Abstract
A new approach was suggested in present work for improving the separation between Pr(III) and Nd(III) by a so-called kinetic “push and pull” system consisting of [A336][NO3] and DTPA in a column extractor. It is revealed that, when organic extractant [A336][NO3] is continuously pumped into the column extractor in the form of dispersed oil droplets and at the same time DTPA was injected into the aqueous feed solution when the extraction was just started, the separation factor of Pr(III) to Nd(III), βPr/Nd, increased obviously with the time, and could even achieve 21.7. Such an amazing increase in βPr/Nd value might be due to the extraction rate of Pr(III) by [A336][NO3] oil droplets being faster than that of Nd(III), while the complexing rate of Nd(III) with DTPA in the aqueous solutions being faster than that of Pr(III). The opposite order of the two rates for Pr(III) and Nd(III) result in their kinetic “push and pull” separation. In contrast, the βPr/Nd value in traditional thermodynamic separation reported in previous literatures is only around 5 or even less, even though using the same extractant [A336][NO3] and DTPA but by previously adding DTPA into the aqueous feed solutions for pre-complexing of Pr(III) and Nd(III). Various effects from the pH and addition amount of DTPA aqueous solutions, LiNO3 concentrations in initial aqueous feed solutions, the initial concentration ratios of Pr(III) to Nd(III) ions, the initial pH of aqueous feed solutions, and the concentrations of [A336][NO3] in organic phases, on the kinetic separation of Pr(III) and Nd(III) are discussed. The present work highlights a promising approach for separation of rare earths or other targets with extreme similarity in physicochemical properties.
Original language | English |
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Pages (from-to) | 203-212 |
Number of pages | 10 |
Journal | Journal of Rare Earths |
Volume | 38 |
Issue number | 2 |
DOIs | |
State | Published - Feb 2020 |
Externally published | Yes |
Funding
Foundation item: Project supported by the National Natural Science Foundation of China (51574213, 51074150), and the Key Project of Chinese National Programs for Fundamental Research and Development (973 Program) (2012CBA01203).
Funders | Funder number |
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Chinese National Programs for Fundamental Research and Development | 2012CBA01203 |
National Natural Science Foundation of China | 51574213, 51074150 |
Keywords
- DTPA
- Kinetic separation
- Neodymium
- Praseodymium
- Rare earths
- [A336][NO]