Abstract: 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(ΔH) at varied adsorption capacities(Q_e) 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 polysaccharide 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 polysaccharide 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 NaCl 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.

Key words: Equisetum ramosissimum Desf., polysaccharide, adsorption characteristics, adsorption mechanism, macroporous resin