双硫腙-Bmim[PF6]对水中铅离子的萃取分离性能初探

Preliminary study on extraction and separation performance of dithizone-Bmim[PF6] for Lead ion in Water

摘要:

采用双硫腙-离子液体[Bmim][PF6]（1-丁基-3-甲基咪唑六氟磷酸盐）对水中铅离子的萃取性能及反应条件展开了研究。主要探究了络合剂含量、萃取温度、料液相pH值及萃取体系与水相体积比对萃取效率的影响；此外，在最佳萃取率的前提条件下，进行了反萃剂的筛选，并考察了反萃温度及浓度对反萃效率的影响规律，继而获得最佳反萃条件。研究结果表明，在萃取温度为35 ℃、pH为6、络合剂双硫腙含量为0.5%（w/v）、萃取体系与水相体积比为 1:4 的萃取条件下，该萃取体系对水中铅离子的萃取率高达98.0 %。在35 ℃下，采用1mol/L HNO3对上述负载萃取体系进行反萃，反萃率可达97.0 %。最后，考察了该萃取与反萃体系多次复用的传质效率变化趋势，结果显示三次萃取/反萃后该体系萃取率依然可达80.0 %，反萃率为65.0 %。

Abstract:

In this study, the performance of lead extraction by dithizone-ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate ([Bmim][PF6]) was researched. Both the extraction and stripping conditions and efficiencies of separating lead ions from water were investigated, respectively. The influences of extraction temperature, complexing agent content, pH value of the liquid phase, the volume ratio of the extraction system to the water phase as well as interference ions on the extraction efficiency were studied. In addition, on the prerequisite of the optimal extraction rate, the screening of the stripping agent was carried out. Furthermore, the influences of the stripping concentration and operating temperature on the stripping efficiency were investigated, and finally, the best stripping conditions were obtained. The research results showed that at the extraction conditions of 35 ℃, pH 6, complexing agent dithizone content of 0.5% (w/v), extraction system and water phase volume ratio of 1/4, the extraction rate of lead ions from water is as high as 98.0 %. In this system, the addition of interference ions has less effect on the extraction rate of Pb2+, and it can be used for the extraction and separation of various metal ions in wastewater. At 35 ℃, using 1mol/L HNO3 as the stripping solution, the above-mentioned loaded extraction system was effectively extracted to a rate of 97.0 %. Finally, the mass transfer efficiencies of the multiple extraction/stripping were investigated. The results showed that the extraction rate of the system still reached 80.0 % after three times of extractions, and the stripping rate was 65.0 %