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Title: Complexation of U(VI) with 1-Hydroxyethane-1,1-diphosphonicAcid (HEDPA) in Acidic to Basic Solutions

Abstract

Complexation of U(VI) with 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) in acidic to basic solutions has been studied with multiple techniques. A number of 1:1 (UO{sub 2}H{sub 3}L), 1:2 (UO{sub 2}H{sub j}L{sub 2} where j = 4, 3, 2, 1, 0 and -1) and 2:2 ((UO{sub 2}){sub 2}H{sub j}L{sub 2} where j = 1, 0 and -1) complexes form, but the 1:2 complexes are the major species in a wide pH range. Thermodynamic parameters (formation constants, enthalpy and entropy of complexation) were determined by potentiometry and calorimetry. Data indicate that the complexation of U(VI) with HEDPA is exothermic, favored by the enthalpy of complexation. This is in contrast to the complexation of U(VI) with dicarboxylic acids in which the enthalpy term usually is unfavorable. Results from electrospray ionization mass spectrometry (ESI-MS) and {sup 31}P NMR have confirmed the presence of 1:1, 1:2 and 2:2 U(VI)-HEDPA complexes.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
913545
Report Number(s):
UCRL-JRNL-227502
Journal ID: ISSN 0020-1669; INOCAJ; TRN: US0800767
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry, n/a, n/a, April 18, 2007, pp. 2870-2876
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; 12 MANAGEMENT OF RADIOACTIVE WASTES AND NON-RACIOACTIVE WASTER FROM NUCLEAR FACILITIES; 54 ENVIRONMENTAL SCIENCES; CALORIMETRY; DICARBOXYLIC ACIDS; ENTHALPY; ENTROPY; IONIZATION; MASS SPECTROSCOPY; POTENTIOMETRY; THERMODYNAMICS

Citation Formats

Reed, W A, Rao, L, Zanonato, P, Garnov, A, Powell, B A, and Nash, K L. Complexation of U(VI) with 1-Hydroxyethane-1,1-diphosphonicAcid (HEDPA) in Acidic to Basic Solutions. United States: N. p., 2007. Web.
Reed, W A, Rao, L, Zanonato, P, Garnov, A, Powell, B A, & Nash, K L. Complexation of U(VI) with 1-Hydroxyethane-1,1-diphosphonicAcid (HEDPA) in Acidic to Basic Solutions. United States.
Reed, W A, Rao, L, Zanonato, P, Garnov, A, Powell, B A, and Nash, K L. Wed . "Complexation of U(VI) with 1-Hydroxyethane-1,1-diphosphonicAcid (HEDPA) in Acidic to Basic Solutions". United States. doi:. https://www.osti.gov/servlets/purl/913545.
@article{osti_913545,
title = {Complexation of U(VI) with 1-Hydroxyethane-1,1-diphosphonicAcid (HEDPA) in Acidic to Basic Solutions},
author = {Reed, W A and Rao, L and Zanonato, P and Garnov, A and Powell, B A and Nash, K L},
abstractNote = {Complexation of U(VI) with 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) in acidic to basic solutions has been studied with multiple techniques. A number of 1:1 (UO{sub 2}H{sub 3}L), 1:2 (UO{sub 2}H{sub j}L{sub 2} where j = 4, 3, 2, 1, 0 and -1) and 2:2 ((UO{sub 2}){sub 2}H{sub j}L{sub 2} where j = 1, 0 and -1) complexes form, but the 1:2 complexes are the major species in a wide pH range. Thermodynamic parameters (formation constants, enthalpy and entropy of complexation) were determined by potentiometry and calorimetry. Data indicate that the complexation of U(VI) with HEDPA is exothermic, favored by the enthalpy of complexation. This is in contrast to the complexation of U(VI) with dicarboxylic acids in which the enthalpy term usually is unfavorable. Results from electrospray ionization mass spectrometry (ESI-MS) and {sup 31}P NMR have confirmed the presence of 1:1, 1:2 and 2:2 U(VI)-HEDPA complexes.},
doi = {},
journal = {Inorganic Chemistry, n/a, n/a, April 18, 2007, pp. 2870-2876},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 24 00:00:00 EST 2007},
month = {Wed Jan 24 00:00:00 EST 2007}
}
  • No abstract prepared.
  • The effect of 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) on sorption of Np(V) and Pu(V) to synthetic boehmite ({gamma}-AlOOH) was examined a function of time and pH (between 4 to 11). Sorption of both elements in boehmite suspensions (1 M NaCl, 600 mg L{sup -1} boehmite) increased with increasing pH. Sorption edges for neptunium and plutonium occurred at approximately pH 8.0 and 6.6, respectively. After steady state partitioning was reached, HEDPA was added to the neptunium-boehmite and plutonium-boehmite suspensions. Neptunium and plutonium partitioning appears to be primarily affected by the formation of soluble Np:HEDPA and Pu:HEDPA complexes, the dissolution of boehmite promoted bymore » HEDPA, and the precipitation of Np:HEDPA and Pu:HEDPA colloids. The results are discussed in terms of applicability of HEDPA-promoted dissolution as a waste reduction method in the treatment of sludge phases contained within high-level nuclear waste storage tanks.« less
  • No abstract prepared.
  • Protonation and complexation of {alpha}-isosaccharinic acid with U(VI) and Fe(III) have been studied in acidic solutions at t=25 C and I=1.0 mol dm{sup -3} NaClO{sub 4}. From the potentiometric titrations, the protonation constant of the carboxylate group is calculated to be 3.65 {+-} 0.05 and the data are consistent with the presence of three and four successive mononuclear complexes for U(VI) and Fe(III), respectively. The formation constants of the complexes, log {beta}{sub j}for the reactions of M+L=ML{sub j} where j=1-3 for U(VI), j=1-4 for Fe(III) and L stands for isosaccharinate, are determined to be 2.91 {+-} 0.15 (UO{sub 2}L), 5.37more » {+-} 0.07 (UO{sub 2}L{sub 2}), 7.25 {+-} 0.18 (UO{sub 2}L{sub 3}), 5.06 {+-} 0.17 (FeL), 8.51 {+-} 0.15 (FeL{sub 2}), 11.00 {+-} 0.16 (FeL{sub 3}), and 12.99 {+-} 0.17 (FeL{sub 4}). From the calorimetric titrations, the enthalpy of protonation of the carboxylate group is determined to be -(7.94 {+-} 0.03)kJ mol{sup -1}, similar to that of other ?-hydroxycarboxylates. The enthalpies of complexation between U(VI) and isosaccharinate are quite small: {Delta} H{sub 1} = -(1.0 {+-} 1.0)kJ mol{sup -1}, {Delta} H{sub 2}=1.4 {+-} 1.8 kJ mol{sup -1} and {Delta} H{sub 3}=-(6.2 {+-} 3.0)kJ mol{sup -1}, typical of the interactions between carboxylates and hard-acid cations. The complexation between U(VI) and isosaccharinate is mainly entropy-driven. In comparison, the enthalpies of complexation for FeL{sub 3} and FeL{sub 4} are large and exothermic, contributing significantly to the stability of the complexes.« less