Sobota Marek, Dohnal Vladimír, Vrbka Pavel
Department of Physical Chemistry, Institute of Chemical Technology, Prague, Czech Republic.
J Phys Chem B. 2009 Apr 2;113(13):4323-32. doi: 10.1021/jp811041k.
Infinite dilution activity coefficients gamma(1)(infinity) and gas-liquid partition coefficients K(L) of 30 selected hydrocarbons, alcohols, ketones, ethers, esters, haloalkanes, nitrogen- and sulfur-containing compounds in the ionic liquid (IL) 1-ethyl-3-methylimidazolium nitrate [EMIM][NO(3)] were determined by gas-liquid chromatography at five temperatures in the range from 318.15 to 353.15 K. Relative contribution of adsorption at gas-liquid interphase to the overall solute retention, as examined by varying sample size and IL loading in the column, was found negligible. Partial molar excess enthalpies and entropies at infinite dilution were derived from the temperature dependence of the gamma(1)(infinity) values. The linear free energy relationship (LFER) solvation model was used to correlate successfully the KL values. The LFER correlation parameters and excess thermodynamic functions were analyzed to disclose molecular interactions operating between the IL and the individual solutes. In addition, the promising potential of [EMIM][NO(3)] for applications in solvent-aided separation processes was identified, the selectivities of [EMIM][NO(3)] for separation of aromatic hydrocarbons and thiophene from saturated hydrocarbons ranking among the highest ever observed with ILs or molecular solvents.
通过气液色谱法在318.15至353.15 K范围内的五个温度下，测定了30种选定的烃类、醇类、酮类、醚类、酯类、卤代烷类、含氮和含硫化合物在离子液体1-乙基-3-甲基咪唑硝酸盐[EMIM][NO₃]中的无限稀释活度系数γ₁(∞)和气液分配系数K(L)。通过改变柱中样品大小和离子液体负载量来考察气液相间吸附对整体溶质保留的相对贡献，发现其可忽略不计。从γ₁(∞)值的温度依赖性推导出无限稀释时的偏摩尔过量焓和熵。线性自由能关系（LFER）溶剂化模型成功地关联了K(L)值。分析了LFER相关参数和过量热力学函数，以揭示离子液体与各溶质之间的分子相互作用。此外，还确定了[EMIM][NO₃]在溶剂辅助分离过程中的应用潜力，[EMIM][NO₃]从饱和烃中分离芳烃和噻吩的选择性在离子液体或分子溶剂中是有史以来观察到的最高之一。
