Abstract: Extraction of Co2+ and Cd2+ into hydrophobic ionic liquids of [Bmim]PF6, [Hmim]PF6 and [Omim]PF6 is investigated for examining their removal from wastewater. The results indicate that the extraction rates of both Co2+ and Cd2+ are very low without chelator. However, the extraction rates are greatly enhanced from 2.06% to 96.37% for Co2+ and 1.82% to 93.68% for Cd2+ after the addition of chelator. The addition of different chelators also has a certain impact on the removal rates of heavy metal ions. The longer carbon bond the ionic liquids have, the better the extraction is. Similar to traditional solvent n-butanol, pH has a great impact on the removal rates of Co2+ and Cd2+. When pH<2, the extraction rates of Co2+ and Cd2+ are close to zero. While for pH>6, the extraction rates are above 90%. The pH swing effect is used to strip the heavy metal ions from ionic liquids, and the reuse of ionic liquids is realized.

Key words: ionic liquids, extraction, Co2+, Cd2+, wastewater

摘要： 研究了疏水性离子液体[Bmim]PF6(1-丁基-3-甲基咪唑六氟磷酸盐)、[Hmim]PF6(1-己基-3-甲基咪唑六氟磷酸盐)和[Omim]PF6(1-辛基-3-甲基咪唑六氟磷酸盐)对Co2+和Cd2+的萃取性能. 结果表明，未加入螯合剂时，离子液体对Co2+和Cd2+的萃取率都很低. 螯合剂的加入大大提高了离子液体对重金属离子的萃取性能，Co2+和Cd2+的萃取率分别由原来的2.06%和1.82%提高到96.37%和93.68%. 不同螯合剂对离子液体萃取Co2+和Cd2+有一定的影响. 离子液体碳链长度的增加有利于Co2+和Cd2+的萃取. 与传统有机溶剂相似，离子液体萃取重金属离子过程中具有很强的pH摆动效应，当pH<2时，Co2+和Cd2+的萃取率几乎为0，而当pH>6时，Co2+和Cd2+的萃取率均大于90%. 运用萃取过程中的pH摆动效应对Cd2+进行反萃取，实现了离子液体的回用.

关键词: 离子液体, 萃取, Co2+, Cd2+, 废水