bmimPF6-DMF-水三元体系的液液相平衡测定

摘要

为得到含N,N-二甲基甲酰胺(DMF)废水中萃取回收DMF工艺所需的基础数据,用液液平衡釜常压下测定了1-丁基-3-甲基咪唑六氟磷酸盐([bmim][PF6)离子液体-DMF-H2O三元体系在283.15～323.15 K下的液液分层曲线和液液相平衡数据.在此基础上,考察了三元体系中DMF和[bmim][PF6]离子液体的含量以及温度对[bmim][PF6]的选择性系数的影响.实验结果表明,液液平衡相图中两相区面积随温度升高而减小；相同温度下,[bmim][PF6]的选择性系数随着三元体系中DMF的含量增加而减小,随着离子液体用量增加而增大；溶液组成一定时,[bmim][PF6]的选择性系数随着温度升高而减小；当DMF的含量大于10％时,温度对选择性系数影响不大；283.15 K,三元体系中DMF的质量分数为2.04％时,选择性系数可达33.62,[bmim][PF6]用于萃取分离水中的DMF可行.%In order to obtain the basic data for the recovery of N,N-dimethylformamide (DMF) from wastewater by extraction, the liquid-liquid delamination curves and liquid-liquid phase equilibrium data of the 1 -butyl-3-methylimidazoHum hexafluorophosphate ([bmimJfPFg]) ionic liquid-DMF-H2O ternary system were determined by using an equilibrium autoclave at 283.15 to 323.15 K and atmospheric pressure. The effects of the contents of DMF and [bmim][PF6] in the ternary system and the temperature on the selectivity coefficient of [bmim][PF6] were investigated. The results show that the area of two-phase in the liquid-liquid equilibrium phase diagram decreases with the increase of the temperature. The selectivity coefficient of [bmim] [PF6] decreases with the increase of the content of DMF in the ternary system and increases with the increase of the amount of ionic liquid at the same temperature. And when the composition of the solution keeps unchanged, the selectivity coefficient of [bmim] [PF6] decreases with the increase of temperature. However, the temperature has little effect on the selectivity coefficient when the content of DMF is more than 10%. The selectivity coefficient of [bmim] [PF6] could be up to 33.62 at 283.15 K when the mass fraction of DMF is 2.04%. The [bmim][PF6j could probably be used for the extraction of DMF from aqueous solution.