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Title: Extraction Selectivity of a Quaternary Alkylammonium Salt for Trivalent Actinides over Trivalent Lanthanides: Does Extractant Aggregation Play a Role?

In this paper, the extraction behavior of a quaternary alkylammonium salt extractant was investigated for its selectivity for trivalent actinides over trivalent lanthanides in nitrate and thiocyanate media. The selectivity was evaluated by solvent extraction experiments through radiochemical analysis of 241Am and 152/154Eu. Solvent extraction distribution and slope-analysis experiments were performed with americium(III) and europium(III) with respect to the ligand (nitrate and thiocyanate), extractant, and metal (europium only) concentrations. Further evaluation of the equilibrium expression that governs the extraction process indicated the appropriate use of the saturation method for estimation of the aggregation state of quaternary ammonium extractants in the organic phase. From the saturation method, we observed an average aggregation number of 5.4 ± 0.8 and 8.5 ± 0.9 monomers/aggregate for nitrate and thiocyanate, respectively. Through a side-by-side comparison of the nitrate and thiocyanate forms, we discuss the potential role of the aggregation in the increased selectivity for trivalent actinides over trivalent lanthanides in thiocyanate media.
Authors:
 [1] ;  [2] ;  [2]
  1. Univ. of Iowa, Iowa City, IA (United States)
  2. Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Solvent Extraction and Ion Exchange
Additional Journal Information:
Journal Volume: 35; Journal Issue: 4; Journal ID: ISSN 0736-6299
Publisher:
Taylor and Francis
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Chemical Sciences, Geosciences, and Biosciences Division
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Aliquat-336; americium; europium; separations; solvent extraction; thiocyanate
OSTI Identifier:
1389552