甲基对硫磷分子印迹聚合物制备中溶剂和功能单体的影响

Influence of Solvents and Functional Monomers on Preparation of Methyl Parathion Molecularly Imprinted Polymers

为了有效的分离富集水样中的有机磷农药,以甲基对硫磷为模板、二甲基丙烯酸乙二酯为交联剂,采用传统方法制备了甲基对硫磷分子印迹聚合物(MIPs)。考察了三种溶剂和三种功能单体及其用量对MIPs吸附性能的影响。结果表明,以氯仿为溶剂制得的MIP特异性最强,溶剂用量对MIPs比表面积和溶胀比的影响显著。氯仿用量为35mL时MIP性能最理想;1H-NMR研究显示,4-乙烯基吡啶(4VP)与模板分子通过π-π堆积作用形成稳定的复合物,按4VP与模板分子摩尔比4:1制得的MIP特异性和亲和性较理想。测定了该MIP的吸附等温线,利用Langmuir等温式分析结果,得出其饱和吸附量为625.5μmol?g?1,明显高于非印迹聚合物的饱和吸附量285.7μmol?g?1。利用该MIP对模拟海水样品进行研究,结果显示,MIP对不同有机磷农药的吸附能力表现出一定的差异。通过进一步优化,提高MIPs的选择性,该材料有望用于水样中甲基对硫磷的分离富集和分析。

In order to separate and concentrate the organophosphorus pesticides in water efficiently, the molecularly imprinted polymers （MIPs） were synthesized by bulk polymerization with methyl parathion as template molecule and ethylene glycol dimethacrylate as crosslinking agent. A number of experiments were conducted to investigate the factors, such as the species and amount of the used solvent and functional monomer, which are likely to be the important factors affecting the recognition properties of MIPs. It was found that both the specific area and swelling ratio of the MIPs prepared vary significantly as the used solvent volume changes, and the MIP prepared with chloroform as the solvent exhibits high selectivity for methyl parathion. The ^1H-NMR spectra show that the functional monomer 4-vinylpyridine （4VP） forms stable complex with template molecules via n-n accumulation effect; and the experimental results indicate that the 4VP is more efficient to be used as the functional monomer than other two tested monomers, methacrylic acid （MAA） and acrylamide （MA）, especially when the used molar ratio of 4VP to template is 4：1. Moreover, the adsorption isotherm of the MIP prepared with 4VP： template=4：1 was studied, and the Langmuir isotherm analysis shows that the maximum adsorption capacity of this MIP is 625.5μmol·g^-1, which is much higher than that of the nonimprinted polymer （NIP） （285.7μmol·g^-1）. The above prepared MIP was also used to extract different kinds of organophosphorus pesticides in seawater sample, and it exhibits different afffmities toward different pesticides with various molecular structures. It seems that, after improving and enhancing the selectivity of the prepared MIP, it is hopeful to be used to separate and concentrate specially the methyl parathion in water.