Adsorption Thermodynamics and Kinetics of Lipoic Acid on Three Types of Resin

Study on adsorption thermodynamics and kinetics of Lipoic acid by NG-16, NDA-100 and ND-90 resin was carried out through static experiments. The results showed that the adsorption of Lipoic acid on NG-16 resin is Langmuir monolayer, and the adsorption rate appears to be the first order kinetics. The adsorption date of Lipoic acid on NDA-100 and ND-90 resin also were described well by the Langmuir isotherm, which was caused by the capillary condensation and the volume filling of micropores besides monolayer adsorption. When the concentration of Lipoic acid is higher than 400mg/L, the capillary condensation and the volume filling of micropores act the main part. The adsorption of Lipoic acid on NDA-100 and ND-90 resin pass through two phases: macropores, mespores area and micropores area. And the adsorptions in micropores area are described well by the Dubinin-Radushkevich isotherm. The adsorption rates of the two phases are the first order kinetics.