Evaluation on the adsorption capability of chemically modified macroporous adsorption resin with ionic liquid

This paper describes ionic liquid-based macroporous adsorption resin (ionic liquid/MAR) as an adsorbent. (-)-Epicatechin gallate and (-)-epigallocatechin were selected as model compounds to evaluate the adsorption properties of the resin. Batch adsorption experiments were performed to measure both adsorption equilibrium and kinetics. The adsorption equilibrium capacities of(-)-epicatechin gallate and (-)-epigallocatechin on the ionic liquid/MAR at 298 K were 44.1 and 42.6 mg/g, respectively. These capacities increased with AB-8 (38.2 and 37.4 mg/g) and chloromethyl/MAR (38.1 and 20.0 mg/g) under similar conditions. Experimental data indicated a good fit with the pseudo-second-order model (R-2 >0.99), whereas adsorption isotherms fitted well with the Langmuir equation. The calculated Gibbs free energy, enthalpy, and entropy during adsorption revealed spontaneous and exothermic adsorption processes. A comparison of the adsorption behaviors of ionic liquid/MAR for (-)-epicatechin gallate and (-)epigallocatechin suggested that multiple adsorption interactions were primarily responsible for the observed adsorption. In addition, the adsorption capacity confirmed the feasible use of ionic liquid/MAR as a potential adsorbent for the adsorption and purification of catechins from herbal plants. (C) 2015 Elsevier B.V. All rights reserved.