Co-solvent effects for aromatic extraction with ionic liquids

This work tries to solve the current problems associated with ionic liquid (IL) mediated liquid-liquid extraction such as large viscosity and high cost. The performance of IL-solvent mixtures instead of pure ILs as extractant was systematically studied here. In this work we have separated benzene (aromatic component) from hexane (aliphatic component) by using the extractant IL-Acetonitrile. The quaternary LLE experiments i.e., IL(1)-Acetonitrile(2)-Benzene(3)-Hexane(4) was conducted at T=298.15 K and 1 bar pressure. 1-ethyl-3-methylimidazolium based ionic liquid coupled with the anions ethylsulphate [EtSO4] and Acetate [Ac] was used to separate benzene using the IL and acetonitrile as the solvent. It was found that for both the systems, the hexane composition in extract phase and the solvent composition in raffinate phase are nearly zero. This implies that a mixture of IL-Acetonitrile can be beneficial since it avoids cross-contamination which is usually a problem with conventional solvents. Although the selectivities are very high (similar to 150), the capacities are low. With respect to selectivity values [EMIM][Ac] seems to be a more economical choice of solvent in terms of cross contamination. Both the NRTL and UNIQUAC models gave RMSD's less than unity. (C) 2013 Elsevier B.V. All rights reserved.