疏水性离子液体萃取氯酚类物质

Extraction of chlorophenols with imidazole-based hydrophobic ionic liquids

为了研究离子液体对环境水体中氯酚类物质的萃取性能,以治理氯酚类污染物。制备了1-辛基-3-甲基咪唑六氟磷酸盐([Omim]PF6)和1-辛基-3-甲基咪唑氟硼酸盐([Omim]BF4)两种疏水性离子液体。以超声波辅助萃取的方法,研究了离子液体对2-氯苯酚(2-CP)、4-氯苯酚(4-CP)、2,4-二氯苯酚(2,4-DCP)和2,4,6-三氯苯酚(2,4,6-TCP)等化合物的萃取性能。考察了温度、时间、相比(VIL:VCP)以及溶液p H等因素对萃取效果的影响,并对离子液体的重复使用性能进行了探讨。结果表明,温度与相比对萃取效果影响显著。两种离子液体对氯酚均显示出良好的萃取性能。在308 K,当相比(VIL:VCP)为1:3,溶液p H=3,萃取10 min的条件下,[Omim]BF4对2-CP、4-CP、2,4-DCP和2,4,6-TCP的萃取率分别为97.60%、95.20%、99.40%和87.20%;而以[Omim]PF6为溶剂,对氯酚的萃取率依次为95.80%、92.20%、98.20%和85.40%。研究发现,与磁力搅拌萃取方法不同,超声波辅助萃取的方法,随温度升高离子液体对氯酚类物质的萃取率增大。

1-Octyl-3- methyl imidazole hexafluorophosphate ([Omim]PF6) and 1-octyl-3-methyl imidazole tetrafluoroborate ([Omim]BF4) have been synthesized. Using 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol as reactants, Ultraviolet spectrum analysis (USA) as test method, ultrasonic oscillation as extraction method, the performance of extraction to different chlorophenols, the impact on extraction ratio by extraction temperature, time, phase ratio(VIL:VCP) and pH have been studied and the performance of reuse has also been discussed in this paper. It is concluded that the ionic liquids achieve the best condition with 15min, 1:3(VIL:VCP) phase ratio, 308 K andpH<5. Under the best condition, the extraction rates of [Omim]BF4 to 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol,2,4,6-trichlorophenol are 97.60%,95.20%,99.40% and 87.20%, respectively. For [Omim]PF6, however, the extraction rates are 95.80%,92.20%,98.20% and 85.40%. The mechanism of extraction is also discussed in this essay. It is also showed that the extraction rate is rising with the increase of temperature by ultrasonic oscillation, which is different with magnetic stirring method.