Synthesis of a novel 1-ethyl-3-methylimidazolium chloride ionic liquid molecularly imprinted polymer and its properties of specific adsorption and solid phase extraction

Abstract

1-ethyl-3-methylimidazolium chloride (C2mimCl) ionic liquid molecularly imprinted polymer (C2mimClMIP/PS-DVB) was prepared on the surface of poly (styrene-divinylbenzene)(PS-DVB) by using C2mimCl as the template molecule, methacrylic acid (MAA) and ethyleneglycol dimethacrylate (EGDMA) as the bifunctional monomer. The preparation conditions were optimized and the molar ratio of 1:4:14 for C2mimCl: MAA: EGDMA was selected as the optimal polymerization molar ratio. Then infrared spectra (IR) spectrophotometer, scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area and pore size analyzer were used to characterize the molecularly imprinted polymer, it was shown that C2mimClMIP/PS-DVB was successfully prepared on the surface of PS-DVB. The static adsorption experiments were performed in acetonitrile to investigate the adsorption properties and selective recognition characteristics of the polymer for C2mimCl and its structural analogues. Selective adsorption experiments showed that C2mimClMIP/PS-DVB has high selectivity for C2mimCl and C4mimCl; Adsorption isotherm experiments suggested that the maximum adsorption capacity of C2mimClMIP/PS-DVB and C2mimClNIP/PS-DVB for C2mimCl was 144.71 μmol/g and 22.56 μmol/g, respectively, and for C4mimCl was 124.53 μmol/g and 21.42 μmol/g. While the total number of binding sites Nt, mean association constant K0 and the heterogeneity index m of C2mimClMIP/PS-DVB were 130.9 μmol/g, 0.37 L/mmol and 0.8, respectively. C2mimClMIP/PS-DVB solid phase extraction column was prepared to invest the solid phase extraction properties of C2mimClMIP/PS-DVB. Various parameters, such as the loading volume, flow rate and eluent solvent, were optimized for the C2mimClMIP/PS-DVB solid phase extraction column experiments. Then the dynamic adsorption experiments were carried out by coupling C2mimClMIP/PS-DVB solid phase extraction column with high performance liquid chromatography (HPLC), it was shown that C2mimClMIP/PS-DVB solid phase extraction column could separate and enrich C2mimCl and C4mimCl selectively in the presence of their structural analogues, which also exhibited inherent stability and good reusability. The C2mimClMIP/PS-DVB solid phase extraction column was finally applied to separate and enrich C2mimCl in the ground water samples and exhibited good practicability. © 2012 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.