Study of adsorption of lipoic acid on three types of resin

摘要

Adsorption of lipoic acid on three different types resin was compared. Study on adsorption thermodynamics and kinetics of lipoic acid by XAD-4, NDA-100 and ND-90 resin was carried out through static experiments. The results show the polar groups and the micropores range on the resin play a significant role on adsorption of lipoic acid. These adsorption processes of lipoic acid are indicative of exothermic process and physical adsorption. The adsorption of lipoic acid on XAD-4 resin is Langmuir monolayer and the adsorption velocity appears to be the first order kinetics. The adsorption data of lipoic acid on NDA-100 and ND-90 resins also fit well to the Langmuir isotherm, which is caused by the capillary condensation and the volume filling of micropores besides monolayer adsorption. The adsorption of lipoic acid on NDA-100 and ND-90 resins passes through two phases: macropores and mesopores range and micropores range. And the adsorption velocities of the two phases are the first order kinetics.