向水相中加入有机物或盐, 在一定组成范围内, 可以形成密度不同的两相, 即双水相, 目前在生物萃取领域有广泛的应用。离子液体/表面活性剂体系的双水相体系符合绿色化学的要求, 而且目前研究尚不多见。采用离子液体四丁基膦氯化铁盐、十四烷基三丁基膦氯化铁盐（[P4444]FeCl₄、[P44414]FeCl₄）和两种表面活性剂十二烷基硫酸钠、十二烷基苯磺酸钠（SDS、SDBS）及柠檬酸钠混合形成双水相体系, 并绘制了[P4444]FeCl₄（[P44414]FeCl₄）/SDS（SDBS）/盐4个体系的相图, 用粒度测试研究发现, 双水相的上相粒度约为60~80 nm, 下相粒度太小而未能检测出来。使用紫外-可见分光光度法研究了双水相体系对不同性质染料的萃取效果。结果表明, 离子液体的疏水链长度和表面活性剂疏水链上存在苯环与否都对体系中双水相的区域产生影响。4个双水相体系都对水溶性染料有很好的萃取作用, 但是对油溶性染料萃取效果不佳。此项研究促进了离子液体在化学分离领域的开发利用。

Dyes are the most commonly used raw materials in the leather and textile industries, thereinto, printing and dyeing waste water has the characteristics of large amount, high content of organic pollutants, deep chroma, large alkalinity and large changes in water quality, which is difficult to treat.Therefore, it is of great significance to study the extraction and separation of dyes.Solvent extraction is one of the effective methods to purify printing and dyeing waste water.Ionic liquid aqueous two phase system can be used for extraction and separation of substances.The aqueous two phase system of ionic liquid/surfactant system meets the requirements of green chemistry and the research is rare at present.The ionic liquid of tetrabutylphosphonate ferric chloride and tetradecyltributylphosphine ferric chloride（[P4444]FeCl₄, [P44414]FeCl₄） and two surfactants of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate（SDS, SDBS） and sodium citrate were mixed to form an aqueous two phase system.The phase diagram of[P4444] FeCl₄（[P44414] FeCl₄）/SDS（SDBS）/salt system was drawn.It was found that the particle size of the upper phase was about 60~80 nm, and the particle size of the lower phase was too small to be detected.The effects of aqueous two phase system on the extraction of dyes with different properties were studied by UV-vis spec trophotometry.The results showed that the length of hydrophobic chain of ionic liquid and the presence of benzene ring on the hydrophobic chain of surfactant affected the region of aqueous two phase system.The four aqueous two phase systems had good extraction performance on water soluble dyes but the extraction performance on oil soluble dyes was not good.This study promotes the development and utilization of ionic liquids in chemical separation region.