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Asphaltenes generally aggregate, then precipitate and deposit on the surfaces of environmental media (soil, sediment, aquifer, and aquitard). Previous studies have recognized the importance of asphaltene aggregates on the wettability of aquifer systems, which has long been regarded as a limiting factor that determines the feasibility and remediation efficiency of sites contaminated by heavy oils. However, the mechanisms/factors associated with precipitant effects on asphaltene aggregates structure, and how the precipitant effects influence the wettability of surfaces remain largely unknown. Here, we observe the particle-by-particle growth of asphaltene aggregates formed at different precipitant concentrations. Our results show that aggregates for all precipitant concentrations are highly polydisperse with self-similar structures. A higher precipitant concentration leads to a more compacted aggregates structure, while precipitant concentration near to onset point results in a less compact structure. The well-known Smoluchowski model is inadequate to describe the structural evolutions of asphaltene aggregates, even for aggregation scenarios induced by a precipitant concentration at the onset point where the Smoluchowski model is expected to explain the aggregate size distribution. It is suggested that aggregates with relative high fractal dimensions observed at high precipitant concentrations can be used to explain the relatively low Stokes settling velocities observed for large asphaltene aggregates. In addition, asphaltene aggregates with high fractal dimensions are likely to have high density of nanoscale roughness which could enhance the hydrophobicity of interfaces when they deposit on the sand surface. Findings obtained from this study advance our current understandings on the fate and transport of heavy oil contaminants in the subsurface environment, which will have important implications for designing and implementing more effective and efficient remediation technologies for contaminated sites.
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Introduction of Heterogeneous Cell Properties for Modeling Emergent Stress Fields in Multicellular Systems
We present the first experimental evidence that supports that low stresses are experienced by central cells and is driving the biological response of aggregates. Our model improves upon previous models, however, it can still become more robust. We plan to obtain higher resolution biophysical data with validation to further alter cell contractility distributions and iterate our model’s parameters. It is necessary to incorporate heterogeneous mechanical properties to accurately estimate the distribution of the emergent stress fields in our aggregates.
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- Award ID(s):
- 1761432
- PAR ID:
- 10095628
- Date Published:
- Journal Name:
- Summer Biomechanics, Biotransport, and Bioengineering Meeting
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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