An Aqueous Thermodynamic Model for the Complexation of Sodium and Strontium with Organic Chelators valid to High Ionic Strength. II. N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid (HEDTA)
This is the second paper in a two part series on the development of aqueous thermodynamic models for the complexation of Na+ and Sr2+ with organic chelators. In this paper the development of an aqueous thermodynamic model describing the effects of ionic strength, carbonate concentration, and temperature on the complexation of Sr2+ by HEDTA under basic conditions is presented. The thermodynamic model describing the Na+ interactions with the HEDTA3- chelate relies solely on the use of Pitzer ion-interaction parameters. The exclusive use of Pitzer ion-interaction parameters differs significantly from our previous model for EDTA, which required the introduction of a NaEDTA3- ion pair. Estimation of the Pitzer ion-interaction parameters for HEDTA3- and SrHEDTA- with Na+ allows the extrapolation of a standard state equilibrium constant for the SrHEDTA- species which is one order of magnitude greater than the 0.1M reference state value available in the literature. The overall model is developed from data available in the literature on apparent equilibrium constants for HEDTA protonation, the solubility of salts in concentrated HEDTA solutions, and from new data on the solubility of SrCO3(c) obtained as part of this study. The predictions of the final thermodynamic model for the Na-Sr-OH-CO3-NO3-HEDTA-H2O system are tested by application to chemical systems containing competing metal ions (i.e., Ca2+).
- Research Organization:
- Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Laboratory (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15003807
- Report Number(s):
- PNNL-SA-37212; JSLCAG; 4591; KP1301020; TRN: US201015%%112
- Journal Information:
- Journal of Solution Chemistry, Vol. 32, Issue 4; Other Information: PBD: 1 Apr 2003; ISSN 0095-9782
- Country of Publication:
- United States
- Language:
- English
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