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Title: Immobilization and exchange of perrhenate in sodalite and cancrinite

Abstract

Highly alkaline nuclear tank wastes containing key anionic contaminants have leaked into the subsurface at the U.S. Department of Energy's Hanford Site. Laboratory studies showed that when simulated caustic tank wastes contact subsurface sediments, mineral dissolution and precipitation result in feldspathoid formation. Feldspathoids are environmentally important for waste management and disposal purposes because of their purported potential to sequester contaminants of interest (e.g., 99TcO 4 -, 137Cs +, 90Sr 2+) into their structure. In this paper, we investigated the incorporation of perrhenate (ReO 4 -), a surrogate for TcO 4 -, in the presence of competing anions (X) including OH -, NO 2 -, NO 3 - and Cl - on feldspathoid formation and under conditions mimicking tank waste solution compositions. The resulting solids were characterized by their chemical composition, structure and morphology. Regardless of solution pH, sodalite formed in the presence of Cl - and NO 2 - whereas NO 3 - promoted either cancrinite formation in 16-mol OH -/kg (16 m) or mixed sodalite/cancrinite phases in 1-mol OH -/kg (1 m) solutions. In the presence of Cl -, NO 2 -, and NO 3 - less than 0.02 mol fraction of ReO 4 - was incorporated into themore » feldspathoid phase(s). Although, the NO 2-sodalite and mixed NO 3-cancrinite/sodalite phases incorporated significantly more ReO 4 - than NO 3-cancrinite or Cl-sodalite phases, the total ReO 4 - fraction was ~1% or less of the total sites. The ReO 4 - immobilized in ReO 4-sodalite, NO 2-sodalite, mixed NO 3-cancrinite/sodalite and NO 3-cancrinite was resistant to ion exchange with either NO 2 - or NO 3 -. Finally, the results imply that ReO 4 -, and thus by analogy 99TcO 4 -, does not compete well with smaller ions for incorporation into feldspathoids, but, once sequestered, is difficult to exchange.« less

Authors:
 [1];  [1];  [1];  [2]
  1. Washington State Univ., Pullman, WA (United States). Dept. of Crop and Soil Sciences
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Contributing Org.:
Washington State Univ., Pullman, WA (United States)
OSTI Identifier:
1265509
DOE Contract Number:  
AC05-00OR22725; PS02-09ER65075
Resource Type:
Journal Article
Journal Name:
Microporous and Mesoporous Materials
Additional Journal Information:
Journal Volume: 214; Journal ID: ISSN 1387-1811
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Feldspathoids; Anion selectivity; Perrhenate; Technetium-99; Ion exchange

Citation Formats

Dickson, Johnbull O., Harsh, James B., Flury, Markus, and Pierce, Eric M. Immobilization and exchange of perrhenate in sodalite and cancrinite. United States: N. p., 2015. Web. doi:10.1016/j.micromeso.2015.05.011.
Dickson, Johnbull O., Harsh, James B., Flury, Markus, & Pierce, Eric M. Immobilization and exchange of perrhenate in sodalite and cancrinite. United States. doi:10.1016/j.micromeso.2015.05.011.
Dickson, Johnbull O., Harsh, James B., Flury, Markus, and Pierce, Eric M. Wed . "Immobilization and exchange of perrhenate in sodalite and cancrinite". United States. doi:10.1016/j.micromeso.2015.05.011.
@article{osti_1265509,
title = {Immobilization and exchange of perrhenate in sodalite and cancrinite},
author = {Dickson, Johnbull O. and Harsh, James B. and Flury, Markus and Pierce, Eric M.},
abstractNote = {Highly alkaline nuclear tank wastes containing key anionic contaminants have leaked into the subsurface at the U.S. Department of Energy's Hanford Site. Laboratory studies showed that when simulated caustic tank wastes contact subsurface sediments, mineral dissolution and precipitation result in feldspathoid formation. Feldspathoids are environmentally important for waste management and disposal purposes because of their purported potential to sequester contaminants of interest (e.g., 99TcO4-, 137Cs+, 90Sr2+) into their structure. In this paper, we investigated the incorporation of perrhenate (ReO4-), a surrogate for TcO4-, in the presence of competing anions (X) including OH-, NO2-, NO3- and Cl- on feldspathoid formation and under conditions mimicking tank waste solution compositions. The resulting solids were characterized by their chemical composition, structure and morphology. Regardless of solution pH, sodalite formed in the presence of Cl- and NO2- whereas NO3- promoted either cancrinite formation in 16-mol OH-/kg (16 m) or mixed sodalite/cancrinite phases in 1-mol OH-/kg (1 m) solutions. In the presence of Cl-, NO2-, and NO3- less than 0.02 mol fraction of ReO4- was incorporated into the feldspathoid phase(s). Although, the NO2-sodalite and mixed NO3-cancrinite/sodalite phases incorporated significantly more ReO4- than NO3-cancrinite or Cl-sodalite phases, the total ReO4- fraction was ~1% or less of the total sites. The ReO4- immobilized in ReO4-sodalite, NO2-sodalite, mixed NO3-cancrinite/sodalite and NO3-cancrinite was resistant to ion exchange with either NO2- or NO3-. Finally, the results imply that ReO4-, and thus by analogy 99TcO4-, does not compete well with smaller ions for incorporation into feldspathoids, but, once sequestered, is difficult to exchange.},
doi = {10.1016/j.micromeso.2015.05.011},
journal = {Microporous and Mesoporous Materials},
issn = {1387-1811},
number = ,
volume = 214,
place = {United States},
year = {2015},
month = {5}
}