Colloidal aggregation and transport behavior of asbestos particles in porous media

Asbestos particles can form aggregates in the aqueous phase within the saturated/partially saturated porous media (geomaterials in contaminated environments, in vivo, etc.). Recent studies by Mohanty et al. showed that the organic acids lead to a breakthrough of asbestos particles in saturated natural soils, while other variations of geochemical conditions (pH, etc.) do not appear to influence their mobility. However, the mechanism behind this observation is not yet well-understood and a fundamental understanding of the interaction mechanisms between asbestos particles and the porous medium is required. According to extensive research by Wu et al., the asbestos particles exhibit anisotropic diffusion behavior, while the particle aspect ratio is an important factor for the morphology, growth and size distribution of the aggregation.

This research aims at investigating the aggregation and mobility of asbestos particles through porous media by visualizing and analyzing the governing physical mechanisms at the particle scale. The colloidal aggregation of asbestos particles in porous media is investigated in the current study.

Due to the complexity of the pore structure of natural geomaterials, an optically transparent porous medium is selected. The candidate model medium is the granules of the amorphous fluoropolymer Nafion with a similar reflective index to that of water and a high optical transmission. Nafion features high resistance to pH, which enables us to analyze the aggregation and transport behavior of asbestos particles under different geochemical conditions. A flow cell is designed for the flow analysis of the asbestos suspension through the porous medium. The setup provides observation of the asbestos aggregations and their transport through the porous structure, while the reconstruction of the porous medium can be carried out in the next separate phase [might want to have a sentence that says ”there are going to be multiple research phases, (i) (ii) (iii)”]. This feature enables to observe the mobility of particles and their interaction with porous medium independently.

EXPECTED RESULTS AND POSSIBLE IMPLICATIONS

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