双硫腙-Bmim[PF6]对水中Pb^(2+)的萃取分离性能初探

Preliminary study on extraction and separation performances of dithizone-Bmim[PF6]for Pb^(2+)in water

采用双硫腙-离子液体1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])对水中Pb^(2+)的萃取性能进行了考察。探究了络合剂含量、萃取温度、料液相pH、萃取体系与水相体积比及干扰离子对Pb^(2+)萃取率的影响;此外,在最佳萃取条件下,进行了反萃剂的筛选,考察了反萃剂浓度及反萃温度对反萃率的影响。结果表明,在萃取温度为35℃、料液相pH为6、络合剂双硫腙含量(以离子液体的质量计,下同)为0.72%、萃取体系与水相体积比为1∶4的条件下,该萃取体系对水中Pb^(2+)的萃取率高达98.0%。Cu^(2+)、Zn^(2+)和Ni2+的共存对Pb^(2+)的萃取率影响较小,该体系适用于Pb^(2+)的选择性提取。在35℃下,采用1.00 mol/L HNO3溶液对负载萃取体系进行反萃,Pb^(2+)反萃率可达97.0%。最后,探讨了该萃取与反萃体系多次复用的传质效率变化趋势,发现3次萃取/反萃后该体系萃取率依然可达80.0%,反萃率为65.0%。

Extraction performances of Pb^(2+)in water were investigated by dithizone-ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate([Bmim][PF6]).The effects of complexing agent content,extraction temperature,pH of liquid phase,volume ratio of extraction system to water phase and interference ions on the extraction rate of Pb2+were studied.In addition,the stripping agent was screened under the optimal extraction conditions.The effects of stripping agent concentration and stripping temperature on the stripping rate were explored.The results showed that the extraction rate of Pb2+from water was as high as 98.0%under the optimal conditions of extraction temperature of 35℃,pH=6,complexing agent dithizone content(based on the mass of ionic liquid,the same below)of 0.72%,and volume ratio of extraction system to water phase of 1∶4.The coexistence of Cu^(2+),Zn^(2+)and Ni2+had little influence on the extraction rate of Pb^(2+),so this system was suitable for the selective extraction of Pb^(2+).When 1.00 mol/L HNO_(3)solution was used as stripping agent at 35℃,the stripping rate of Pb^(2+)was 97.0%.Finally,the trend of mass transfer efficiencies in the multiple reuse of the extraction/stripping system were investigated.It was found that the extraction rate and stripping rate of the system still reached 80.0%and 65.0%after three times of extraction and stripping.