胺基化PGMA交联微球对胆红素的吸附机理

Adsorption Mechanism of Bilirubin on Aminated Crosslinking Microspheres of PGMA

通过胺基与环氧键之间的开环反应,用己二胺及多乙烯多胺等小分子胺化试剂对聚甲基丙烯酸缩水甘油酯(PGMA)交联微球进行了化学改性,制得了胺基化的PGMA交联微球,研究了该功能微球对胆红素的吸附特性,考察了胺化试剂的分子结构、介质pH值、离子强度及温度等因素对其吸附性能的影响,较深入地研究了吸附机理.实验结果表明,胺基化微球对胆红素具有强吸附作用,吸附容量可达17.80mg·g-1,等温吸附服从Freundlich方程.胺基化微球与胆红素分子之间的作用力以静电相互作用为主,同时也存在氢键作用与疏水相互作用.在pH值为6的介质中二者之间的静电作用最强,胆红素吸附容量最高.高离子强度不利于静电相互作用,盐度增大使吸附容量减小.温度升高有利于疏水相互作用而不利于氢键作用,两种作用中占优势者主导温度对吸附容量的影响.用己二胺改性的微球,由于疏水相互作用的强化以及较长连接臂导致较小的空间位阻,使其对胆红素的吸附能力明显高于多乙烯多胺改性的微球.

The crosslinking microspheres of poly （glycidyl methacrylate） （PGMA） were modified chemically with aminating agents, hexanediamine and three kinds of multi-ethylene multi-amine. The effects of various factors, such as the chemical structures of the aminating agents, pH values of the medium, ionic strength, and temperature, on the adsorption property of the functional microsphers for bilirubin were examined. The adsorption mechanism of the aminated microspheres towards bilirubin was studied deeply. The experimental results showed that the aminated microspheres had strong adsorption ability for bilirubin and the adsorption capacity could reach 17.80 mg·g^-1; the isotherm adsorption could be fitted by Freundlich equation satisfactorily. There were three acting forces between the aminated microspheres and bilirubin molecules, i.e., electrostatic, hydrogen bonding and hydrophobic interactions. Among them, the electrostatic interaction was dominative, and the latter two kinds exert cooperating action. As pH=6, there was the strongest electrostatic interaction between the aminated microspheres and bilirubin molecules, leading to the highest adsorption capacity. The higher ionic strength was disadvantageous to the electrostatic interaction, and salinity conduces to the weakening of the electrostatic interaction and the decreasing of the adsorption capacity. The rising of temperature was advantageous to the hydrophobic interaction, whereas unfavorable to hydrogen bonding, and the predominated one of them dominates the effect of temperature on the adsorption capacity. The adsorption ability of the aminated microspheres modified with hexanediamine was stronger than that of those aminated microspheres modified with multi-ethylene multi-amine owing to enhancement of the hydrophobic interaction and smaller steric hindrance which came from longer spacer arm.