Synthesis Of Salt-tolerant Hydrogel And Its Application In Water Treatment

Hydrogels are soft elastic materials that swell without dissolving in water,in which the liquid is fixed in a unique three-dimensional crosslinked network.Hydrogels have excellent permeability,adsorption,stimulus response,biocompatibility,and ionic conductivity.They have made great progress in the fields of industry,agriculture,biomedicine,and intelligent new materials.They have been synthesized in recent decades.One of the hot topics in materials research.In order to better use hydrogels in the above fields,the problem that hydrogels have poor mechanical properties under salt media conditions has not been well solved,and the adsorption properties of hydrogels will decrease with the increase of salt concentration.In order to overcome the adverse effects of salt on the mechanical properties of hydrogels,a simple method was designed to prepare a strong hydrogel P(AAm-co-HFBMA)hydrogel with salt enhancement effect.Swelling properties and dye adsorption tests under different concentrations of salt were carried out.The main contents are as follows:1.Copolymerization of acrylamide(AAm)monomer and hexafluorobutyl methacrylate(HFBMA)monomer in a DMF / water mixed solvent,combined with solvent replacement method to prepare hexafluorobutyl methacrylate-acrylamide hydrogel [P(AAm-co-HFBMA)Hydrogel].The results show that for the gel samples with AAm: HFBMA = 75:25 mol / mol,when the salt concentration increases from 0 mol / L to 2 mol / L,the tensile strength increases from 2.34 MPa to 3.50 MPa.2.In this study,the salt enhancement mechanism of gel was systematically studied by DSC,fluorescence and scanning electron microscopy.The results showed that after the immersion of P(AAm-co-HFBMA)gel into the salt solution,the hydrogel network gradually subsided with the penetration of small molecule salt.Therefore,due to the collapse of the network and the hydrophobic interaction between the CF groups,the hydrophobic CF units hanging on the network are easier to aggregate and form dynamic crosslinking points.These dynamic physical crosslinks can provide more effective energy dissipation mechanism for the gel,and endow the hydrogels with excellent salt enhancement properties.P(AAm-co-TFPMA)prepared by AAm and TFPMA was tested by DSC,which further proved the salt strengthening effect of fluorine-containing monomers.3.Comparison of swelling performance and dye adsorption at different salt concentrations,P(AAm-co-HFBMA)hydrogel the swelling performance of the gum is very stable under different salt concentrations.The results of malachite green adsorption experiments under different salt concentrations show that salt promotes the hydrogel adsorption effect,and the adsorption capacity increases from 11.63 mg/g(0 mol/L)to 24.64 mg/g(2mol/L).In order to increase the adsorption capacity,the P(AAm-co-AAc-co-HFBMA)hydrogel was prepared by adding AAc monomer in a small proportion.Adsorption in deionized water increased to 32.69 mg/g,and 20.78 mg/g in 2 mol/L salt,it still retains high adsorption capacity.