## Abstract

Infinite dilution partition coefficients of isomeric benzene derivatives in the [bmim][Tf_{2}N] (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide)-CO_{2} biphasic system were measured with a supercritical fluid chromatography technique at pressures of 6–15 MPa and at temperatures of 313–353 K. The partition coefficients of o-cresol were always larger than those of m and p-cresol, while those of o-xylene were always smaller than those of m and p-xylene for all temperatures and pressures. The partition coefficients of the solutes in the ionic liquid-CO_{2} systems were found to be in the order of their vapor pressure in accordance with previous reports. The partition coefficient data were correlated with the ePC-SAFT (electrolytes perturbed-chain statistical associating fluid theory) equations and with the empirical LSER (Linear Solvation Energy Relationship)-δ model. The overall average relative deviation (ARD) of the ePC-SAFT equation using interaction parameters between ionic liquid and solute as fitting parameters was 8.2% and compared well with the LSER-δ model (7.5%). In one approach to improve the prediction capability of the ePC-SAFT equation, literature data of infinite dilution activity coefficients of toluene in the [bmim][Tf_{2}N]-toluene biphasic system at atmospheric pressure were used to determine ePC-SAFT interaction parameters between [bmim][Tf_{2}N] and toluene. Although this approach improved the ePC-SAFT description of the [bmim][Tf_{2}N]–CO_{2}–toluene system, the correlation was qualitative at high pressure and can be attributed to CO_{2} in the liquid phase that affects [bmim][Tf_{2}N]-toluene interactions.

Original language | English |
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Pages (from-to) | 36-43 |

Number of pages | 8 |

Journal | Fluid Phase Equilibria |

Volume | 420 |

DOIs | |

Publication status | Published - 2016 |

## Keywords

- Equation of state
- Ionic liquid
- PC-SAFT
- Supercritical carbon dioxide

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