An assessment on the interaction of a hydrophilic ionic liquid with different sorbents

Ionic liquids have received an upsurge in interest as green solvents, primarily as replacements for conventional media in chemical processes. This growing interest may soon lead to their presence in the environment. To evaluate the environmental fate of ionic liquids, their sorption onto different media is an essential parameter. This study presents an experimental verification of the sorption of 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) onto different sorption media. The examined sorption media included two activated carbons (SPS-200 and SPC-100), an ion-exchange resin (IER), a fermentation waste (Corynebacterium glutamicum), and a dried activated sludge. Through HPLC and MS/MS analysis, [BMIM][Cl] was found to be stable only in the pH range 3 to 11. The experimental results reveal that removal of [BMIM][Cl] was only possible using IER and the two forms of activated carbon. The equilibrium solution pH was found to have no significant effect on the sorption ability of IER, whereas, both forms of activated carbon exhibited high sorption under strong alkaline conditions. No significant sorption of [BMIM] was observed with both C. glutamicum and the activated sludge. According to the Langmuir model, the IER can sorb as much as 179.4 mg [BMIM]/g, whereas those of SPS-200 and SPC-100 were 20.6 and 19.6 mg [BMIM]/g, respectively. The sorption kinetics was found to be rapid, with only 15 and 60 min required to attain equilibrium for IER and the two forms of activated carbon, respectively. Only IER exhibited significant sorption ability toward chloride ions which are an anionic part of the IL.