Preparation And Characteristics Of The Deltamethrin Molecularly Imprinted Polymers

As novel materials,molecularly imprinted polymers(MIPs)have high affinity and selectivity for template.MIPs with easy operation,stable quality and low cost have been widely used in chromatographic separation,solid phase extraction,sensor,drug delivery and enzyme mimetic catalysis.In this paper,deltamethrin(DM)molecularly imprinted polymers were prepared by precipitation polymerization and two-step seed swelling polymerization,and its adsorption performance were studied,the main achievements are as follows:(1)Deltamethrin as template molecule,acrylic acid(AA),acrylamide(AM)and methacrylic acid(MAA)as functional monomer,The molecular imprinting pre-assembled system was studied by computer simulation techniques and UV spectrum analysis.Results show that in the acetonitrile solvent,interaction pecking order for deltamethrin and functional monomer as follow:AM>AA>MAA,when the ratio was 1:4 between DM and AM,imprinted efficiency was the best,and the binding constant K was 6.614×10~5.On this basis,MIPs were prepared by precipitation polymerization,and its synthetic formula was optimized through orthogonal experiment.The results indicated that deltamethrin 1mmol,acrylamide 4 mmol,acetonitrile 40 mL,ethylene dimethacrylate 20 mmol,azodiisobutyronitrile 4 mmol,the MIPs had bigger saturated adsorption capacity of 66.48mg/g.The synthesized polymers showed porous structures with specific surface area of90.78m~2/g and average pore size of 15.83 nm.(2)The static adsorption isotherm experiment and model fitting were used to estimate the adsorption properties of deltamethrin MIPs which prepared by precipitation polymerization.The equilibrium data correlated well with a Freundlich isotherm followed by a Halsey isotherm model which indicated heterogeneity of the adsorbent surface and multilayer selective adsorption of deltamethrin onto MIPs.The pseudo-second order kinetic models could well reflect the adsorption process.The synthesized polymers were evaluated as solid-phase extraction(SPE)sorbents for isolation and preconcentration of deltamethrin and its analogues cypermethrin,lambda-cyhalothrin and bifenthrin.The recoveries of deltamethrin from different tea liquor samples were in the range of 88.73%to116.15%.The MIPs exhibited higher affinity for deltamethrin over competitive compounds and the corresponding separation factor?were more than 1.(3)The single factor test was used to research the preparation factors by two-step seed swelling polymerization.The well synthetic conditions were:seeds 2 g,deltamethrin 1mmol,Acrylamide 6 mmol,chloroform as solvent.The synthesized polymers had bigger saturated adsorption capacity of 75.72 mg/g,the imprinted factor was 7.225.The results showed that the MIPs had pore structure and its specific surface area was 90.78m~2/g,average pore size was 9.142 nm with good heat stability.The adsorption equilibrium time was 0.333 h.The adsorption isotherms were fitted with Freundlich isotherm and Halsey isotherm,the adsorption of DM on MIPs was a favorable adsorption process.The adsorption capacity reduced with the increase of the solution temperature.The result of the selective adsorption experiment showed that the MIPs had high affinity and excellent recognition selectivity for the template molecule DM.The enrichment condition of molecularly imprinted solid-phase extraction were optimized,when activation of the solvent is water and elution solvent is methanol,the average recoveries of deltamethrin from different tea liquor samples were all excess 80%.The average absorptivity of polyphenol in different tea liquor samples were in the range of 11.28%to 32.14%.