Synergistic extraction of rare earths(III) from chloride medium with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 and di-(2-ethylhexyl)-2-ethylhexylphosphonate

✍ Scribed by Junmei Zhao; Shulan Meng; Deqian Li

• Publisher: Wiley (John Wiley & Sons)
• Year: 2006
• Tongue: English
• Weight: 155 KB
• Volume: 81
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/jctb.1572

✦ Synopsis

Abstract

The synergistic effect of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 (HPMBP, HA) and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate (DEHEHP, B) in the extraction of rare earths (RE) from chloride solutions has been investigated. Under the experimental conditions used, there was no detectable extraction when DEHEHP was used as a single extractant while the amount of RE(III) extracted by HPMBP alone was also low. But mixtures of the two extractants at a certain ratio had very high extractability for all the RE(III). For example, the synergistic enhancement coefficient was calculated to be 9.35 for Y^3+^, and taking Yb^3+^ and Y^3+^ as examples, RE^3+^ is extracted as RE(OH)A~2~.B. The stoichiometry, extraction constants and thermodynamic functions such as Gibbs free energy change Δ__G__ (−17.06 kJ mol^−1^), enthalpy change Δ__H__ (−35.08 kJ mol^−1^) and entropy change Δ__S__ (−60.47 J K^−1^ mol^−1^) for Y^3+^ at 298 K were determined. The separation factors (SF) for adjacent pairs of rare earths were calculated. Studies show that the binary extraction system not only enhances the extraction efficiency of RE(III) but also improves the selectivity, especially between La(III) and the other rare earth elements. Copyright © 2006 Society of Chemical Industry