Iodine Immobilization by Sodalite Waste Form

Nakazawa, T.; Kato, Hirohisa; Okada, Kazuki; Ueta, Shinzo; Mihara, Midori

doi:10.1557/proc-663-51

Cited by 24 publications

(9 citation statements)

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“…Typical solid-state synthesis requires around 800°C, 2 but the volatility of iodine occurs at similar temperature resulting in substantial loss of iodine. 2,20 Also, longer synthesis times at 850°C showed the transformation of sodalite to nepheline in the case of chlorosodalite. 21 The formation of aluminosilicate frameworks under hydrothermal conditions involves gelation, dissolution, nucleation, and crystallization as shown in Figure 2.…”

Section: Iodosodalitementioning

confidence: 99%

“…Iodosodalite is typically synthesized by high‐temperature solid‐state routes or lower temperature aqueous routes, such as hydrothermal or wet chemistry methods. Typical solid‐state synthesis requires around 800°C, but the volatility of iodine occurs at similar temperature resulting in substantial loss of iodine . Also, longer synthesis times at 850°C showed the transformation of sodalite to nepheline in the case of chlorosodalite…”

Section: Introductionmentioning

confidence: 99%

“…Sodalite is a microporous material with a cage‐like structure that can incorporate various ions, and it has been studied for many industrial applications including nuclear waste forms, optical data storage, and semiconductor quantum dots . Sodalite has a generic chemical formula of M 8 Al 6 Si 6 O 24 X 2 often written as M 8 (AlSiO 4 ) 6 X 2 , where M represents a cation (eg, Na + , Ag + , Ca + , Li + ) and X represents an anion (eg, Cl − , I − , OH − , IO 3 − ).…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of iodosodalite

et al. 2017

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The effects of six process variables were investigated on the hydrothermal growth of iodosodalite, Na8Al6Si6O24I2: pH (NaOH concentration), aging time, temperature, Al/Si ratio, precursors used (i.e., zeolite 4A, kaolinite, meta‐kaolin, colloidal silica, and sodium aluminate), and precursor concentration. Powder X‐ray diffraction (XRD) with Rietveld refinements, X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were performed to characterize the structures, phase fractions, chemical state, and surface morphology of the synthesized products. Iodosodalite yield increased as aging time and pH increased. The crystallization of iodosodalite was favored in the temperature range 140°C‐180°C. Decreasing the Al/Si ratio by half increased the crystallization of basic cancrinite. Lowering the precursor concentration by adding water revealed the crystallization of nepheline hydrate I and a decrease in the sodalite fraction. Among the tested precursors, zeolite 4A yielded the highest mass fraction of iodosodalite in the synthesized powders. From the aging time and temperature variation experiments, the phase transformation of zeolite A→sodalite→cancrinite was observed. XPS and FTIR results showed the presence of only iodide but not iodate in the synthesized product. The crystallization of various minerals suggests that mechanisms for transport of the ions and formation of the aluminosilicate frameworks vary with hydrothermal conditions.

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Section: Iodosodalitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of iodosodalite

et al. 2017

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“…Limited leachability data were available in the literature for natural sodalite and iodine sodalite for comparison. Sodalite was studied as a waste form for immobilizing the long lived 129 I isotope by Nakazawa et al ., who measured a normalized release rate of ~10 −4 g·m −2 ·d −1 for the synthesized iodine sodalite and ~10 −5 g·m −2 ·d −1 for the natural sodalite. The duration of the leachability testing was 70 days.…”

Section: Resultsmentioning

confidence: 99%

Solution‐Derived, Chloride‐Containing Minerals as a Waste Form for Alkali Chlorides

et al. 2012

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Sodalite (Na 8 (AlSiO 4 ) 6 Cl 2 ) and cancrinite ((Na,K) 6 Ca 2 (AlSiO 4 ) 6 Cl 4 ) are environmentally stable, chloride-containing minerals that are a logical waste form option for the mixed alkali chloride salt waste stream that is generated from a proposed electrochemical separations process during nuclear fuel reprocessing. Here, we discuss a low-temperature, solution-based process to make these phases where sodalite particles are produced in the form of a fine powder with particle sizes on the order of 1-10 lm. Due to the small particle size, these powders require additional treatment to form a monolith. In this study, the powders were pressed into pellets and fired to achieve >90% of the theoretical density of sodalite (2.27 3 10 À3 kg/m 3 ). The cancrinite structure, identified as the best candidate mineral form in terms of waste loading capacity, was only produced on a limited basis but was converted to sodalite upon firing. Here, we discuss the specifics of the solution-based approach, the chemical durability of select waste forms as well as the steps taken to maximize the chloride-containing phases, decrease chloride loss during pellet firing, and to increase pellet densities.E. Vance-contributing editor Manuscript No. 31209.

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“…Sodalite anion chemistry is flexible due to the relatively large cage structure, and compounds incorporating halides (e.g., bromide and iodide) and oxyanions (e.g., tungstate, molybdate, permanganate, chlorate, perchlorate, nitrate, etc.) have been synthesised [3][4][5][6][7][8][9][10][11]. In particular, incorporation of perrhenate (ReO 4 − ) to the sodalite cage structure has been the focus of several studies due to its similarity to pertechnetate (TcO 4 − ) and applications in nuclear waste management [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Perrhenate sodalite growth from alkali silicate melts by noble metal catalysis

Anenburg

Losq

2019

SN Appl. Sci.

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Perrhenate sodalite (Na 8 Al 6 Si 6 Re 2 O 32) which contains the perrhenate anion (ReO 4 −) has been synthesised in equilibrium with Na-Fe-rich aluminosilicate melt and Re metal at 1100 °C and 500 MPa. Quenched glasses contain a homogeneous distribution of nepheline and magnetite, whereas sodalite only forms a crust on noble metal surfaces (Pt, Pt-Rh, Ag-Pd, and Re) in contact with the glass. The sodalite have been characterised by wavelength-dispersive X-ray spectroscopy and Raman spectroscopy. The experimental products contain both Re(0) and Re(VII), but other oxidation states of Re were not detected, suggesting the role of Na as a higher oxidation state stabiliser. Sodalite has potential uses for immobilising volatile Re and Tc during nuclear waste vitrification. Our study demonstrates the thermodynamic stability of perrhenate sodalite at Na-rich aluminosilicate melts at high temperature and pressure conditions.

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Iodine Immobilization by Sodalite Waste Form

Cited by 24 publications

References 1 publication

Synthesis and characterization of iodosodalite

Synthesis and characterization of iodosodalite

Solution‐Derived, Chloride‐Containing Minerals as a Waste Form for Alkali Chlorides

Perrhenate sodalite growth from alkali silicate melts by noble metal catalysis

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