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Int. J. Mol. Sci. 2013, 14(11), 21353-21377; doi:10.3390/ijms141121353
Article

Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System

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Received: 27 August 2013; in revised form: 7 October 2013 / Accepted: 18 October 2013 / Published: 28 October 2013
(This article belongs to the Special Issue Ionic Liquids 2014 & Selected Papers from ILMAT 2013)
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Abstract: Several fundamental extraction parameters such as the kinetics and loading were studied for a new type of metal solvent extraction system with ionic liquids. The binary mixture of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water shows thermomorphic behavior with an upper critical solution temperature (UCST), which can be used to avoid the slower mass transfer due to the generally higher viscosity of ionic liquids. A less viscous homogeneous phase and mixing on a molecular scale are obtained when the mixture is heated up above 55 °C. The influence of the temperature, the heating and cooling times, were studied for the extraction of neodymium(III) with betaine. A plausible and equal extraction mechanism is proposed in bis(trifluoromethylsulfonyl)imide, nitrate, and chloride media. After stripping of the metals from the ionic liquid phase, a higher recovery of the ionic liquid was obtained by salting-out of the ionic liquid fraction lost by dissolution in the aqueous phase. The change of the upper critical solution temperature by the addition of HCl or betaine was investigated. In addition, the viscosity was measured below and above the UCST as a function of the temperature.
Keywords: hydrometallurgy; ionic liquids; lanthanides; neodymium; phase transitions; rare earths; solvent extraction; thermomorphic behavior; UCST hydrometallurgy; ionic liquids; lanthanides; neodymium; phase transitions; rare earths; solvent extraction; thermomorphic behavior; UCST
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Vander Hoogerstraete, T.; Onghena, B.; Binnemans, K. Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System. Int. J. Mol. Sci. 2013, 14, 21353-21377.

AMA Style

Vander Hoogerstraete T, Onghena B, Binnemans K. Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System. International Journal of Molecular Sciences. 2013; 14(11):21353-21377.

Chicago/Turabian Style

Vander Hoogerstraete, Tom; Onghena, Bieke; Binnemans, Koen. 2013. "Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System." Int. J. Mol. Sci. 14, no. 11: 21353-21377.



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