Regulation Crystal Facet Defects Of Zr-MOFs And The Research On Heavy Metal Ions Removal

With the rapid development of modern industry,it is unavoidable to be polluted by thousands of poisonous and harmful substances produced in various ways,and the whole ecosystem is destroyed by the circulation of water.Heavy metal arsenic(As)and antimony(Sb)are especially harmful to environment and human health.Therefore,it is very important to explore effective methods to remove heavy metals without secondary pollution for wastewater treatment.In order to achieve this goal,this subject uses functional group modification,calcining and rare earth doping to regulate the crystal surface of Zr-MOFs.The adsorption properties of arsenic As(Ⅲ),As(Ⅴ)and antimony ions Sb(Ⅲ),Sb(Ⅴ)are studied around the dominant adsorbent crystals.The main contents are as follows:(1)Prepared ZrO(OH)2,UiO-66,UiO-66-NH2 and UiO-66-SH then calcined at900℃ and induced the change of crystalline state of Zirconium oxide as adsorbents for explore the enhance of adsorption in aqueous solution on Arsenic ions.The crystal modifications of Zirconium oxide exists in Monoclinic which were calcined at 900 ℃.Through modification method decorated the Metal-organic frameworks(MOFs)material and after calcination were changed the specific surface area and partical size of Zirconium oxide.Take advantage of the exposed defect {111}crystal to improve performance of the adsorption capacity of arsenic in water.The isothermal adsorption experiment show that the best adsorption properties of Zr-MOF(UiO-66)is theUiO-66-SH after calcined at 900 ℃ on As(Ⅲ)and As(Ⅴ)were 81.77 mg/g and 85.90 mg/g respectively.The adsorption kinetics fitted the pseudo-second-order rate equations.The Dubinin-Radushkevich(D-R)isothermal adsorption model fitting showed that the adsorption process was chemisorption.After calcination,the specific surface area and pore size of ZrO2 material are greatly reduced.Through the analysis of the correlation coefficient,the adsorption properties changed large on Arsenic can be attributed to the exposed the advantages of adsorption crystal on defect {111}.So the effect of physical adsorption was further excluded.BET specific surface area,scanning electron microscope(SEM),X-ray diffraction(XRD)and Fourier Transform Infrared Spectrometer(FT-IR)were used as characterization.(2)Rare earth doped UiO-66@Sm,UiO-66@Eu,UiO-66@Er and UiO-66@Tm were prepared by hydrothermal method.The maximum adsorption capacity of these materials for heavy metals Sb(Ⅲ)were 165.8 mg/g,162.2 mg/g,92.2 mg/g and 94.8 mg/g respectively.While for Sb(Ⅴ)were 254.3mg/g,241.6mg/g,84.8mg/g,and 86.2mg/g respectively.The adsorption kinetics fitted the pseudo-second-order rate equations showed that the adsorption process was chemisorption.The crystal form of XRD is consistent with the standard UiO-66.The specific surface area of BET confirms that the specific surface area of UiO-66@Sm and UiO-66@Eu is also close to the specific surface area of UiO-66 in literature,which is 424.30 m2/g and 410.98m2/g respectively.Compared with the UiO-66 reported in other literature,the adsorption effect is better under similar specific surface area and similar crystalline SM doped UiO-66@Sm and europium doped UiO-66@Eu.The above rare earth doped UiO-66 was also treated by calcining at900 ℃.However,the adsorption effect of ZrO2 rare earth doped materials on As(Ⅴ)after calcining at 900 ℃ was greatly reduced,and the reason for it was to be further explored.Both ZrO2 and rare earth doped materials synthesized by Zr-MOFs have good acid-base stability and thermal stability to effectively remove arsenic and antimony.