Iodosodalite synthesis with hot isostatic pressing of precursors produced from aqueous and hydrothermal processes

Chong, Saehwa; Riley, Brian J.; Asmussen, R. Matthew; Lawter, Amanda R.; Bruffey, Stephanie H.; Nam, Junghune; McCloy, John S.; Crum, Jarrod V.

doi:10.1016/j.jnucmat.2020.152222

Cited by 20 publications

(17 citation statements)

References 48 publications

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“…Ag-exchanged zeolites are suitable for consolidation by hot isostatic pressing (HIP), being chemically converted to a silver iodide sodalite (Ag 4 Al 3 Si 3 O 12 I). However, the wasteform is unstable under reducing groundwater conditions and iodine-loading is performed in idealised conditions, rather than an industrially-realistic capture process [81,82]. Ag-functionalised silica aerogels are suitable for sintering by HIP, as well as hot uniaxial pressing (HUP) and spark plasma sintering (SPS), after removal of organic moieties by heating [83].…”

Section: Wasteform Considerationsmentioning

confidence: 99%

Capture of aqueous radioiodine species by metallated adsorbents from wastestreams of the nuclear power industry: a review

et al. 2021

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Iodine-129 poses a significant challenge in the drive towards lowering radionuclide emissions from used nuclear fuel recycling operations. Various techniques are employed for capture of gaseous iodine species, but it is also present, mainly as iodide anions, in problematic residual aqueous wastestreams, which have stimulated research interest in technologies for adsorption and retention of the radioiodine. This removal effort requires specialised adsorbents, which use soft metals to create selectivity in the challenging chemical conditions. A review of the literature, at laboratory scale, reveals a number of organic, inorganic and hybrid adsorbent matrices have been investigated for this purpose. They are functionalised principally by Ag metal, but also Bi, Cu and Pb, using numerous synthetic strategies. The iodide capacity of the adsorbents varies from 13 to 430 mg g−1, with ion-exchange resins and titanates displaying the highest maximum uptakes. Kinetics of adsorption are often slow, requiring several days to reach equilibrium, although some ligated metal ion and metal nanoparticle systems can equilibrate in < 1 h. Ag-loaded materials generally exhibit superior selectivity for iodide verses other common anions, but more consideration is required of how these materials would function successfully in industrial operation; specifically their performance in dynamic column experiments and stability of the bound radioiodine in the conversion to final wasteform and subsequent geological storage. Article highlights Metallated adsorbents for the capture and retention of radioiodine in the nuclear industry are assessed. The strengths and weaknesses of organic, inorganic and hybrid support matrices and loading mechanisms are discussed. Pathways for progression of this technology are proposed. Graphic abstract

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Section: Wasteform Considerationsmentioning

confidence: 99%

Capture of aqueous radioiodine species by metallated adsorbents from wastestreams of the nuclear power industry: a review

et al. 2021

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“…One particular isotope ( 129 I) requires a special attention because of 1) its long half-life (>15 Ma) and 2) its high mobility and volatility in environment [3,6,7]. Currently, several academic studies aim at developing durable conditioning matrices for this radioisotope but no ideal industrial solution has emerged for immobilizing it in a permanent and safe manner [8][9][10][11][12][13][14][15][16][17]. Although alternative surrogates have been recently suggested with phosphate glasses [18,19], the immobilization of radioactive elements is often achieved in aluminoborosilicate glasses synthesized at ambient pressure, high-temperature and representing a good compromise that 1) will contain high concentration in radioactive elements to reduce the disposal space; 2) will be stable through time; 3) will not be damaged by radiation and heating; 4) will present high chemical durability [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Predicting iodine solubility at high pressure in borosilicate nuclear waste glasses using optical basicity: an experimental study

et al. 2022

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Constraining the systematic evolution of iodine solubility in borosilicate glasses is required for the formulation of adequate glass matrices able to immobilize 129 I representing a major troublesome radioisotopes produced by nuclear anthropic activities.We investigated experimentally the change in iodine solubility in a large series of borosilicate glasses synthesized under high-pressure conditions (1.5 GPa) and at 1350°C. The nature of network modifying cation (Na, K, Rb, Ca, Ba and Sr) and the concentration of B2O3 (~<10 mol.% and ~>10 mol.%) have been tested. The XPS measurements showed that iodine speciation in glasses is mostly represented by iodide (I -) for a range of iodine solubility from 0.3 to 3.1 mol.% as determined by SEM EDS and LA-ICP-MS analyses.The iodine solubility is enhanced in glasses with lower B2O3 content and with a higher concentration in network modifying cation. Regardless of the cation nature: alkali or alkalineearth; increasing the cation size appears to induce a decrease in iodine solubility. We used the optical basicity (ΛGlass) and iono-covalent parameter (ICPGlass) to express the large variety of investigated glass compositions; both relating to the electron donor capability of the glass. We show that iodine solubility is positively correlated to ΛGlass and accordingly negatively correlated to ICPGlass. It implies that more iodine will be dissolved in glass compositions having a stronger electron donating capability. Evidence of the relationship between iodine solubility and oxygen network is shown by the iodine solubility positive trend with equilibrium constant of the oxygen speciation. Future work should take these parameters into consideration for modeling iodine solubility in borosilicate glasses providing additional information are collected such as the boron, aluminum and silicon speciation in glasses.

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“…If a tether is required to install the getter metal, this can add extra steps and costs. Some thought has also been given to the recovery of the Ag following iodine capture such as the reaction of AgI with Na 2 S to form Ag 2 S and NaI, as shown in eq , the latter of which could be incorporated into a different waste form such as iodosodalite [i.e., Na 8 (AlSiO 4 ) 6 I 2 ] , or iodoapatite [e.g., Pb 10 (VO 4 ) 6 I 2 ] starting from NaI. However, several other getter metals are available that could be less expensive such as Cu and Bi, albeit with different capture performances than Ag. , …”

Section: Introductionmentioning

confidence: 99%

Silver-Loaded Xerogel Nanostructures for Iodine Capture: A Comparison of Thiolated versus Unthiolated Sorbents

Riley

Chong

Marcial

et al. 2022

ACS Appl. Nano Mater.

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This paper describes the development and provides comparisons of thiolated (−SH) and unthiolated Ag–Al–Si–O xerogels for iodine gas capture. These xerogels were produced from alkoxides and then heat-treated at 350 °C to provide mechanical strength for subsequent processing steps. Then, a portion of the xerogels was thiolated using (3-mercaptopropyl)trimethoxysilane. Next, thiolated and unthiolated batches were ion-exchanged in AgNO3 solutions where Ag+ replaced Na+ in the gel network on a near 1:1 molar basis. Subsamples of the Ag-exchanged xerogels were subjected to a reduction step in H2/Ar to convert Ag+ to Ag0 where the rest of the Ag-exchanged (Ag+) were not reduced. X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy revealed nanoscale Ag0 in the Ag+ samples despite no active reduction where actively reduced samples had bimodal Ag0 distribution of ∼2–3 nm hexagonal and ∼6–7 nm cubic crystallites. Synchrotron X-ray absorption spectroscopy was used to assess the oxidization states of Ag, S, and I within the different xerogel samples. The specific surface areas of the base xerogels decreased as subsequent treatments were performed on the as-made samples, albeit the decreases were smaller than aerogel equivalents of these samples from a previous study. All iodine-loaded Ag-based samples showed a mixture of β-AgI and γ-AgI. Comparisons of iodine-loading results with other Ag-based iodine sorbents show that the thiolated Ag0-xerogels in this work have one of the highest iodine-loading capacities (q e) reported to date in saturated conditions with the thiolated Ag0-xerogel showing 522 mg iodine per g of the sorbent.

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Iodosodalite synthesis with hot isostatic pressing of precursors produced from aqueous and hydrothermal processes

Cited by 20 publications

References 48 publications

Capture of aqueous radioiodine species by metallated adsorbents from wastestreams of the nuclear power industry: a review

Capture of aqueous radioiodine species by metallated adsorbents from wastestreams of the nuclear power industry: a review

Predicting iodine solubility at high pressure in borosilicate nuclear waste glasses using optical basicity: an experimental study

Silver-Loaded Xerogel Nanostructures for Iodine Capture: A Comparison of Thiolated versus Unthiolated Sorbents

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