Adsorption of Ionic Liquids from Cellulosic Hydrolysate by Ion-exchange Resin

Ionic liquids (ILs) have got wide applications as solvent or catalyst for the conversion of saccharides into valuable chemicals due to their fascinating properties. However, some ILs inevitably occur in separation difficulty from products in aqueous samples since they do have notable solubility in water. Meanwhile, it will bring about effluent discharges. Recently, the hydrolysis of cellulose in ionic liquids has been intensively investigated, but little is known about the ionic liquids removal from the hydrolysate. This study proposes adsorption by ion-exchange resin for the removal of ILs, involved in cellulosic hydrolysate. The ion- exchange resin of 732H with sulfonic acid functional group was applied to examine the sorption abilities for 1-butyl-3- methylimidazolium chloride ((Bmim)Cl), 1-propyl sulfonic acid-3-methylimidazolium hydrogensulfate ((C3SO3Hmim)HSO4) and benzothiazolium methanesulfonate ((HBth)CH3SO3). The results showed that the resin of 732H exhibits promising sorption abilities for (Bmim)Cl and (HBth)CH3SO3, while no sorption on (C3SO3Hmim)HSO4. The static desorption experiment of ionic liquids was investigated, the results indicated that 92.05% of (Bmim)Cl can be eluted from the (Bmim)Cl- loaded resin. Under the same elution conditions, 90.04% of (Bmim)Cl and 52.95% of (HBth)CH3SO3 can be eluted from the (Bmim)Cl·(HBth)CH3SO3-loaded resin. This study is expected to be helpful in the ILs recycling and the treatment of water pollution.