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Title: Stability Constants of Technetium (IV) Oxalate Complexes as a Function of Ionic Strength

Abstract

Solvent extraction methods were used to determine the stability constants of Tc(IV) with oxalate anions in NaCl solutions ranging in concentration from 0.5 M to 2.0 M. All experiments were conducted in an atmosphere-controlled chamber under Ar atmosphere (< 1.0ppm O2). A reducing agent (hydrazine) was used during extractions to maintain technetium in the tetravalent oxidation state. Independent tests confirmed that the oxidation state of technetium did not change during extractions. The distribution ratio of Tc(IV) between the organic and aqueous phases was found to decrease as the concentration of oxalic acid increased. At the oxalic acid concentrations used in these experiments, the complexes TcO(Ox) and TcO(Ox)22- were found to be the dominant aqueous species. Based on these data, the thermodynamic stability constants of Tc(IV) with oxalate complexes were calculated by the Specific Ion Interaction Theory (SIT).

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
881680
Report Number(s):
PNNL-SA-45795
Journal ID: ISSN 0033-8230; RAACAP; KP1302000; TRN: US0602969
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Radiochimica Acta, 94(3):137-141; Journal Volume: 94; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; TECHNETIUM COMPLEXES; OXALATES; REDUCING AGENTS; SOLVENT EXTRACTION; STABILITY; THERMODYNAMICS; VALENCE; Technetium (IV); Oxalate; Complexation; Stability constants; Solvent extraction; Specific Ionic Interaction Theory

Citation Formats

Xia, Yuanxian, Hess, Nancy J., and Felmy, Andrew R. Stability Constants of Technetium (IV) Oxalate Complexes as a Function of Ionic Strength. United States: N. p., 2006. Web. doi:10.1524/ract.2006.94.3.137.
Xia, Yuanxian, Hess, Nancy J., & Felmy, Andrew R. Stability Constants of Technetium (IV) Oxalate Complexes as a Function of Ionic Strength. United States. doi:10.1524/ract.2006.94.3.137.
Xia, Yuanxian, Hess, Nancy J., and Felmy, Andrew R. Wed . "Stability Constants of Technetium (IV) Oxalate Complexes as a Function of Ionic Strength". United States. doi:10.1524/ract.2006.94.3.137.
@article{osti_881680,
title = {Stability Constants of Technetium (IV) Oxalate Complexes as a Function of Ionic Strength},
author = {Xia, Yuanxian and Hess, Nancy J. and Felmy, Andrew R.},
abstractNote = {Solvent extraction methods were used to determine the stability constants of Tc(IV) with oxalate anions in NaCl solutions ranging in concentration from 0.5 M to 2.0 M. All experiments were conducted in an atmosphere-controlled chamber under Ar atmosphere (< 1.0ppm O2). A reducing agent (hydrazine) was used during extractions to maintain technetium in the tetravalent oxidation state. Independent tests confirmed that the oxidation state of technetium did not change during extractions. The distribution ratio of Tc(IV) between the organic and aqueous phases was found to decrease as the concentration of oxalic acid increased. At the oxalic acid concentrations used in these experiments, the complexes TcO(Ox) and TcO(Ox)22- were found to be the dominant aqueous species. Based on these data, the thermodynamic stability constants of Tc(IV) with oxalate complexes were calculated by the Specific Ion Interaction Theory (SIT).},
doi = {10.1524/ract.2006.94.3.137},
journal = {Radiochimica Acta, 94(3):137-141},
number = 3,
volume = 94,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2006},
month = {Wed Mar 01 00:00:00 EST 2006}
}