Preparation Of New Solid Phase Materials And Their Adsorption Of Scandium,Yttrium And Separation Of Zirconium And Hafnium

Rare earth elements have special electronic structure and they have excellent physical,chemical,magnetic,optical and electrical properties.They are widely used in national defense,aerospace,metallurgy,chemical,nuclear and other fields,but rare earth elements have similar properties and low storage.It is unevenly distributed and symbiotic in minerals and difficult to separate.The traditional extraction technology of scandium and yttrium and the separation process of zirconium and hafnium have serious pollution problems,so industrial applications are limited.It is urgent to develop environmentally and friendly extraction and separation technologies of scandium,yttrium,zirconium and hafnium.Solid phase extraction separation has attracted much attention due to its high efficiency,convenience and low environmental pollution.Therefore,designing and preparing solid phase extracting agent with high adsorption capacity and high selectivity has important practical significance for the extraction of scandium,yttrium and zirconium and hafnium.Metal-organic framework materials?MOFs?have higher specific surface area,adjustable pore size and post-modification control,which have attracted more and more attention in the field of metal ion separation.In addition,the dendrimer contains a large number of functional groups.The presence of molecules in the cavity makes it easy to encapsulate and adsorb metal ions,and has good chelation and molecular recognition properties for metal ions.It is considered to be a green environmentally friendly extractant.Based on this,UiO-66-NH₂MOFs and mesoporous silica loaded PAMAM dendrimers were prepared by post-modification method.The two kinds of solid phase extractants were extracted from scandium,yttrium zirconium and hafnium.The main contents include the following aspects:The UiO-66-NH₂ MOFs were synthesized by solvent thermal method.The new MOFs functionalized by salicylaldehyde?SA-UiO-66-NH₂?were prepared by post-modification control.Eu³⁺@SA-UiO-66-NH₂ was prepared by ion exchange.Uio-66-NH₂ type MOFs were characterized by FT-IR,TGA and XRD.The adsorption properties of the prepared MOFs on scandium,yttrium,zirconium and hafnium were studied.The effects of pH value,adsorption time,different temperature and initial concentration of solution on the adsorption amount were investigated.Under the optimal experimental conditions,the maximum adsorption capacities of UiO-66-NH₂ and SA-UiO-66-NH₂ for scandium were 18.54 mg/g and 8.04 mg/g,respectively.The maximum adsorption capacity yttrium was 12 mg/g and 25 mg/g.Under the optimal experimental conditions,the maximum adsorption capacity of SA-UiO-66-NH₂ for zirconium and hafnium is Q_Zr=21.61 mg/g,Q_Hf=1.44 mg/g,and the separation coefficient of zirconium and hafnium(?_Zr/Hf)was 2.2;the maximum adsorption capacity of Eu³⁺@SA-UiO-66-NH₂ for zirconium and hafnium was Q_Zr=21.61 mg/g,Q_Hf=1.38 mg/g,and?_Zr/Hf=2.3.The kinetic analysis showed that the adsorption of Sc,Y,Zr and Hf by UiO-66-NH₂,SA-UiO-66-NH₂ and Eu³⁺@SA-Uio-66-NH₂ accorded with the first-order kinetic adsorption process.3.PAMAM dendrimers were prepared by divergent synthesis and bonded to mesoporous silica.The structure of the adsorbent was modified by phenylphosphoryl dichloride?P-G1MSNs?.The structure was characterized by FT-IR,SEM and TGA.The adsorption and separation properties of P-G1-MSNs for zirconium and hafnium were studied.The effects of pH,adsorption time,adsorption temperature and initial concentration on the adsorption capacity were investigated.The results showed that under the optimal experimental conditions,the adsorption amount reached to maximum,Q_Zr=25.74mg/g and Q_Hf=5.36 mg/g,respectively.At this time,the separation coefficient is 0.56<1,and the prepared material has preferential selectivity for hafnium.The results of kinetic analysis indicated that the adsorption of Zr and Hf by P-G1-MSNs materials followed the first-order kinetic adsorption process.The adsorption behavior was in line with the Langmuir model and was a single-molecule adsorption process.The thermodynamic analysis showed that the adsorption process was a spontaneous endothermic adsorption process.