration of simulated wastewater,initial pH,reaction time,catalyst dosage and reaction temperature on the degradation of simulated dye wastewater were investigated.The photocatalytic reaction has the following conclusions:1.The ZnFe2O4 photocatalyst was prepared by the co-precipitation method and the sol-gel method.XRD,SEM,FT-IR characterization showed that the ZnFe2O4 photocatalyst was prepared with very high purity,with few impurity peaks and high purity.In the photocatalysis test of the degradation treatment of RhB simulated wastewater,under the irradiation of a high-pressure mercury lamp 250 W,50 mg ZFO-6(sol-gel method,annealing temperature 800℃)was used as the photocatalyst,and 100 mL 20 mg·L-1 The RhB solution is simulated wastewater,the initial pH is 6.0,and the photocatalytic reaction at 25℃ for 180 min,the degradation rate of RhB can reach 86.52%.and the degradation kinetics reaction is in line with the quasi-first-order reaction kinetics process,and the photocatalyst cycle times are tested In the 6-cycle test,the degradation rate of RhB is still maintained at about 80%,and the quality loss rate after recycling is 5%2.Zn1-xNixFe2O4(x=0,0.2,0.4,0.6,0.8,1)nanoparticles were prepared by solution combustion method.The photocatalytic test of MB solution obtained the optimal x value of 0.4.The samples were characterized by XRD and FT-IR spectra to confirm the presence of synthetic samples.Using 0.030 g Zn0.6Ni0.4Fe2O4 photocatalyst,at 25℃,0.03 g catalyst photocatalyzed 100 mL of 10 mg·L-1 MB solution for 120 min,and the MB degradation rate could reach 91.71%.Under the optimized degradation conditions,the photocatalytic degradation reaction of MB satisfies the quasi-first order reaction model.3.ZnS,ZnFe2O4,ZnS-ZnFe2O4 photocatalysts were prepared by hydrothermal method,and characterized by XRD and SEM.Then use the zinc ferrite source prepared in Chapter 1 to compound the two catalysts ZnS-ZnFe2O4-G and ZnS-ZnFe2O4-R.In the experiment,the photocatalytic effect of different catalysts on MB solution was tested.It is found that the composite photocatalyst has better performance than the single photocatalyst.Among the composite photocatalysts,the zinc ferrite prepared by the sol-gel method at 800℃ has the best performance.Using MB as the simulated dye of dye wastewater,react for 120 min under a 250 W high pressure mercury lamp,pH value 6.0,treatment temperature 25℃,and ZnS-ZnFe2O4-G catalyst dosage of 12 mg3 treat 100 mL of 10 mg·L-1 MB solution,the degradation rate can reach 94.25%.The photocatalytic reaction of MB conforms to the quasi-first-order kinetic equation,and the possible photocatalytic mechanism is proposed. |
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