Study On Photocatalytic Removal Of Bromate By Eu Doped TiO₂

Photocatalytic technology has received extensive attention as an efficient and safe environment-friendly environmental purification technology.However,single titanium dioxide(TiO2)photocatalyst has a certain degree of recombination rate due to its wide band gap and high photogenerated charge.It restricts its application in actual production.The rare earth element has incomplete 4f orbital and empty 5d orbital,which is easy to produce multi-electron configuration,can effectively inhibit the recombination of photogenerated electron holes,or change the band structure of TiO2,resulting in the change of photocatalytic activity of TiO2.In order to improve the catalytic activity of TiO2 photocatalytic removal of bromate in water.Titanium dioxide was doped by rare earth metal to expand its photoresponse range and improve its solar light utilization rate,which provides a theoretical guidance for photocatalytic removal of bromate in this paper.The hydrazine-modified titanium dioxide was prepared by one-step hydrothermal method,and the photocatalytic activity of bromate in water was studied as a catalyst.The activity of Eu-TiO2 photocatalytic removal of BrO3-under UV light was investigated.It was found that the doping of rare earth metal Eu can significantly improve the photocatalytic activity of bromate compared with the photocatalytic removal of bromate by TiO2 alone(29.8%removal rate).Under the action of ultraviolet light(10W,26μW/cm2,wavelength 254nm),the initial concentration of bromate is 100μg/L,Under the condition of water temperature is 22±2℃,the dosage is 0.05g/L 1%Eu-TiO2 photocatalyst and pH=5.7±0.2,the removal rate of bromate can reach 95%at 30 min.The effect of Eu doped,catalyst dosage,pH,initial concentration of bromate and different coexisting anions of Eu-TiO2 on the activity of Eu-TiO2 photocatalytic removal of BrO3-in Eu-TiO2 material was studied.The removal activity of the TiO2 photocatalyst is first increased and then decreased,and the optimum loading is 1%.The lower the pH,the higher the catalytic activity of the catalyst.The removal rate of 82.1%at pH=3.1 and also contradicts the experimental results in the fourth chapter,The main reason is that pH has a strong influence on the static charge on the surface of the TiO2 photocatalyst.The dosage of the catalyst increases,the reaction rate increases,and the removal rate increases first and then decreases.The presence of anions inhibited the removal of BrO3-by Eu-TiO2 to a certain extent.After reaching a certain concentration,the inhibitory effect was weakened.At the same time,the prepared Eu-TiO2 materials were characterized by X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),fluorescence spectroscopy(PL),X-ray diffraction(XRD),and the results were combined.The mechanism of photocatalytic removal of bromate was discussed.The photocatalytic removal of the bromate by the Eu-TiO2 material is carried out by reduction to reduce the bromate to bromide.The doping of Eu in the doped Eu-TiO2 material of Eu element strengthens the {101} crystal plane while suppressing the recombination of electron-hole pairs.The band gap of the catalyst is narrowed from 2.92 to 2.71 eV,to some extent.The photoresponse range of the catalyst is broadened,thereby significantly increasing the catalytic activity.Eu-TiO2 material performs well in the test of repeatability and stability of the bromate removal,indicating that Eu-TiO2 is a promising photocatalyst.