Toward greener separations of rare earths: Bifunctional ionic liquid extractants in biodiesel

Authors

  • Yinghui Liu,

    1. State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625, Renmin Street, Changchun 130022, PR China
    2. Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China
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  • Lili Zhu,

    1. State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625, Renmin Street, Changchun 130022, PR China
    2. Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China
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  • Xiaoqi Sun,

    1. State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625, Renmin Street, Changchun 130022, PR China
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  • Ji Chen

    Corresponding author
    1. State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625, Renmin Street, Changchun 130022, PR China
    • State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625, Renmin Street, Changchun 130022, PR China
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Abstract

Ionic liquids (ILs) containing quaternary phosphonium cations and phosphonic acid anions were explored as novel extractants for rare earths (RE) separation. They were considered to be bifunctional ionic liquid extractants (bif-ILEs), since both cations and anions of ILs were involved in the extraction. Trihexyl(tetradecyl)phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL 104), as a bif-ILE, together with propylene carbonate (PC), dimethyl carbonate (DMC), and soybean oil methyl ester (SBME, biodiesel) as diluents was employed in the extraction of RE(III) from aqueous solutions. Acidified Cyphos IL 104 (HNO3-Cyphos IL 104) exhibited high solubility in three diluents, and higher extraction efficiency than bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) because of the coextraction of RE(III) by quaternary phosphonium cation and phosphonic acid anion in organic phase. Additionally, this coextraction mechanism could eliminate the loss of IL. The physical properties and miscibility test results indicated that SBME was an excellent solvent for RE(III) extraction. © 2010 American Institute of Chemical Engineers AIChE J, 2010

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