Use of ion-exchange resins for the adsorption of the cationic part of ionic liquid, 1-ethyl-3-methylimidazolium

Ionic liquids (ILs) are low melting organic salts with wide potential applications due to their fascinating properties and have emerged as promising green replacements for volatile organic solvents. Despite their non-measurable vapor pressure, some ILs inevitably occur in effluent discharges since they do have significant solubility in water. Recently, the toxic effects of ILs toward aquatic communities have been intensively investigated, but little is known about their removal from industrial wastewater. This study proposes adsorption by ion-exchange resins for the removal of the cationic part of the IL, 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc). Twelve ion-exchange resins with different functional groups like thiourea, iminodiacetic acid, aminophosphonic acid, carboxylic acid, and sulfonic acid were examined. The resins with sulfonic acid functional groups showed the highest sorption abilities ranging from 578.2 to 616.2 mg/g. Large bead size led to lower kinetics of [EMIM] adsorption. But the bead size and the degree of cross-linking of the resins insignificantly affected the sorption performance of [EMIM] cations. (C) 2012 Elsevier B.V. All rights reserved.