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Title: Surface complexation modeling of U(VI) sorption to Hanford sediment with varying geochemical conditions

Abstract

A series of U(VI) adsorption experiments with varying pH, ionic strength, concentrations of dissolved U(VI) and carbonate was conducted to provide a more realistic database for U(VI) adsorption onto near-field vadose zone sediments at the proposed Integrated Disposal Facility (IDF) on the Hanford Site. The distribution coefficient, Kd, for U(VI) in predicted “pure” glass leachate is 0 mL/g because the glass leachate has high sodium and carbonate concentrations and high pH. The zero adsorption result suggests that uranium will exhibit no retardation when the subsurface geochemistry is controlled by glass leachate. However, U(VI) can be sequestrated even when the pH, carbonate and sodium concentrations reached levels similar to “pure” glass leachate, because U(VI) coprecipitates with calcite. When glass leachate interacts with existing porewater or surrounding sediments, sorption is observed and the numerical value of the U(VI) Kd varies significantly. A non-electrostatic, general composite approach for surface complexation modeling was applied and a combination of two U(VI) surface species, monodentate (SOUO2+) and bidentate (SO2UO2(CO3)2-), simulated very well the measured U(VI) adsorption data. The general composite surface complexation model, compared to the constant or single-valued Kd model, more accurately predicted U(VI) adsorption under the varying geochemical conditions expected at the IDF.

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
985073
Report Number(s):
PNNL-SA-49960
Journal ID: ISSN 0013-936X; ISSN 1520-5851; 830403000; TRN: US1006071
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Science & Technology, 41(10):3587-3592; Journal Volume: 41; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ADSORPTION; CALCITE; CARBONATES; DISTRIBUTION; GEOCHEMISTRY; GLASS; LEACHATES; SEDIMENTS; SIMULATION; SODIUM; SORPTION; URANIUM; Uranium; Kd; isotherm; adsorption; IDF

Citation Formats

Um, Wooyong, Serne, R. Jeffrey, and Krupka, Kenneth M.. Surface complexation modeling of U(VI) sorption to Hanford sediment with varying geochemical conditions. United States: N. p., 2007. Web. doi:10.1021/es0616940.
Um, Wooyong, Serne, R. Jeffrey, & Krupka, Kenneth M.. Surface complexation modeling of U(VI) sorption to Hanford sediment with varying geochemical conditions. United States. doi:10.1021/es0616940.
Um, Wooyong, Serne, R. Jeffrey, and Krupka, Kenneth M.. Wed . "Surface complexation modeling of U(VI) sorption to Hanford sediment with varying geochemical conditions". United States. doi:10.1021/es0616940.
@article{osti_985073,
title = {Surface complexation modeling of U(VI) sorption to Hanford sediment with varying geochemical conditions},
author = {Um, Wooyong and Serne, R. Jeffrey and Krupka, Kenneth M.},
abstractNote = {A series of U(VI) adsorption experiments with varying pH, ionic strength, concentrations of dissolved U(VI) and carbonate was conducted to provide a more realistic database for U(VI) adsorption onto near-field vadose zone sediments at the proposed Integrated Disposal Facility (IDF) on the Hanford Site. The distribution coefficient, Kd, for U(VI) in predicted “pure” glass leachate is 0 mL/g because the glass leachate has high sodium and carbonate concentrations and high pH. The zero adsorption result suggests that uranium will exhibit no retardation when the subsurface geochemistry is controlled by glass leachate. However, U(VI) can be sequestrated even when the pH, carbonate and sodium concentrations reached levels similar to “pure” glass leachate, because U(VI) coprecipitates with calcite. When glass leachate interacts with existing porewater or surrounding sediments, sorption is observed and the numerical value of the U(VI) Kd varies significantly. A non-electrostatic, general composite approach for surface complexation modeling was applied and a combination of two U(VI) surface species, monodentate (SOUO2+) and bidentate (SO2UO2(CO3)2-), simulated very well the measured U(VI) adsorption data. The general composite surface complexation model, compared to the constant or single-valued Kd model, more accurately predicted U(VI) adsorption under the varying geochemical conditions expected at the IDF.},
doi = {10.1021/es0616940},
journal = {Environmental Science & Technology, 41(10):3587-3592},
number = 10,
volume = 41,
place = {United States},
year = {Wed Apr 11 00:00:00 EDT 2007},
month = {Wed Apr 11 00:00:00 EDT 2007}
}