Preparation Of Modified ZnO/ZrO₂ Catalyst And Its Photocatalystic Degradation Of Dye Wastewater

Dye wastewater in the water environment hazards in the larger,difficult to handle.Photocatalytic oxidation is widely used for the treatment of refractory wastewater because of its high efficiency,cleanliness,energy saving and no secondary pollution.Therefore,it is necessary to study new and efficient semiconductor photocatalysts.ZnO is a very small number of semiconductors that can achieve quantum size effects.The Sm-ZnO/ZrO₂ photocatalyst with high photocatalytic activity,stable and high efficiency was prepared by the addition of rare earth metal ion doping on the basis of the combination of Zr O 2 and ZnO with wide band gap and stable performance.Typical pollutants,focusing on the impact of various factors on its photocatalytic activity,optimize the degradation process parameters,and initially explore the reaction mechanism.The details are as follows:A series of ZnO,ZnO₂ and ZnO/ZrO₂ composite photocatalysts were prepared by hydrothermal method.By characterization and photocatalytic activity ev aluation,it was proved that the composite catalyst was composed of six square ZnO and tetragonal phase ZnO₂.The composite of ZnO₂ changed the morphology of ZnO and promoted the growth and crystallization of ZnO,the surface area increased,the light absorption capacity was enhanced,and the separation rate of light carrier was high.The photocatalytic activity of ZnO/ZrO₂ composite photocatalyst is the highest,with zinc acetate as zinc source,Zn/Zr molar ratio of 1:1 and hydrothermal temperature of 160 degrees centigrade,which is 14.0% higher than ZnO and 78.8% higher than that of ZnO₂.The optimum conditions for the preparation of ZnO/ZrO₂ composite catalysts were studied.The results showed that the addition of rare earth metal samarium doped with 0.5%,the hydrothermal temperature was 160 °C and the hydrothermal time was 12 h,the Sm-ZnO/ZrO₂ composite catalyst has the highest photocatalytic activity,which is 24.0% higher than that of ZnO/ZrO₂ composite catalyst.Sm doping can increase the specific surface of the ZnO/ZrO₂ catalyst and enhance the optical absorption capacity of the UV light region.In the Sm-ZnO/ZrO₂ catalyst,part of Zr4+ was converted to Zr3+,the lattice O2-decreased,the oxygen vacancy increased,the active site increased,and the isolation rate of photo generated carriers increased.The Sm-ZnO/ZrO₂ catalyst has a certain applicability for different dyes and has the best photocatalytic activity under neutral conditions.Under the conditions of different kinds of dyes,p H and initial concentration of reactant,the reaction of photocatalytic degradation of rhodamine B by Sm-ZnO/ZrO₂ conforms to the first order kinetic model.After repeated use of 5 cycles,the Sm-ZnO/ZrO₂ catalyst still maintains high efficiency and no loss of life,and has good stability.In the photocatalytic degradation of rhodamine B reaction,the activity sequence of the active species is h+> ·O2->·OH;In the reaction of photocatalytic degradation of methylene blue,the activity sequence of the active species is a lso h+> ·O2->·OH;In the reaction of photocatalytic degradation of methyl orange,the activity sequence of active species is ·O₂^->h⁺>·OH.