Crown Ether Functionalized Porous Polymers For Selective Adsorption Of Lithium(?) And Their Adsorption Behaviors And Mechanisms

Lithium(Li)is an important metal,it is widely used in lithium battery,ceramics,glass fabrication,metallurgy,ceramics and other fields.Salt-lake brine is an important source of lithium supply.However,the components of salt-lake brine are complex,and the interfering ions lead to difficulties for lithium extraction.Therefore,the selective extraction of lithium from salt-lake brine is of great importance.There are many methods to extract lithium from salt-lake,among which adsorption shows distinct advantages.However,the existing Li~+adsorbent suffered from poor stability,slow kinetics performance and limited selectivity.Crown ethers with a 12-to 14-membered ring possess strong binding affinity toward Li~+.PolyHIPEs prepared by HIPEs template are ideal substrate for adsorbent.The preparation and surface modification of PolyHIPEs are simple.Therefore,functional porous polymer constructed by crown ethers and the surface modification of PolyHIPEs can overcome the drawbacks of existing Li~+adsorbents.In this thesis,three kinds of crown ether functionalized porous polymer were prepared by combining CEs and the surface modification of PolyHIPEs.The mechanism and behavior of Li~+adsorption by these adsorbents were investigated.The details are listed as follows:(1)Preparation of 2-methylol-12-crown-4 ether immobilized PolyHIPEs and the study of behavior and mechanism of selective adsorption for lithium(I)First,stable HIPEs template was prepared by adding glycidyl methacrylate monomer in the oil phase and using Hypermer2296 as emulsifier.Subsequently,a porous polymer with abundant epoxy groups on its surface was obtained by thermal initiated polymerization.Then,the porous polymer adsorbent was modified with CEs by the reaction of 2M12C4 with epoxy group.The structure,morphology and chemical composition of PGMA-CE were studied by combining various characterization methods.The results showed that PGMA-CE has interconnected porous structure,and2M12C4 is bonded on its surface by chemical bond.The selective adsorption of Li~+by PGMA-CE was studied by static adsorption experiments.The results reveal that PGMA-CE has excellent performance for Li~+adsorption.PGMA-CE possessed a maximum equilibrium adsorption capacity of 3.15 mg/g for Li~+,and the adsorption equilibrium was reached within 3.0 h.PGMA-CE overcomes the poor stability and slow kinetic performance of traditional Li~+adsorbents.(2)Surface initiated polymerization of crown ethers for the preparation of functional polymer and the study of behavior and mechanism of selective adsorption for lithium(I)First,a stable HIPEs template was prepared by adding 4-VBC to external phase and using Hypermer2296 as emulsifier.Subsequently,a porous polymer with chloromethyl groups on its surface was obtained by thermal initiated polymerization.The initiation site was modified on the surface of the porous polymer by the reaction of sodium thiosulfate and chloromethyl groups.Then,grafting of CEs chains on the surface of porous polymer was accomplished by the polymerization of 2AM12C4 under UV radiation,and PVBC-g-PCE with high density of CEs groups was prepared.The structure,morphology and chemical composition of PVBC-g-PCE were studied by combining various characterization methods.The selective adsorption performance of PVBC-g-PCE for Li~+was studied by static adsorption experiments.Due to the presence of high-density crown ether groups,PVBC-g-PCE exhibited fast kinetics,high adsorption capacity and excellent selectivity.PVBC-g-PCE has overcome the drawbacks of low density and deep embedding of active site in existing organic/composite Li~+adsorbent.(3)Preparation of Crown ethers functionalized polymer via SI-ATRP and post-modification and the study of behavior and mechanism of selective adsorption for lithium(I)First,PolyHIPEs with abundant benzyl chloride groups on its surface was prepared by the addition of 4-VBC in HIPEs template,and SI-ATRP polymerization of GMA on the surface of the porous polymer was initiated to graft polymer brush.The grafted polymer brush contains abundant epoxy groups.Then,PVBC-g-PGMA-CE with high density of crown ether groups on its surface was prepared by modification of 2AB12C4on grafted polymer brush.The morphology,structure,chemical composition and content of PVBC-g-PGMA-CE were studied by combining various characterization methods.The results showed that high density of 2AB12C4 was modified by SI-ATRP and chemical post-modification.The selective adsorption of Li~+by PVBC-g-PGMA-CE was studied by static adsorption experiments.The results show that PVBC-g-PGMA-CE possess fast adsorption kinetics,high adsorption capacity and excellent selectivity.PVBC-g-PGMA-CE solves the current hindrance of low density and deep embedding of active site in existing Li~+adsorbents,what's more,it provides a strategy with strong controllability,wide applicability and simple operation for the construction of highly efficient Li~+adsorbent.