聚丙烯酸水凝胶对氯化-1-丁基-3-甲基咪唑离子液体的吸附热力学和动力学研究

Thermodynamic and kinetic studies of adsorption of 1-butyl-3-methylimidazole chloride ionic liquid onto PAA hydrogel

通过水溶液聚合法制备了聚丙烯酸水凝胶(polyacrylic acid,PAA),研究了溶液酸碱度和温度对聚丙烯酸水凝胶吸附氯化1-丁基3-甲基咪唑离子液体的影响。结果表明,水凝胶对氯化1-丁基3-甲基咪唑离子液体的吸附量随溶液pH值增大而逐渐增大,pH=2～4时增幅明显,而pH大于4时变化趋于缓慢;随温度的升高而逐渐降低。该等温吸附行为基本符合Langmuir吸附等温式,由二级吸附动力学模型获得的吸附过程活化能(Ea=52.470 kJ/mol)可以看出,PAA对氯化1-丁基3-甲基咪唑的吸附属于化学吸附范畴。

A super absorbent of PAA hydrogel was prepared by solution polymerization method.The pH value and the temperature of solution had an effect on the adsorption of 1-butyl-3-methylimidazole chloride ionic liquid onto PAA hydrogel.The results showed that the adsorption capacities of 1-butyl-3-methylimidazole chloride ionic liquid increased with increasing pH value.When pH=2~4,the adsorption capacities increased significantly,while pH was 4,it increased slowly with increase of pH.The adsorption capacities of ionic liquid decreased with increasing temperature.The adsorption behavior of 1-butyl-3-methylimidazole chloride could be described reasonably well by Langmuir isotherm.Chemical adsorption may be inferred by the activation energy Ea（Ea=52.470 kJ/mol）of adsorption obtained from the pseudo-second-order kinetic model.