Preparation And Adsorption Properties Of Ethyl Carbamate Magnetic Molecularly Imprinted Polymers

Ethyl carbamate（EC）is a toxic by-product inevitably produced during the fermentation,production and storage of many foods.In the 1940s,animal studies revealed its potential carcinogenicity,and EC was officially classified as a Group 2B carcinogen by the International Agency for Research on Cancer（IARC）in 1974 and further upgraded to a Group 2A carcinogen in 2007.The isolation and removal of EC are difficult due to its low content in food and the complexity of the matrix.Molecularly imprinted polymers（MIPs）prepared by molecular imprinting technique（MIT）have been used for the enrichment and removal of target compounds due to their better adsorption properties and specific recognition,and are an ideal method for the separation and removal of trace EC from fermented foods.In this study,two magnetically responsive molecularly imprinted polymers of urethane were prepared by surface molecular imprinting technique.The main research details are as follows:（1）The EC molecular imprinting system was simulated using the computational chemistry software Gaussian 09,and the density flooding theory（DFT）method was used to simulate the imprinting system with EC as the template molecule at the B3LYP/6-31+G（d,p）calculation basis.Among them,methacrylic acid（MAA）was selected as the best functional monomer by calculating the binding energy（ΔE）of the template molecule-monomer complex;the reactive sites were predicted based on the electrostatic potential energy（MEP）and NBO charge transfer,and the best blotting ratio of 1:4 was determined.The implicit solvent model calculates that toluene has a lower solvation energy and is more suitable as a porogenic agent.The simulation can reduce the experimental workload,increase the probability of success and reduce the experimental cost（2）Fe₃O₄nanoparticles with superparamagnetic properties were prepared by the co-precipitation method,and Fe₃O4@SiO₂ was modified by the modified St?ber method with silylation on its surface,and then functionalized Fe₃O₄cores were produced by grafting vinyl onto Fe₃O₄@SiO₂surface using a silane coupling agent.In combination with the surface molecular imprinting technique,ethylene glycol dimethacrylate（EGDMA）was used as the crosslinker and azodiisobutyronitrile（AIBN）as the initiator to prepare the urethane magnetic molecular imprinted polymers（EC-MMIPs）using the imprinting conditions obtained from simulations.A variety of material characterization methods were employed to characterize the polymers,and subsequent experiments to investigate their adsorption properties were conducted.The results revealed that EC-MMIPs possess excellent thermal stability,magnetic responsiveness,adsorption capacity（18.53μg/mg）and reusability.（3）Preparation of multi-walled carbon nanotubes with magnetic properties by co-precipitation method and used as magnetic carriers to prepare urethane magnetic carbon nanotube molecularly imprinted polymers（MMCNT@MMIPs）.The structure,morphology,crystalline shape,magnetic properties,and thermal stability of the polymers were analyzed using Fourier transform infrared spectroscopy（FT-IR）,swept surface electron microscopy（SEM）,X-ray diffraction（XRD）,sample vibrational magnetometer（VSM）,and thermogravimetric analysis（TGA）.In addition,the results of a series of adsorption experiments showed that MMCNT@MMIPs had good adsorption capacity and high imprinting factor,with an effective adsorption rate of 89.8%even after several cycles.