硅胶表面分子印迹聚合物对DEHP的选择性吸附

Selective adsorption of DEHP by molecularly imprinted polymer on surface of silica gel

采用硅烷偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)对硅胶进行改性,并以改性硅胶为载体、邻苯二甲酸二(2-乙基)己酯(DEHP)为模板分子、甲基丙烯酸(MAA)为功能单体,采用表面接枝聚合法合成DEHP-硅胶表面分子印迹聚合物,考察了物料比、反应温度、反应时间对聚合物性能的影响,确定了最佳制备条件。采用傅里叶变换红外光谱、扫描电镜对印迹聚合物进行表征,并对其吸附性能进行了研究。结果表明,最佳制备条件为:模板分子、功能单体、交联剂的摩尔比为1∶4∶12、反应温度60℃、反应时间24 h。红外光谱显示印迹聚合物成功接枝到硅胶表面,扫描电镜分析表明,印迹聚合物表面粗糙,出现了对模板分子DEHP产生选择性识别的孔穴。与DBP、DEP、DMP和DNOP相比,印迹聚合物对DEHP的吸附具有高选择性,吸附DEHP的最适pH为7,吸附平衡时间100 min。吸附等温线可用Langmuir和Freundlich模型描述,饱和吸附量为7.262 mg·g^(-1)。吸附速率可用准二级吸附动力学模型描述。

Molecularly imprinted polymers were prepared using a surface imprinted technique on silica gel modified by γ-methylacryloyloxypropyltrimethoxy silane（ KH-570）,DEHP as the template molecule,and methacrylic acid as a functional monomer. The effects of the material ratio,reaction temperature,and time on the properties of the polymers were investigated and the optimal preparation conditions were determined. The printed polymers were characterized by Fourier transform infrared（ FT-IR） analysis and scanning electron microscopy,and their DEHP adsorption properties were studied. The results indicated the following optimal preparation conditions：a 1 ∶ 4 ∶ 12 mole ratio of DEHP： MAA： EDGMA,a reaction temperature of 65 ℃,and 24 h of reaction time. The FT-IR spectra showed that the printed polymers were grafted onto the surface of the modified silica gel. The SEM images implied that the printed polymer was rough and porous,resulting in specific recognition for DEHP; they exhibited higher adsorption selectivity for DEHP than that of its structural analogues. The adsorption capacity was optimized at pH 7 with an adsorption equilibrium time of 100 min. The isothermal adsorption process was well described by Langmuir and Freundlich models,a saturated adsorption capacity of 7. 262 mg ·g-1,and a pseudosecond-order kinetic model of adsorption kinetics.