Separation of polyprenols from Ginkgo biloba leaves by a nano silica-based adsorbent containing silver ions

Polyprenols extracted from Ginkgo biloba leaves is a kinds of unsaturated compound containing double bonds. Traditionally, the separation methods for the polyprenols are lack of selectivity and their separation efficiency are low. We synthesized two kinds of functional nano-silica containing silver ions materials (AgTCM and AgTCN) which have selectivity for unsaturated compounds to separate Ginkgo biloba leaves polyprenols for the first time. AgTCN displays exceptionally high selectivity for polyprenols and high stability under extended heat and light exposure, while silver is virtually immobile during solvent elution. Importantly, the exceptional stability of AgTCN gives rise to much higher polyprenols recovery than conventional silica gel during the chromatographic elution. In addition, we found that the adsorption of polyprenols onto the AgTCN conforms to pseudo-second-order kinetic model and AgTCN has strong affinity with polyprenols by analyzing Langmuir, Freundlich, Temkin-Pyzhev, and Dubinin-Radushkevich isotherms. The calculation results of thermodynamic parameters demonstrate that decrease of temperature in favor of increasing the adsorbing capacity of polyprenols onto the AgTCN, and the adsorption process of which is exothermic reaction. Our results pave the way for the novel separation methods of polyprenols from Ginkgo biloba leaves.