The Preparation Of Magnetic Ion-imprinted Polymers And Their Applications In Salt Lake Brine

The Qinghai Province has unique salt lake resources whichis rich in cesium and other rare elements.However,the concentration of cesium in brine is very low,although salt lake has substantial cesium resources.Furthermore,the component of salt lake brine is complex,and the physical and chemical properties of symbiotic elements are very similar.So it is very difficult to separate cesium from salt lake brine.Metal ion imprinting technology can achieve water-soluble metal ions imprinting and identification in the water phase.Metal ion-imprinted polymers greatly increase the adsorption selectivity of metal ions in the liquid phase.In this work,the preparation method of surface magnetic metal ion-imprinted polymer was discussed firstly by using lead ion as template.On the basis of this method,two cesium ion-imprinted polymers were prepared by using cesium ion as template,to separate the cesium ions from the complex salt lake brine system,and the adsorption properties of these imprinted polymers were carried out.The concrete research contents are as follows:?1?A magnetic Pb?II?ion-imprinted polymer was prepared by surface imprinted sol-gel method,using magnetic Fe₃O₄@SiO₂ microspheres as supporter and Pb?II?as template.And the structure and properties of the polymer were characterized.The equilibrium adsorption capacity of Pb?II?-IIP to Pb?II?in solution is 158.56 mg/g.The limit of detection?LOD,3Sb/m?for lead ion was 3.18 ng/L,and the recoveries of Pb?II?in industrial wastewater were between 94% and 106.1%,indicating that Pb?II?-IIP is a suitable magnetic solid phase extraction agent for Pb?II?.?2?A Cs?I?magnetic ion-imprinted polymer?Cs?I?-MIIP?was prepared by surface imprinting technique,using Fe₃O₄@Si O₂ as supporter,Cs?I?as template ion,and carboxymethyl chitosan as functional monomer.The product was characterized by FT-IR,XRD,EDS,SEM,TGA,and VSM.The equilibrium adsorption capacity was36.15 mg/g.The pseudo-first-order kinetic model and the Freundlich isotherm model were applied to predict the adsorption process of Cs?I?onto Cs?I?-MIIP.Selectivity experiments showed that the relative selectivity coefficient?k??were 24.995,1.73,1.43,4.83 and 1.63 to Cs?I?/Li?I?,Cs?I?/Na?I?,Cs?I?/K?I?,Cs?I?/Rb?I?and Cs?I?/Sr?II?binary solutions,respectively.Furthermore,Cs?I?-MIIP was applied to separateCs?I?from the salt lake brine of Qinghai,with the adsorption efficiency of 71.60% under the selected adsorption conditions.?3?To increase the adsorption capacity of imprinted polymer,the magnetic Fe₃O₄@TiO₂@SiO₂ microspheres were firstly synthesized by sol-gel method.The Cs@Fe₃O₄@TiO₂@SiO₂ was further prepared using Fe₃O₄@TiO₂@SiO₂ as supporter,carboxylated chitosan as a functional monomer and glutaraldehyde as a crosslinkingagent.The maximum adsorption capacities of Cs@Fe₃O₄@TiO₂@SiO₂ and NIP were70.88 mg/g and 40.03 mg/g,respectively.The adsorption kinetics followed the pseudo-second-order kinetic equation,and isothermal adsorption is consistent with the Freundich adsorption model.The Cs@Fe₃O₄@TiO₂@SiO₂ has a good adsorption selectivity for Cs?I?,and the relative selectivity of Cs?I?/Na?I?is as high as 156.892.Furthermore,the adsorption capacity of Cs?I?was 5.30 mg/g under the selected adsorption conditions,which adsorbed up to 74.65% of Cs?I?ions in the salt lake brine of Qinghai.