LIQUID-LIQUID EQUILIBRIA DATA OF N-METHYL-2-HYDROXYETHYL AMMONIUM ALKYLATES WITH BUTANOL+WATER AND PENTANOL+WATER AT 293.15K, 313.15K AND 333.15K

Abstract Ionic liquids (ILs) are organic salts with low volatility and have different applications including organic synthesis, separation and extraction processes, fuel cell electrolyte, surfactants, among others. Protic ILs based on the N-methyl-2-hydroxyethyl ammonium cation and short chain carboxylic anions have simple synthesis and purification. However, as new substances few data are available for their thermodynamic properties and phase equilibria. In order to investigate the partition of these substances in alcohol-water, liquid-liquid equilibria data were determined experimentally for three ionic liquids (formed by the cation N-methyl-2-hydroxyethyl ammonium (m-2HEA) and the anions propionate (Pr), butanoate (B) and pentanoate (P)) with butanol and pentanol, at three different temperatures: 293.15K, 313.15K and 333.15K. The binodal curves are obtained by the turbidity method with gravimetric determination of all the components, curves are fitted using the Merchuk method. The tie-lines are also gravimetrically determined. The results confirm the high hydrophilicity of these ionic liquids, with partition coefficients of water-butanol and water-pentanol lower than 1. Data were correlated with UNIFAC.

摘要：离子液体（Ionic Liquids, ILs）是一类低挥发性有机盐，可用于有机合成、分离萃取工艺、燃料电池电解质、表面活性剂等诸多领域。基于N-甲基-2-羟乙基铵阳离子与短链羧酸根阴离子的质子型离子液体（Protic ILs）合成及纯化流程简便，但作为一类新型物质，其热力学性质与相平衡数据较为匮乏。为探究此类离子液体在醇-水体系中的分配行为，本文针对三种离子液体（由阳离子N-甲基-2-羟乙基铵（m-2HEA）与丙酸根（Pr）、丁酸根（B）、戊酸根（P）阴离子构成），分别在293.15K、313.15K及333.15K三个温度下，针对其与正丁醇、正戊醇构成的体系开展了液液平衡数据的实验测定。双结点曲线通过浊度法结合各组分重量分析法获得，并采用Merchuk法进行曲线拟合；结线数据同样通过重量分析法测定。实验结果证实了此类离子液体具有较高的亲水性，其水-丁醇与水-戊醇体系的分配系数均小于1。本文采用UNIFAC模型对实验数据进行了关联。