Mechanism of iodine release from iodoapatite in aqueous solution

Zhang, Zelong; Heath, Aubrey A.; Valsaraj, Kalliat T.; Ebert, W. L.; Yao, Tiankai; Lian, Jie; Wang, J.

doi:10.1039/c7ra11049a

Cited by 23 publications

(42 citation statements)

References 30 publications

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“…Details of the synthesis and characterization of these samples were reported previously in separate publications. 25,29,37 The leaching method was adopted from ASTM C1308 standard test, as described in the previous study 29,37 . Four parallel experiments were conducted simultaneously for 14 days in four different leaching solutions: 0.1 mol/L NaCl, 0.1 mol/L Na2CO3, 0.1 mol/L Na3PO4, and 0.1 mol/L Na2SO4.…”

Section: Methodsmentioning

confidence: 99%

“…44 Interestingly, both CO3 2and PO4 3leached surfaces showed visible OHstretching vibration near 3500 cm -1 , 34,44 which also occurred on water leached surface under IR transmission mode. 29…”

Section: Leached Surface Characterization By Ir Analysismentioning

confidence: 99%

“…Our previous study on iodine release in deionized water suggests that the iodine release is driven by short-term diffusion and long-term dissolution. 29…”

Section: Effect Of Ionic Species On the Dissolution Ratementioning

confidence: 99%

“…In addition, apatite ceramics is a promising material due to its thermal, mechanical, and chemical stability. 13,25,28,29 These advantages are also demonstrated in nature as apatite has been found as a retention matrix for actinides and fission products in natural fission reactors at Franceville basin in Africa. 22,30 Several chemical durability tests have been performed on single-phase crystal waste forms.…”

Section: Introductionmentioning

confidence: 98%

“…37 To address the issues of solution feedback, a semi-dynamic leaching method was implemented by Zhang et al in 2018 to quantify the processes involved in the iodine release of an iodine-bearing apatite. 29 In their experiment, deionized water solutions, as the leachant, were replaced periodically to minimize the solution feedback. They demonstrated that iodine released from apatite is driven by short-term diffusion and long-term matrix dissolution.…”

Section: Introductionmentioning

confidence: 99%

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Effect of solution chemistry on the iodine release from iodoapatite in aqueous environments

Zhang¹,

Gustin²,

Xie³

et al. 2019

Preprint

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To ensure the safe disposal of nuclear waste, understanding the release process of radionuclides retained in the nuclear waste forms is of vital importance. Iodoapatite Pb9.85(VO4)6I1.7, a potential waste form for iodine-129, was selected as a model system for ceramic waste forms in this study to understand the effect of aqueous species on iodine release. Semi-dynamic leaching tests were conducted on bulk samples in cap-sealed Teflon vessels with 0.1 mol/L NaCl, Na2CO3, Na3PO4, and Na2SO4 solutions under 90 °C, fixed sample surface area to solution volume ratio of 5/m, and periodic replacement of leaching solutions. The reacted solutions were then analyzed by Inductively Coupled Plasma-Mass Spectrometry and Inductively Coupled Plasma-Optical Emission Spectrometry; the leached surfaces were characterized by X-ray diﬀraction, scanning electron microscopy, and infrared spectroscopy. The result shows that, compared to deionized water, the ion-rich solutions enhanced the iodine release as a result of the increased ionic strength, reduced activity coefficient of dissolved species, and increased solution pH. Surface reactions can lead to the formations of secondary phases by ion-exchange and precipitation. These findings suggest that an ion-rich environment in the geological repository can be detrimental to the disposal safety of the apatite waste form.

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Section: Methodsmentioning

confidence: 99%

Section: Leached Surface Characterization By Ir Analysismentioning

confidence: 99%

“…Our previous study on iodine release in deionized water suggests that the iodine release is driven by short-term diffusion and long-term dissolution. 29…”

Section: Effect Of Ionic Species On the Dissolution Ratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Effect of solution chemistry on the iodine release from iodoapatite in aqueous environments

Zhang¹,

Gustin²,

Xie³

et al. 2019

Preprint

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Release behavior of iodine during leaching and calcination of phosphate rock

Peng

Xiang

et al. 2021

Environ Sci Pollut Res

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Cs3Bi2I9-hydroxyapatite composite waste forms for cesium and iodine immobilization

et al. 2022

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Perovskite-based ceramic composites were developed as potential waste form materials for immobilizing cesium (Cs) and iodine (I) with high waste loadings and chemical durability. The perovskite Cs3Bi2I9 has high Cs (22 wt%) and I (58 wt%) content, and thus can be used as a potential host phase to immobilize these critical radionuclides. In this work, the perovskite Cs3Bi2I9 phase was synthesized by a cost effective solution-based approach, and was embedded into a highly durable hydroxyapatite matrix by spark plasma sintering to form dense ceramic composite waste forms. The chemical durabilities of the monolithic Cs3Bi2I9 and Cs3Bi2I9—hydroxyapatite composite pellets were investigated by static and semi-dynamic leaching tests, respectively. Cs and I are incongruently released from the matrix for both pure Cs3Bi2I9 and composite structures. The normalized Cs release rate is faster than that of I, which can be explained by the difference in the strengths between Cs-I and Bi-I bonds as well as the formation of insoluble micrometer-sized BiOI precipitates. The activation energies of elemental releases based on dissolution and diffusion-controlled mechanisms are determined with significantly higher energy barriers for dissolution from the composite versus that of the monolithic Cs3Bi2I9. The ceramic-based composite waste forms exhibit excellent chemical durabilities and waste loadings, commensurate with the state-of-the-art glass-bonded perovskite composites for I and Cs immobilization.

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Mechanism of iodine release from iodoapatite in aqueous solution

Abstract: Incongruent release of iodine from iodoapatite (Pb5(VO4)3I) for immobilization of129iodine, controlled by exchange of iodide and hydroxide in solution.

Cited by 23 publications

References 30 publications

Effect of solution chemistry on the iodine release from iodoapatite in aqueous environments

Effect of solution chemistry on the iodine release from iodoapatite in aqueous environments

Release behavior of iodine during leaching and calcination of phosphate rock

Cs3Bi2I9-hydroxyapatite composite waste forms for cesium and iodine immobilization

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