Synergistic Solvent Extraction of Trivalent Lanthanoids with Mixtures of 1‐Phenyl‐3‐methyl‐4‐pivaloyl‐5‐pyrazolone and Crown Ethers

Abstract

This paper embodies the results of the investigations carried out on the extraction behavior of lanthanoids such as Nd(III), Eu(III), and Tm(III) from perchlorate solutions into chloroform with 1‐phenyl‐3‐methyl‐4‐pivaloyl‐5‐pyrazolone (HPMPP) in the presence and absence of various crown ethers (CE), 18‐crown‐6 (18C6), dicyclohexano‐18‐crown‐6 (DC18C6), and dibenzo‐18‐crown‐6 (DB18C6). The results demonstrate that these trivalent metal ions are extracted into chloroform as Ln(PMPP)₃, with HPMPP alone, and in the presence of CE as Ln(PMPP)_3·CE. The equilibrium constants of the extracted complexes have been determined by nonlinear regression analysis and are found to increase monotonically with decreasing ionic radii of these metal ions. The addition of a CE to the metal chelate system not only enhances the extraction efficiency but also improves the selectivities among these trivalent lanthanoids, especially in the presence of DB18C6.

Keywords:

• Synergistic extraction
• Lanthanoids
• 4‐Acylpyrazolone
• Crown ethers

Acknowledgments

The authors wish to thank Dr. G. D. Surender, Head, Process Science and Engineering Division and The Director, Regional Research Laboratory, Trivandrum, for their constant encouragement. One of the authors (R.P) wishes to thank the Council of Scientific & Industrial Research for the award of Junior Research Fellowship. Financial support from the Board of Research in Nuclear Sciences is also acknowledged.