Size dispersion and colloid mediated radionuclide transport in a synthetic porous media

Delos, A.; Walther, Clemens; Schäfer, Thorsten; Büchner, Sebastian

doi:10.1016/j.jcis.2008.05.017

Cited by 24 publications

(16 citation statements)

References 34 publications

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“…This is undertaken by the ablation of disruptive fraction on surface of clay particles into aquifer solutions, producing the observed suspension colloids. With suspension colloids, migration of these radionuclides, which adsorbed tightly on suspension colloids, becomes unpredictable, depending upon the hydrological environments of groundwater flow [11,12]. That is, the migration of radionuclides would be far beyond the expected distance when considering only the adsorption between radionuclides and clay minerals.…”

Section: Introductionmentioning

confidence: 99%

Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository

Wang

Liu

et al. 2010

Journal of Hazardous Materials

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Section: Introductionmentioning

confidence: 99%

Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository

Wang

Liu

et al. 2010

Journal of Hazardous Materials

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“…The previously reported transport velocities of the colloid-associated Pu, Am, and Np were ~1–5% faster than tritium1415161718, as determined by only two single data in breakthrough curves. This rough estimate possibly caused lower velocities than the U Pu / U T (1.14–1.52, depending on the experimental conditions in Table 1) determined by the newly developed model in this study.…”

Section: Discussionmentioning

confidence: 62%

Insights into transport velocity of colloid-associated plutonium relative to tritium in porous media

Xie

Lin

et al. 2014

Sci Rep

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Although faster transport velocities of colloid-associated actinides, bacteria, and virus than nonreactive solutes have been observed in laboratory and field experiments, some questions still need to be answered. To accurately determine the relative velocity (UPu/UT) of 239Pu and tritium representative of the bulk water, a conceptual model of electrostatic interactions coupled with the parabolic water velocity profile in pore channels is developed. Based on the expression for UPu/UT derived from this model, we study the effects of water flow rates and ionic strengths on the UPu/UT. Also, the velocity relationship between Pu, tritium and Sr2+ is explored. The results show that UPu/UT increased fairly linearly with decreasing water flow rates; UPu/UT declined approximately exponentially with increasing Na+ concentrations; the charge properties of colloid-associated Pu (negative), tritium (neutral) and Sr2+ (positive) had a close association with their transport velocities as UPu : UT : USr2+ = 1.41 : 1 : 0.579.

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“…Each pass through the columns resulted in nearly identical transport without evidence for aggregation, straining, or preferential attachment of colloids or changes in the adsorption/desorption behavior of the Am. Colloid breakthrough occurred slightly ahead of the conservative tritium tracer which is evidence for size-exclusion or a size chromatography effect (Delos et al, 2008;Sch€ afer et al, 2004), which prevented the colloids from diffusing into or advecting through the smallest pores. After switching to Am-free SZW, colloid concentrations rapidly decreased to nearly background with almost no tailing, indicating that most of deposited colloids were irreversibly-attached in the column, likely due to straining in narrow pore throats.…”

Section: Discussionmentioning

confidence: 99%

Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

Dittrich

Boukhalfa

Ware

et al. 2015

Journal of Environmental Radioactivity

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Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater-bentonite-fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L(-1)) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10(-10) M (241)Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (k(f)) of 0.01-0.02 h(-1). Am recoveries in each column were 55-60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h(-1) in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. Our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long distance scales because of the ability of the fracture materials to rapidly strip Am from the bentonite colloids and the apparent lack of a strong binding site that would keep a fraction of the Am strongly-associated with the colloids.

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Size dispersion and colloid mediated radionuclide transport in a synthetic porous media

Cited by 24 publications

References 34 publications

Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository

Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository

Insights into transport velocity of colloid-associated plutonium relative to tritium in porous media

Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

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