咪唑类[PF_6]^-型离子液体萃取胺类化合物

Extraction of amine compounds with imidazoles ionic liquid of [PF_6]^-

以咪唑类[PF6]-型离子液体1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])、1-己基-3-甲基咪唑六氟磷酸盐([Hmim][PF6])和1-辛基-3-甲基咪唑六氟磷酸盐([Omim][PF6])对苯胺、对氯苯胺等7种胺类化合物的萃取,考察了溶液初始浓度、相比、盐类、pH及离子液体咪唑基团上取代烷基对萃取平衡的影响,并研究了萃取过程的热效应。实验结果表明:溶液初始浓度对分配系数影响较小;相比10∶1是离子液体对胺类化合物的溶解饱和临界点,当相比大于10∶1时,分配系数降低;NaCl、K2SO4可以增大萃取分配系数,ZnSO4对分配系数几乎没有影响;pH增加,分配系数增大;离子液体对不同取代基的胺类萃取能力有较大的差异,咪唑基团上取代烷基的长度对不同胺类物质的分配系数影响较显著;萃取过程属于焓增大的吸热过程。

Ionic liquids with room temperature[ Bmim ] [ PF6 ] , [ Hmim ] [ PF6 ] and [ Omim ] [ PF6 ] which are based on imidazoles ionic liquid of [ PF6 ] - are selected as extractants to extract seven kinds of amine compounds respectively from aqueous solution such as aniline, p-chloroaniline. The effects of initial concentration of aqueous solvent, phase ratio, added salt, pH and the substituted alkyl chain on the imidazole of ionic liquids on the extraction equilibrium were investigated and the heating effect of extraction process was also studied. The results showed that the effect of the initial concentration on distribution coefficient distribution coefficient D was little. When phase ratio was 10： 1, the dissolution of amine compounds in ionic liquids reached the saturated critical point, above which distribution coefficient decreased with the increasing phase ratio. The addition of NaCl and KESQ exerted a positive effect while ZnSO4 had almost no influence on the extraction equilibrium. The distribution coefficient D increased when pH value elevated. There was great difference in the extraction power on different amine compounds, and the influence of the length of alkyl chain on imidazole groups of the ionic liquids on distribution coefficients of amine compounds was significant. The extraction process was endothermic because the enthalpy increased in experiments.