Different ionic liquid modified hypercrosslinked polystyrene resin for purification of catechins from aqueous solution A Physicochemical and engineering aspects

A series of different ionic liquid modified hypercrosslinked polystyrene resins were prepared and evaluated for their adsorption properties where benzimidazole modified hypercrosslinked polystyrene resins exhibited best selectivity against catechins comparison with others ionic liquid modified hypercrosslinked resins and commercial resins. The maximum adsorption capacity of Benzimidazole/Hyper are up to 75.3mg/g for (−)-epigallocatechin gallate and 101.7mg/g for (−)-epicatechin. The pseudo-second-order kinetic equation and intra-particle diffusion model could describe the entire adsorption process of (−)-epigallocatechin gallate and (−)-epicatechin onto ionic liquid modified hypercrosslinked resins. Isothermal equilibrium curves showed a good fitness with the Langmuir and Freundlich models. Evaluated thermodynamic parameters revealed that adsorption was spontaneous and endothermic. The results from the sequential adsorption-desorption cycles showed that Benzimidazole/Hyper resins held good desorption and reusability. The adsorption mechanism was indicated to be the synergistic effect of molecular sieving effect, multiple adsorption interactions and specific surface area. In addition, the steric hindrance of ionic liquid functional group in the hypercrosslinked polymeric resins was a crucial factor for the order of the adsorption capacity.