大孔吸附树脂对湘西节节草多糖的吸附特性及机理

Adsorption Characteristics and Mechanism of Macroporous Resin to Polysaccharide from Equisetum ramosissimum Desf.

从湘西节节草中提取多糖并用D-101大孔吸附树脂进行纯化,研究了树脂对多糖的吸附热力学及吸附动力学特性,探索了吸附及解吸附的最佳工艺条件。结果表明,不同吸附量下大孔吸附树脂对多糖的吸附焓变ΔH均为正值,且ΔH绝对值均小于临界值40 kJ/mol,表明树脂对节节草多糖的吸附为物理吸附过程,吸附模型可用Langmuir和Freundlich方程描述,吸附过程是一个吸热、熵增加过程,吸附动力学规律可用一级速率方程表示。D-101大孔吸附树脂对节节草多糖吸附的最佳条件为:上样液多糖质量浓度2.0 g/L、上样液体积与树脂10∶1(mL∶g)、pH值6.0、120次/min恒温振荡12 h,最大吸附率为59.51%;解吸附的最佳条件为:以0.2 mol/L的NaCl溶液为洗脱剂,洗脱剂体积与树脂20∶1(mL∶g),解吸率超过95%;纯化后多糖纯度为39.29%,是纯化前(8.42%)的4.67倍。

The polysaccharide was extracted from Equisetum ramosissimum Desf. and purified using D-101 macroporous resin. The thermodynamic and kinetics characteristics of E. ramosissimum, polysaccharide on D-101 resin were investigated. The optimal conditions of adsorption and eluting were studied in detail. The results showed that all of heat of adsorption （AH） at varied adsorption capacities （ Qe ） were positive and less than 40 kJ/mol of critical value. The adsorption was a physical adsorption process. The Langmuir and Freundish could well describe the isothermal adsorption of polysaceharide on D-101 macroporous resin. The value of the enthalpy, free energy and entropy indicated that the adsorption was an endothermic process. The data obtained from kinetic experiments could be well described using pseudo-first order rate model. The adsorption rate was 59.51% under optimal adsorption conditions of 2.0 g/L polysaecharide crude extracts, 10：1 of liquid to resin ratio （ mL： g） , pH 6.0, 120/min oscillation for 12 h at constant temperature. The desorption rate outstripped 95% under optimal eluting conditions of 0.2 mol/L NaC1 solution as eluant and 20：1 of eluant to resin ratio（ mL： g）. The percentage of polysaccharide in the purified sample reached 39.29% , being 4.67 times of that （8.42%） of the crude extract.