Interaction between CO2-rich acidic water, hydrated Portland cement and sedimentary rocks: Column experiments and reactive transport modeling

Dávila, Gabriela; Cama, Jordi; Chaparro, M. Carme; Lothenbach, Barbara; Schmitt, Douglas R.; Soler, Josep M.

doi:10.1016/j.chemgeo.2021.120122

Cited by 5 publications

(3 citation statements)

References 129 publications

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“…Such scenarios include the clean-up and remediation of regions such as the Hanford site, USA, and Fukushima, Japan, where colloid-facilitated radionuclide transport has been confirmed, 99 − 101 the efficient extraction of U from waters, 102 , 103 or in cementitious geological disposal facilities, where hydrotalcite is predicted to form. 104 , 105 …”

Section: Discussionmentioning

confidence: 99%

“…In addition, the improved mechanistic understanding of U(VI) sorption to colloidal hydrotalcite under variable pH and U(VI) concentrations can be used to inform and predict U(VI) behavior across a range of environmental scenarios where LDHs or colloidal particles are present. Such scenarios include the clean-up and remediation of regions such as the Hanford site, USA, and Fukushima, Japan, where colloid-facilitated radionuclide transport has been confirmed, − the efficient extraction of U from waters, , or in cementitious geological disposal facilities, where hydrotalcite is predicted to form. , …”

Section: Discussionmentioning

confidence: 99%

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Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

et al. 2022

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In the United Kingdom, decommissioning of legacy spent fuel storage facilities involves the retrieval of radioactive sludges that have formed as a result of corrosion of Magnox nuclear fuel. Retrieval of sludges may re-suspend a colloidal fraction of the sludge, thereby potentially enhancing the mobility of radionuclides including uranium. The colloidal properties of the layered double hydroxide (LDH) phase hydrotalcite, a key product of Magnox fuel corrosion, and its interactions with U(VI) are of interest. This is because colloidal hydrotalcite is a potential transport vector for U(VI) under the neutral-to-alkaline conditions characteristic of the legacy storage facilities and other nuclear decommissioning scenarios. Here, a multi-technique approach was used to investigate the colloidal stability of hydrotalcite and the U(VI) sorption mechanism(s) across pH 7–11.5 and with variable U(VI) surface loadings (0.01–1 wt %). Overall, hydrotalcite was found to form stable colloidal suspensions between pH 7 and 11.5, with some evidence for Mg 2+ leaching from hydrotalcite colloids at pH ≤ 9. For systems with U present, >98% of U(VI) was removed from the solution in the presence of hydrotalcite, regardless of pH and U loading, although the sorption mode was affected by both pH and U concentrations. Under alkaline conditions, U(VI) surface precipitates formed on the colloidal hydrotalcite nanoparticle surface. Under more circumneutral conditions, Mg 2+ leaching from hydrotalcite and more facile exchange of interlayer carbonate with the surrounding solution led to the formation of uranyl carbonate species (e.g., Mg(UO 2 (CO 3 ) 3 ) 2– (aq) ). Both X-ray absorption spectroscopy (XAS) and luminescence analysis confirmed that these negatively charged species sorbed as both outer- and inner-sphere tertiary complexes on the hydrotalcite surface. These results demonstrate that hydrotalcite can form pseudo-colloids with U(VI) under a wide range of pH conditions and have clear implications for understanding the uranium behavior in environments where hydrotalcite and other LDHs may be present.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

et al. 2022

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“…The initial permeability of the cement is taken from Min et al and is k 0 = 9.4 × 10 −15 m 2 [33]. The reactive surface areas (A 0 ) of the C-S-H, portlandite, and calcite are taken from Davila et al and are 20,000, 300, and 50 m 2 /m 3 mineral [59]. The rates of the reactions are calculated from the reaction network in Table 3, which includes both thermodynamic-controlled aqueous reactions and kineticcontrolled mineral dissolution and precipitation reactions.…”

Section: Numerical Setupmentioning

confidence: 99%

On the Flow of CO2-Saturated Water in a Cement Fracture

Tafen,

Kutchko,

Massoudi

2023

Geosciences

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Cement fractures represent preferential leakage pathways in abandoned wells upon exposure to a CO2-rich fluid. Understanding fracture alteration resulting from geochemical reactions is critical for assessing well integrity in CO2 storage. This paper describes a mathematical model used to investigate the physical and the chemical changes in cement properties when CO2-saturated water is injected into a wellbore. This study examines the flow of a solution of CO2-saturated water in a two-dimensional fractured cement. In this approach, a micro-continuum equation based on the Darcy–Brinkman–Stokes (DBS) equation is used as the momentum balance equation; in addition, reactive transport equations are used to study the coupled processes of reactant transport and geochemical reactions, and the model for cement porosity alteration and fracture enhancement. This paper focuses on the effects of cement porosity, fracture aperture size, and surface roughness. Mineral dissolution and precipitation mechanisms are also considered. Our simulations show that smaller initial fracture apertures tend to a high mineral precipitation self-sealing. However, a complete sealing of the fracture is not observed due to the continuous flow of CO2-saturated water. The calcite precipitation mechanism of a rough fracture (random zigzag shape) differs from that of a smooth/flat fracture surface.

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Application of reactive transport model in understanding the deterioration and failure behavior of cementitious materials: A review

Li,

Wang,

et al. 2024

Construction and Building Materials

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Interaction between CO2-rich acidic water, hydrated Portland cement and sedimentary rocks: Column experiments and reactive transport modeling

Cited by 5 publications

References 129 publications

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

On the Flow of CO2-Saturated Water in a Cement Fracture

Application of reactive transport model in understanding the deterioration and failure behavior of cementitious materials: A review

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