Effect of the ionic liquid group in novel interpenetrating polymer networks on the adsorption properties for oleuropein from aqueous solutions

Abstract

By combining the advantages of ionic liquids with those of interpenetrating polymer networks, a novel ionic liquid modified adsorbent with a structure of an interpenetrating polymer network (PS/PVIm) was prepared and then used to enrich oleuropein to investigate the interactive forces between the adsorbent and oleuropein. The effects of contact time, initial concentration and temperature on the adsorption behaviour were systematically studied. The results of a static adsorption experiment showed that the adsorption process of the original resin (PS–CH₂Cl) for oleuropein obeyed a pseudo-second-order kinetic model, whereas that of the PS/PVIm towards oleuropein could be well depicted by pseudo-first-order and pseudo-second-order kinetic models, indicating the different adsorption behaviours of both the adsorbents. The Freundlich isotherm model could reasonably depict the adsorption process. Adsorption thermodynamics analysis indicated that the adsorption process was spontaneous and feasible. A dynamic adsorption and desorption experiment further validated the high affinity of PS/PVIm for oleuropein and the introduction of an ionic liquid imidazolium group and interpenetration polymer network can improve the adsorption efficiency. However, the adsorption rate decreased. The results of the present study have a significant importance in designing and preparing appropriate resins with ionic liquids and high adsorption efficiency to enrich oleuropein from olive leaves extract.