Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock

Demnitz, Maximilian; Molodtsov, Konrad; Schymura, Stefan; Schierz, Ariette; Müller, K.; Jankovský, Filip; Havlová, Václava; Stumpf, Thorsten; Schmidt, Moritz

doi:10.1016/j.jhazmat.2021.127006

Cited by 8 publications

(13 citation statements)

References 60 publications

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“…Cm(III) sorption on the rock's constituting minerals -primarily feldspar, mica and quartz -was analyzed quantitatively and qualitatively. We observed that Cm(III) sorption uptake and speciation depends not only on the mineral phase but also the surface roughness (Demnitz et al, 2021). An increasing surface roughness leads to higher sorption uptake and a stronger coordination of the sorbed Cm(III).…”

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confidence: 85%

“…In the case that one mineral phase dominates the sorption process, sorption of Cm(III) on other mineral phases will only occur at strong binding sites, typically where surface roughness is high. Areas of feldspar and quartz with high surface roughness additionally showed the formation of sorption species with particularly high sorption strength that could either be interpreted as Cm(III) incorporation species or ternary complexes on the mineral surface (Demnitz et al, 2021).We conclude that in addition to mineral composition, surface roughness needs to be adequately considered to describe interfacial speciation of contaminants and respective retention patterns for the safety assessments of nuclear waste repositories.Kurzfassung. Viele Länder werden geologische Tiefenlager für die Entsorgung ihrer hochradioaktiven Abfälle nutzen.…”

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confidence: 93%

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confidence: 99%

“…Die Cm(III)-Sorption an den Mineralien, aus denen das Gestein besteht -in erster Linie Feldspat, Glimmer und Quarz -, wurde quantitativ und qualitativ analysiert. Die Autoren stellten fest, dass die Aufnahme durch Sorption und Speziation von Cm(III) durch Sorption nicht nur von der Mineralphase, sondern auch von der Oberflächenrauheit abhängig ist (Demnitz et al, 2021). Eine zunehmende Oberflächenrauheit führt zu einer höheren Sorptionsmenge und einer stärkeren Koordination des sorbierten Cm(III).…”

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“…In dem Fall, dass eine Mineralphase den Sorptionsprozess dominiert, erfolgt die Sorption von Cm(III) an andere Mineralphasen nur an starken Bindungsstellen, typischerweise dort, wo die Oberflächenrauheit hoch ist. Bereiche mit Feldspat und Quarz mit hoher Oberflächenrauheit zeigten darüber hinaus eine Bildung von Sorptionsspezies mit besonders hoher Sorptionsstärke auf, die entweder als Cm(III)-Inkorporationsspezies oder als ternäre Komplexe an der Mineraloberfläche interpretiert werden könnten (Demnitz et al, 2021).…”

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Spatially resolved sorption of Cm(III) on crystalline rock: influence of surface roughness and mineralogy

Demnitz

Molodtsov

Schymura

et al. 2021

Saf. Nucl. Waste Disposal

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Abstract. Many countries will use deep geological repositories to dispose of highly active nuclear waste. Crystalline rock is a potential host rock because of its strong geotechnical stability, low permeability and low solubility; however, its inherent mineralogy is heterogeneous, consisting of a wide set of minerals in varying amounts. Therefore, there is a need for using sophisticated techniques that allow spatial resolution to characterize the nanostructure of such crystalline rock surfaces and the speciation of the actinides therein. As a representative for trivalent actinides, such as Am(III), Np(III), and Pu(III), which are expected to be present due to the reducing conditions encountered in a deep geological repository, we have chosen the actinide Cm(III). Cm(III) possesses excellent luminescence properties, which allows us to not only examine the sorption uptake but also the speciation of Cm(III) on the surface. We combined spatially resolved investigation techniques, such as vertical scanning interferometry, calibrated autoradiography, and Raman microscopy coupled to micro-focus time-resolved laser-induced luminescence spectroscopy (µTRLFS) (Molodtsov et al., 2019). Thus, we were able to correlate mineralogy, surface roughness, and grain boundary effects with radionuclide speciation, allowing us to identify important radionuclide retention processes and parameters (see Fig. 1). Investigations focused on granite from Eibenstock (Germany) and migmatised gneiss from Bukov (Czech Republic). Cm(III) sorption on the rock's constituting minerals – primarily feldspar, mica and quartz – was analyzed quantitatively and qualitatively. We observed that Cm(III) sorption uptake and speciation depends not only on the mineral phase but also the surface roughness (Demnitz et al., 2021). An increasing surface roughness leads to higher sorption uptake and a stronger coordination of the sorbed Cm(III). On the same mineral grains sorption differed significantly depending if an area exhibits a low or high surface roughness. In the case that one mineral phase dominates the sorption process, sorption of Cm(III) on other mineral phases will only occur at strong binding sites, typically where surface roughness is high. Areas of feldspar and quartz with high surface roughness additionally showed the formation of sorption species with particularly high sorption strength that could either be interpreted as Cm(III) incorporation species or ternary complexes on the mineral surface (Demnitz et al., 2021). We conclude that in addition to mineral composition, surface roughness needs to be adequately considered to describe interfacial speciation of contaminants and respective retention patterns for the safety assessments of nuclear waste repositories.

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confidence: 93%

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confidence: 99%

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Spatially resolved sorption of Cm(III) on crystalline rock: influence of surface roughness and mineralogy

Demnitz

Molodtsov

Schymura

et al. 2021

Saf. Nucl. Waste Disposal

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Variability of Radionuclide Sorption Efficiency on Muscovite Cleavage Planes

Schabernack,

Oliveira,

Heine

et al. 2023

Advcd Theory and Sims

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In deep geological repositories for nuclear waste, the surrounding rock formation serves as an important barrier against radionuclide migration. Multiple potential host rocks contain phyllosilicates, which have shown high efficiency in radionuclide sorption. Recent experimental studies report a heterogeneous distribution of adsorbed radionuclides on nanotopographic mineral surfaces. In this study, the energetic differences of surface sorption sites available at nanotopographic structures such as steps, pits, and terraces are investigated. Eleven important surface sites are selected and the energies of ad‐ and desorption reactions are obtained from density functional theory calculations. The adsorption energies are then used for the parameterization of a kinetic Monte Carlo model simulating the distribution of adsorbed europium on a typical nanotopographic muscovite surface. On muscovite, silicon step sites are favorable for europium sorption and lead to an increased adsorption in regions with high step concentrations. Under identical chemical conditions, sorption on typical nanotopographic surfaces is increased by a factor of three compared to atomically flat surfaces. Desorption occurs preferentially at terrace sites, leading to an overall 2.5 times increased retention at nanotopographic structures. This study provides a mechanistic explanation for heterogeneous sorption on nanotopographic mineral surfaces due to the availability of energetically favorable sorption sites.

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Natural and synthetic plagioclases: Surface charge characterization and sorption of trivalent lanthanides (Eu) and actinides (Am, Cm)

Lessing,

Neumann,

Lützenkirchen

et al. 2024

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock

Cited by 8 publications

References 60 publications

Spatially resolved sorption of Cm(III) on crystalline rock: influence of surface roughness and mineralogy

Spatially resolved sorption of Cm(III) on crystalline rock: influence of surface roughness and mineralogy

Variability of Radionuclide Sorption Efficiency on Muscovite Cleavage Planes

Natural and synthetic plagioclases: Surface charge characterization and sorption of trivalent lanthanides (Eu) and actinides (Am, Cm)

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