Extraction of Co2+ and Cd2+ from Wastewater Using Hydrophobic Ionic Liquids as Solvents
疏水性离子液体为溶剂对Co2+和Cd2+废水的萃取性能

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.