Study of the contaminant transport into granite microfractures using nuclear ion beam techniques

Alonso, Úrsula; Missana, Tiziana; Patelli, Alessandro; Rigato, V.; Rivas, Pedro José

doi:10.1016/s0169-7722(02)00116-x

Cited by 14 publications

(2 citation statements)

References 12 publications

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“…Adsorption of contaminants was observed on humic substances, − bacteria, and mineral colloids . Important examples of mineral colloids in repositories are iron oxides, formed during rock weathering, , or clay minerals such as bentonite from the engineered barrier. − The host rock of geological repositories, for example, granite, provides collector surfaces for the retention of colloids and potentially associated radionuclides . Thus, it is essential to understand quantitatively the sorption reactions at rock surfaces in order to evaluate the long-term safety assessment of geological nuclear waste disposals under advective flow conditions.…”

Section: Introductionmentioning

confidence: 99%

Site-Specific Retention of Colloids at Rough Rock Surfaces

Darbha

Luetzenkirchen

Schäfer

2012

Environ. Sci. Technol.

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The spatial deposition of polystyrene latex colloids (d = 1 μm) at rough mineral and rock surfaces was investigated quantitatively as a function of Eu(III) concentration. Granodiorite samples from Grimsel test site (GTS), Switzerland, were used as collector surfaces for sorption experiments. At a scan area of 300 × 300 μm(2), the surface roughness (rms roughness, Rq) range was 100-2000 nm, including roughness contribution from asperities of several tens of nanometers in height to the sample topography. Although, an increase in both roughness and [Eu(III)] resulted in enhanced colloid deposition on granodiorite surfaces, surface roughness governs colloid deposition mainly at low Eu(III) concentrations (≤5 × 10(-7) M). Highest deposition efficiency on granodiorite has been found at walls of intergranular pores at surface sections with roughness Rq = 500-2000 nm. An about 2 orders of magnitude lower colloid deposition has been observed at granodiorite sections with low surface roughness (Rq < 500 nm), such as large and smooth feldspar or quartz crystal surface sections as well as intragranular pores. The site-specific deposition of colloids at intergranular pores is induced by small scale protrusions (mean height = 0.5 ± 0.3 μm). These protrusions diminish locally the overall DLVO interaction energy at the interface. The protrusions prevent further rolling over the surface by increasing the hydrodynamic drag required for detachment. Moreover, colloid sorption is favored at surface sections with high density of small protrusions (density (D) = 2.6 ± 0.55 μm(-1), asperity diameter (φ) = 0.6 ± 0.2 μm, height (h) = 0.4 ± 0.1 μm) in contrast to surface sections with larger asperities and lower asperity density (D = 1.2 ± 0.6 μm(-1), φ = 1.4 ± 0.4 μm, h = 0.6 ± 0.2 μm). The study elucidates the importance to include surface roughness parameters into predictive colloid-borne contaminant migration calculations.

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Section: Introductionmentioning

confidence: 99%

Site-Specific Retention of Colloids at Rough Rock Surfaces

Darbha

Luetzenkirchen

Schäfer

2012

Environ. Sci. Technol.

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“…The result is that radionuclides that are considered as immobile (e.g. Pu, Eu) may be mobile in the presence of bentonite colloids (Alonso et al 2003;Delos et al 2008;Missana et al 2008). Numerous studies have demonstrated that colloid particles can increase the mobility of Am, Np, Pu and U (Kretzschmar & Schäfer 2005).…”

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Study of ⁸⁵ Sr transport through a column filled with crushed granite in the presence of bentonite colloids

Kolomá

Červinka

2016

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The present work is focused on the study of strontium transport through crushed granite in the presence of bentonite colloids under dynamic arrangement. The aim of the experiments was to investigate the effect of bentonite colloids on strontium migration in crushed granite. The tracer behaviour was studied in a column set-up under aerobic conditions with a continuous inlet of the liquid phase of a constant tracer concentration (activity) and flow rate. Defined volumes of liquid phase were sampled at periodic time intervals at the column outlet for the measurements of tracer concentrations (activity). The transport was described by breakthrough curves. The stepwise approach included these steps: (1) an evaluation of the hydrodynamic column properties by the non-sorbing tracer 3 H; (2) a column experiment with bentonite colloids in deionized water was performed; (3) migration of 85 Sr solution in two liquid phases (deionized and synthetic granitic water); and (4) the transport of a radiocolloid suspension in deionized water was studied. Results showed different behaviour of bentonite colloids and strontium in the column. Bentonite colloids behaved as a non-sorbing tracer: conversely, strontium showed strong sorption on granitic material. The strontium transport in the presence of bentonite colloids differed from strontium transport itself. The strontium transport in the presence of colloids was faster than transport without the bentonite colloids. The observed retention of strontium on granite suggests a higher affinity of strontium towards granitic rock than towards bentonite colloids, and showed the reversibility of the sorption of strontium on bentonite colloids.

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Study of the contaminant transport into granite microfractures using nuclear ion beam techniques

Cited by 14 publications

References 12 publications

Site-Specific Retention of Colloids at Rough Rock Surfaces

Site-Specific Retention of Colloids at Rough Rock Surfaces

Study of ⁸⁵ Sr transport through a column filled with crushed granite in the presence of bentonite colloids

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Study of the contaminant transport into granite microfractures using nuclear ion beam techniques

Cited by 14 publications

References 12 publications

Site-Specific Retention of Colloids at Rough Rock Surfaces

Site-Specific Retention of Colloids at Rough Rock Surfaces

Study of 85 Sr transport through a column filled with crushed granite in the presence of bentonite colloids

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Study of ⁸⁵ Sr transport through a column filled with crushed granite in the presence of bentonite colloids