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Title: Iodine immobilization by silver-impregnated granular activated carbon in cementitious systems

Abstract

Silver (Ag)-based technologies are amongst the most common approaches to removing radioiodine from aqueous waste streams. As a result, a large worldwide inventory of radioactive AgI waste presently exits, which must be stabilized for final disposition. In this work, the efficacy of silver-impregnated granular activated carbon (Ag-GAC) to remove iodide (I -), iodate (IO 3 -) and organo-iodine (org-I) from cementitious leachate was examined. In addition, cementitious materials containing I-, IO 3 -, or org-I loaded Ag-GAC were characterized by iodine K-edge XANES and EXAFS to provide insight into iodine stability and speciation in these waste forms. The Ag-GAC was very effective at removing I- and org-I, but ineffective at removing IO 3 - from slag-free grout leachate under oxic conditions. I- or org-I removal was due to the formation of insoluble AgI(s) or Ag-org-I(s) on the Ag-GAC. When I--loaded Ag-GAC material was cured with slag-free and slag grouts, I - was released from AgI(s) to form a hydrated I - species. Conversely, when org-I loaded Ag-GAC material was cured in the two grout formulations, no change was observed in the iodine speciation, indicating the org-I species remained bound to the Ag. Because little IO 3 - was bound tomore » the Ag-GAC, it was not detectable in the grout. Thus, grout formulation and I speciation in the waste stream can significantly influence the effectiveness of the long-term disposal of radioiodine associated with Ag-GAC in grout waste forms.« less

Authors:
 [1];  [1];  [2];  [2];  [1];  [3];  [3];  [3];  [3];  [3]
  1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
  2. Univ. of Georgia, Aiken, SC (United States)
  3. Texas A & M Univ., Galveston, TX (United States)
Publication Date:
Research Org.:
Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Laboratory (SRNL)
Sponsoring Org.:
USDOE Office of Environmental Management (EM)
OSTI Identifier:
1561205
Alternate Identifier(s):
OSTI ID: 1543052
Report Number(s):
SRNL-STI-2019-00137
Journal ID: ISSN 0265-931X; TRN: US2000602
Grant/Contract Number:  
AC09-08SR22470; LDRD-2017-00005; EM0004381; AC09-96SR18500; AC02-06CH11357; DEFC09-07-SR22506
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Environmental Radioactivity
Additional Journal Information:
Journal Volume: 208-209; Journal Issue: C; Journal ID: ISSN 0265-931X
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; iodine speciation; cement; slag; immobilization; redox; silver-impregnated granulated activated carbon

Citation Formats

Li, Dien, Kaplan, Daniel I., Price, Kimberly A., Seaman, John C., Roberts, Kimberly, Xu, Chen, Lin, Peng, Xing, Wei, Schwehr, Kathleen, and Santschi, Peter H. Iodine immobilization by silver-impregnated granular activated carbon in cementitious systems. United States: N. p., 2019. Web. doi:10.1016/j.jenvrad.2019.106017.
Li, Dien, Kaplan, Daniel I., Price, Kimberly A., Seaman, John C., Roberts, Kimberly, Xu, Chen, Lin, Peng, Xing, Wei, Schwehr, Kathleen, & Santschi, Peter H. Iodine immobilization by silver-impregnated granular activated carbon in cementitious systems. United States. https://doi.org/10.1016/j.jenvrad.2019.106017
Li, Dien, Kaplan, Daniel I., Price, Kimberly A., Seaman, John C., Roberts, Kimberly, Xu, Chen, Lin, Peng, Xing, Wei, Schwehr, Kathleen, and Santschi, Peter H. Wed . "Iodine immobilization by silver-impregnated granular activated carbon in cementitious systems". United States. https://doi.org/10.1016/j.jenvrad.2019.106017. https://www.osti.gov/servlets/purl/1561205.
@article{osti_1561205,
title = {Iodine immobilization by silver-impregnated granular activated carbon in cementitious systems},
author = {Li, Dien and Kaplan, Daniel I. and Price, Kimberly A. and Seaman, John C. and Roberts, Kimberly and Xu, Chen and Lin, Peng and Xing, Wei and Schwehr, Kathleen and Santschi, Peter H.},
abstractNote = {Silver (Ag)-based technologies are amongst the most common approaches to removing radioiodine from aqueous waste streams. As a result, a large worldwide inventory of radioactive AgI waste presently exits, which must be stabilized for final disposition. In this work, the efficacy of silver-impregnated granular activated carbon (Ag-GAC) to remove iodide (I-), iodate (IO3-) and organo-iodine (org-I) from cementitious leachate was examined. In addition, cementitious materials containing I-, IO3-, or org-I loaded Ag-GAC were characterized by iodine K-edge XANES and EXAFS to provide insight into iodine stability and speciation in these waste forms. The Ag-GAC was very effective at removing I- and org-I, but ineffective at removing IO3- from slag-free grout leachate under oxic conditions. I- or org-I removal was due to the formation of insoluble AgI(s) or Ag-org-I(s) on the Ag-GAC. When I--loaded Ag-GAC material was cured with slag-free and slag grouts, I- was released from AgI(s) to form a hydrated I- species. Conversely, when org-I loaded Ag-GAC material was cured in the two grout formulations, no change was observed in the iodine speciation, indicating the org-I species remained bound to the Ag. Because little IO3- was bound to the Ag-GAC, it was not detectable in the grout. Thus, grout formulation and I speciation in the waste stream can significantly influence the effectiveness of the long-term disposal of radioiodine associated with Ag-GAC in grout waste forms.},
doi = {10.1016/j.jenvrad.2019.106017},
url = {https://www.osti.gov/biblio/1561205}, journal = {Journal of Environmental Radioactivity},
issn = {0265-931X},
number = C,
volume = 208-209,
place = {United States},
year = {2019},
month = {7}
}