Enhancement of bio-oil derived chemicals in aqueous phase using ionic liquids: Experimental and COSMO-SAC predictions using a modified hydrogen bonding expression

Abstract

In this work the commercial hydrophobic imidazolium based ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TF2N]) was investigated for the extraction of acetic acid and furfural from aqueous solution. The liquid–liquid equilibrium (LLE) data for the ternary mixture of [BMIM][TF2N] (1)+acetic acid (2)+water (3) and [BMIM][TF2N] (1)+furfural (2)+water (3) were experimentally determined at T=298.15K and atmospheric pressure. The two phase region for acetic acid system was smaller as compared to the furfural system. The distribution co-efficient and selectivity values were greater than unity which indicates easier extraction of acetic acid and furfural from aqueous phase. The selectivity values for furfural were of two orders of magnitude greater than acetic acid. The experimental results were then correlated with the thermodynamic activity coefficient models namely NRTL and UNIQUAC models. The root mean square deviation (RMSD) obtained in NRTL and UNIQUAC models for both the systems were in the range of 0.26–0.75%. Thereafter a continuous probability distribution function for screening charge density has been used to obtain the interaction due to the hydrogen bonding term in conductor like screening model-segment activity coefficient (COSMO-SAC). This implementation gave RMSD values of 2.9% and 2.2% for IL–acetic acid–water and IL–furfural–water systems, respectively.