Adsorption of flavonoids with glycosides: Design and synthesis of chitosan-functionalized microspheres

Poly(styrene–divinylbenzene) based adsorption resin have been widely used in the separation and purification of natural products. However, commercially available resin had lower adsorption capacity and poor selectivity. In order to improve the adsorption capacity and selectivity of poly(styrene–divinylbenzene), a kind of chitosan modified poly(styrene–divinylbenzene) was prepared by Friedel-Crafts reaction and used to adsorb flavonoids with glycosides from aqueous solution. More importantly, the adsorption isotherms of rutin onto these materials were more consistent with Freundlich isotherm model, and the adsorption kinetics followed pseudo second-order equation. That adsorption capacity of rutin onto these materials reached adsorption equilibrium at 240 min. The experiments showed that with the increase of concentration, the adsorption capacity gradually increased. The thermodynamics parameters indicated that the adsorption process of rutin onto PSDVB-CS was spontaneous and endothermic. It was found that the adsorption capacities of the PSDVB-CS for rutin and quercetin were 218.59 mg/g and 32.45 mg/g, respectively. Hydrogen bond, π–π interaction may be the driving forces of adsorption. The results offered a method to modify poly(styrene–divinylbenzene) with chitosan to separate and purify flavonoid with glycosides from natural plants.