Pressure-induced metathesis reaction to sequester Cs

Junhyuck Im, Donghoon Seoung, Seung Yeop Lee, Douglas A. Blom, Thomas Vogt, Chi Chang Kao, Yongjae Lee

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We report here a pressure-driven metathesis reaction where Ag-exchanged natrolite (Ag16Al16Si24O80 16H2O, Ag-NAT) is pressurized in an aqueous CsI solution, resulting in the exchange of Ag+ by Cs+ in the natrolite framework forming Cs16Al16Si24O80 16H2O (Cs-NAT-I) and, above 0.5 GPa, its high-pressure polymorph (Cs-NAT-II). During the initial cation exchange, the precipitation of AgI occurs. Additional pressure and heat at 2 GPa and 160 °C transforms Cs-NAT-II to a pollucite-related, highly dense, and water-free triclinic phase with nominal composition CsAlSi2O6. At ambient temperature after pressure release, the Cs remains sequestered in a now monoclinic pollucite phase at close to 40 wt % and a favorably low Cs leaching rate under back-exchange conditions. This process thus efficiently combines the pressure-driven separation of Cs and I at ambient temperature with the subsequent sequestration of Cs under moderate pressures and temperatures in its preferred waste form suitable for long-term storage at ambient conditions. The zeolite pollucite CsAlSi2O6 H2O has been identified as a potential host material for nuclear waste remediation of anthropogenic 137Cs due to its chemical and thermal stability, low leaching rate, and the large amount of Cs it can contain. The new water-free pollucite phase we characterize during our process will not display radiolysis of water during longterm storage while maintaining the Cs content and low leaching rate.

Original languageEnglish
Pages (from-to)513-519
Number of pages7
JournalEnvironmental Science and Technology
Volume49
Issue number1
DOIs
Publication statusPublished - 2015 Jan 1

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natrolite
Leaching
leaching
Water
Radioactive Waste
temperature
Zeolites
Radiolysis
zeolite
water
radioactive waste
Chemical stability
Polymorphism
Remediation
ion exchange
remediation
transform
aqueous solution
Temperature
Cations

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Im, J., Seoung, D., Lee, S. Y., Blom, D. A., Vogt, T., Kao, C. C., & Lee, Y. (2015). Pressure-induced metathesis reaction to sequester Cs. Environmental Science and Technology, 49(1), 513-519. https://doi.org/10.1021/es504659z
Im, Junhyuck ; Seoung, Donghoon ; Lee, Seung Yeop ; Blom, Douglas A. ; Vogt, Thomas ; Kao, Chi Chang ; Lee, Yongjae. / Pressure-induced metathesis reaction to sequester Cs. In: Environmental Science and Technology. 2015 ; Vol. 49, No. 1. pp. 513-519.
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Im, J, Seoung, D, Lee, SY, Blom, DA, Vogt, T, Kao, CC & Lee, Y 2015, 'Pressure-induced metathesis reaction to sequester Cs', Environmental Science and Technology, vol. 49, no. 1, pp. 513-519. https://doi.org/10.1021/es504659z

Pressure-induced metathesis reaction to sequester Cs. / Im, Junhyuck; Seoung, Donghoon; Lee, Seung Yeop; Blom, Douglas A.; Vogt, Thomas; Kao, Chi Chang; Lee, Yongjae.

In: Environmental Science and Technology, Vol. 49, No. 1, 01.01.2015, p. 513-519.

Research output: Contribution to journalArticle

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AU - Im, Junhyuck

AU - Seoung, Donghoon

AU - Lee, Seung Yeop

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AU - Kao, Chi Chang

AU - Lee, Yongjae

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N2 - We report here a pressure-driven metathesis reaction where Ag-exchanged natrolite (Ag16Al16Si24O80 16H2O, Ag-NAT) is pressurized in an aqueous CsI solution, resulting in the exchange of Ag+ by Cs+ in the natrolite framework forming Cs16Al16Si24O80 16H2O (Cs-NAT-I) and, above 0.5 GPa, its high-pressure polymorph (Cs-NAT-II). During the initial cation exchange, the precipitation of AgI occurs. Additional pressure and heat at 2 GPa and 160 °C transforms Cs-NAT-II to a pollucite-related, highly dense, and water-free triclinic phase with nominal composition CsAlSi2O6. At ambient temperature after pressure release, the Cs remains sequestered in a now monoclinic pollucite phase at close to 40 wt % and a favorably low Cs leaching rate under back-exchange conditions. This process thus efficiently combines the pressure-driven separation of Cs and I at ambient temperature with the subsequent sequestration of Cs under moderate pressures and temperatures in its preferred waste form suitable for long-term storage at ambient conditions. The zeolite pollucite CsAlSi2O6 H2O has been identified as a potential host material for nuclear waste remediation of anthropogenic 137Cs due to its chemical and thermal stability, low leaching rate, and the large amount of Cs it can contain. The new water-free pollucite phase we characterize during our process will not display radiolysis of water during longterm storage while maintaining the Cs content and low leaching rate.

AB - We report here a pressure-driven metathesis reaction where Ag-exchanged natrolite (Ag16Al16Si24O80 16H2O, Ag-NAT) is pressurized in an aqueous CsI solution, resulting in the exchange of Ag+ by Cs+ in the natrolite framework forming Cs16Al16Si24O80 16H2O (Cs-NAT-I) and, above 0.5 GPa, its high-pressure polymorph (Cs-NAT-II). During the initial cation exchange, the precipitation of AgI occurs. Additional pressure and heat at 2 GPa and 160 °C transforms Cs-NAT-II to a pollucite-related, highly dense, and water-free triclinic phase with nominal composition CsAlSi2O6. At ambient temperature after pressure release, the Cs remains sequestered in a now monoclinic pollucite phase at close to 40 wt % and a favorably low Cs leaching rate under back-exchange conditions. This process thus efficiently combines the pressure-driven separation of Cs and I at ambient temperature with the subsequent sequestration of Cs under moderate pressures and temperatures in its preferred waste form suitable for long-term storage at ambient conditions. The zeolite pollucite CsAlSi2O6 H2O has been identified as a potential host material for nuclear waste remediation of anthropogenic 137Cs due to its chemical and thermal stability, low leaching rate, and the large amount of Cs it can contain. The new water-free pollucite phase we characterize during our process will not display radiolysis of water during longterm storage while maintaining the Cs content and low leaching rate.

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Im J, Seoung D, Lee SY, Blom DA, Vogt T, Kao CC et al. Pressure-induced metathesis reaction to sequester Cs. Environmental Science and Technology. 2015 Jan 1;49(1):513-519. https://doi.org/10.1021/es504659z