Geological Disposal of Nuclear Waste: Fate and Transport of Radioactive Materials

Sharma, Prabhakar

doi:10.5772/50391

Cited by 4 publications

(3 citation statements)

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“…The clogging of porous media by colloids is a complex process that depends on many physical and chemical properties of the colloid and fluid(s) and the pore space geometry. ,− Our experimental observations and analysis demonstrate that colloid clogging occurs only in liquid filaments for the small-grain packings at low levels of wetting phase saturation resulting from a high flow rate. Note that this behavior should be distinguished from hydrodynamic bridging, which generally refers to the process in which multiple colloids, with individual sizes much smaller than the size of the pore constriction, simultaneously arrive and block the pore constriction by forming a stable bridge or arch. ,, Therefore, bridging often occurs near the contact point of two solid grains and is related to colloid concentration and size . However, the liquid filaments connecting two pendular rings are located on the grain surface, as shown in Figure e, and thus, the colloid transport in liquid filaments is not confined by the pore constriction but by the geometry of the wetting fluid structure.…”

Section: Resultsmentioning

confidence: 99%

“…Note that this behavior should be distinguished from hydrodynamic bridging, which generally refers to the process in which multiple colloids, with individual sizes much smaller than the size of the pore constriction, simultaneously arrive and block the pore constriction by forming a stable bridge or arch. 41,42,58 Therefore, bridging often occurs near the contact point of two solid grains and is related to colloid concentration and size. 42 However, the liquid filaments connecting two pendular rings are located on the grain surface, as shown in Figure 3e, and thus, the colloid transport in liquid filaments is not confined by the pore constriction but by the geometry of the wetting fluid structure.…”

Section: ■ Experimental Methods and Materialsmentioning

confidence: 99%

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Three-Dimensional Visualization Reveals Pore-Scale Mechanisms of Colloid Transport and Retention in Two-Phase Flow

Yang

et al. 2023

Environ. Sci. Technol.

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Colloids are ubiquitous in the natural environment, playing an important role in facilitating the transport of absorbed contaminants. However, due to the complexities arising from twophase flow and difficulties in three-dimensional observations, the detailed mechanisms of colloid transport and retention under twophase flow are still not well understood. In this work, we visualize the colloid transport and retention during immiscible two-phase flow based on confocal microscopy. We find that the colloid transport and retention behaviors depend strongly on the flow rate and pore/grain size. At low levels of saturation (high flow rate) with the wetting liquid mainly present as pendular rings, the colloids can aggregate at the liquid filaments in small-grain packings and are uniformly distributed in large-grain packings. Through theoretical analysis of the pendular ring geometry, we elucidate the mechanism responsible for the strong dependence of colloid clogging behavior on solid grain size. Our results further demonstrate that even at dilute concentrations, colloids can alter the flow paths and the wetting fluid topology, suggesting a strong two-way coupling dynamics between immiscible two-phase flow and colloid transport and calling for improved predictive models to incorporate the overlooked clogging behavior.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Methods and Materialsmentioning

confidence: 99%

Three-Dimensional Visualization Reveals Pore-Scale Mechanisms of Colloid Transport and Retention in Two-Phase Flow

Yang

et al. 2023

Environ. Sci. Technol.

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“…The total collector efficiency (0) is assumed to be the sum of three distinct collision mechanisms, collision due to particle interception (I), gravity sedimentation (G), and diffusion (D) (Sharma et al, 2008a;Liu et al, 2009;Sharma 2012). In order to estimate the unknown parameters, the model was programmed to find the best set of parameters which produce the simulated breakthrough curve with minimum root-mean-square error (RMSE) from the observed breakthrough curve using an optimization routine.…”

Section: Mathematical Modelmentioning

confidence: 99%

Transport and retention of carbon-based engineered and natural nanoparticles through saturated porous media

et al. 2016

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Transport and retention of carbon-based engineered and natural nanoparticles through saturated porous media. Journal of nanoparticle research, (70)http://dx.doi.org/10.1007/s11051-016- Access to the published version may require subscription. N.B. When citing this work, cite the original published paper. Accepterad versionPermanent link to this version: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-292975 2 Abstract 1 Carbon-based engineered nanoparticles have been widely used due to their small size and 2 unique physical and chemical properties. At the same time, the toxic effect of these 3 nanoparticles on human and fish cells has also been observed; therefore, their release and 4 distribution into the surface and subsurface environment is a subject of concern. The aim of 5 this research is to evaluate and compare transport and retention of two types of engineered 6 nanoparticles (multi-walled carbon nanotubes (MWCNT) and C60) and natural carbon 7 nanoparticles collected from a fire accident. Several laboratory experiments were conducted 8 to observe transport behavior of nanoparticles through a column packed with silica sand. The 9 column experiments were intended to monitor the effect of ionic strength on transport of 10 nanoparticles as a function of their shapes. It was observed that the mobility of both types of 11 engineered nanoparticles was reduced with increase in ionic strength from 1.34 mM to 60 12 mM. However, at ionic strength upto 10.89 mM, spherical nanoparticles were more mobile 13 than cylindrical nanoparticles but the mobility of cylindrical nanoparticles became 14 significantly higher than spherical nanoparticles at 60 mM. In comparison with natural fire 15 nanoparticles, both types of engineered nanoparticles were much less mobile at the selected 16 experimental condition in this study. Furthermore, inverse modeling was used to calculate 17 parameters such as attachment efficiency, the longitudinal dispersivity, and capacity of the (Petersen et al., 2011). Although allotropes of carbon, fullerene (C60) and CNTs 40 are hydrophobic in nature, the dispersion of multi-walled carbon nanotubes (MWNTs) and 41 C60 into water in the presence of natural organic matter (NOM) has been reported recently 42 (Hyung et al., 2007; Mashayekhi et al., 2012; Zhang et al., 2014). Natural carbon-based 43 nanoparticles can also be formed during the incomplete burning of coal, oil and gas, garbage 44 or other organic substances (Nisbet and LaGoy, 1992). Migration of these particles, which 45 typically contain large amounts of metals and poly-aromatic hydrocarbons (PAH), is a 46 subject of concern (Hertzberg and Blomqvist, 2003; Sharma et al., 2016). 52However, the effect of shape of carbon based nanoparticles on their transport and retention is 53 still scarcely reported (Seymour et al., 2013). Porous media 104The silica sand was purchased from Sibelco Nordic, Baskarp, Sweden to be used as porous flushed with background solution which was buffered to pH 7 with sodium phosphate buffer. 119The properties ...

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Apparent Permeability Evolution Due to Colloid Migration Under Cyclic Confining Pressure: On the Example of Porous Limestone

et al. 2023

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Geological Disposal of Nuclear Waste: Fate and Transport of Radioactive Materials

Cited by 4 publications

References 92 publications

Three-Dimensional Visualization Reveals Pore-Scale Mechanisms of Colloid Transport and Retention in Two-Phase Flow

Three-Dimensional Visualization Reveals Pore-Scale Mechanisms of Colloid Transport and Retention in Two-Phase Flow

Transport and retention of carbon-based engineered and natural nanoparticles through saturated porous media

Apparent Permeability Evolution Due to Colloid Migration Under Cyclic Confining Pressure: On the Example of Porous Limestone

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