Synthesis And Adsorption Application Of Hydrogel Crosslinked By Ionic Liquids

Water pollution seriously threatens the human environment and health,hydrogel is widely used in water treatment due to its low cost,designable structure,and environmental protection.In this paper,two ionic liquids are designed and used as cross-linking agents to synthesize hydrogels,and the influence of ionic liquid cross-linking hydrogels on swelling rate and other factors as well as the adsorption mechanism of hydrogels on heavy metal ions and dyes in water are studied.The research content Explained as follows:（1）Two kinds of polymerizable ionic liquids[Vim]Br₂,[DMAEMA]MA were synthesized from 1-vinylimidazole（Vim）,1,2-dibromoethane,dimethylaminoethyl methacrylate（DMAEMA）and maleic acid（MA）by quaternization and acid-base neutralization,respectively.The yields were 89%and 92%,respectively.The structure of ionic liquid was determined by ¹H NMR and IR.（2）PAM/PAA/[Vim]Br₂ hydrogel was prepared by using[Vim]Br₂ as an ionic crosslinking agent and acrylamide（AM）and acrylic acid（AA）as mono system.Scanning electron microscopy shows that the prepared hydrogel has a clear layered structure and large pores.By the optimization of hydrogel synthesis conditions,it is found that when the amount of ionic liquid was 0.8%of monomer mass,the maximum swelling rate can reach 33769%,It is found that the removal efficiency of four heavy metal ions by hydrogels is over 90%.The adsorption behavior of Ni²⁺,Cu²⁺,Zn²⁺and Cr³⁺in water by hydrogels was discussed.It was found that PAM/PAA/[Vim]Br₂ hydrogels had better removal efficiency at low and high concentrations compared with N,N-methylene bis acrylamide（MBA）crosslinking agents.Further studies showed that the adsorption of hydrogels in different concentration ranges had different adsorption mechanisms,at low concentration,the adsorption of heavy metal ions by hydrogels accords with multilayer physical adsorption,at high concentrations,the adsorption of heavy metal ions by hydrogels accords with monolayer chemisorption.（3）PAA/PAM/[DMAEMA]MA hydrogels were synthesized by adding different amounts of[DMAEMA]MA as crosslinking agents.IR analysis confirmed that the hydrogel was successfully prepared.SEM analysis showed that the prepared hydrogel channels were uniform and dense.The preparation process of hydrogels was optimized by response surface methodology.The swelling rate of hydrogels could reach 59900%.The adsorption experiments showed that the adsorption capacity of the four kinds of dye molecules was very high by hydrogel,and the adsorption isotherms and other related calculations showed that the hydrogel had different adsorption mechanism for different structure of dye molecules.