Immobilization and exchange of perrhenate in sodalite and cancrinite

Johnbull O. Dickson; James B. Harsh; Markus Flury; Eric M. Pierce

doi:10.1016/j.micromeso.2015.05.011

Immobilization and exchange of perrhenate in sodalite and cancrinite

Johnbull O. Dickson
, James B. Harsh
, Markus Flury
, Eric M. Pierce

Environmental Sciences Division

Research output: Contribution to journal › Article › peer-review

25 Scopus citations

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., ⁹⁹TcO₄^-, ¹³⁷Cs⁺, ⁹⁰Sr²⁺) into their structure. 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^-. 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.

Original language	English
Pages (from-to)	115-120
Number of pages	6
Journal	Microporous and Mesoporous Materials
Volume	214
DOIs	https://doi.org/10.1016/j.micromeso.2015.05.011
State	Published - May 28 2015

Funding

We thank the staff at the Franceschi Microscopy and Imaging Center at Washington State University for access to and assistance with the use of their SEM facilities. We also acknowledge the Mineralogical Society of America and the Bullitt Foundation for their support. This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science, Biological and Environmental Research, Subsurface Biogeochemical Research (SBR) Program , and was performed at Washington State University under contract No. DE-PS02-09ER65075 and at Oak Ridge National Laboratory under contract No. DE-AC05-00OR22725 . The authors thank the two anonymous reviewers for their comments.

Keywords

Anion selectivity
Feldspathoids
Ion exchange
Perrhenate
Technetium-99

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10.1016/j.micromeso.2015.05.011

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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., 99TcO4-, 137Cs+, 90Sr2+) into their structure. 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-. 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.",

keywords = "Anion selectivity, Feldspathoids, Ion exchange, Perrhenate, Technetium-99",

author = "Dickson, \{Johnbull O.\} and Harsh, \{James B.\} and Markus Flury and Pierce, \{Eric M.\}",

year = "2015",

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doi = "10.1016/j.micromeso.2015.05.011",

language = "English",

volume = "214",

pages = "115--120",

journal = "Microporous and Mesoporous Materials",

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TY - JOUR

T1 - Immobilization and exchange of perrhenate in sodalite and cancrinite

AU - Dickson, Johnbull O.

AU - Harsh, James B.

AU - Flury, Markus

AU - Pierce, Eric M.

PY - 2015/5/28

Y1 - 2015/5/28

N2 - 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. 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-. 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.

AB - 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. 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-. 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.

KW - Anion selectivity

KW - Feldspathoids

KW - Ion exchange

KW - Perrhenate

KW - Technetium-99

UR - https://www.scopus.com/pages/publications/84930199190

U2 - 10.1016/j.micromeso.2015.05.011

DO - 10.1016/j.micromeso.2015.05.011

M3 - Article

AN - SCOPUS:84930199190

SN - 1387-1811

VL - 214

SP - 115

EP - 120

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

ER -

Immobilization and exchange of perrhenate in sodalite and cancrinite

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