Wettability of clay aggregates-A coarse-grained molecular dynamic study

X Kang and HM Sun and W Yang and RP Chen, APPLIED SURFACE SCIENCE, 532, 147423 (2020).

DOI: 10.1016/j.apsusc.2020.147423

Clay minerals play a vital role in environmental pollution remediation due to their special wettability performance. However, limited by experimental technology and computational costs, wettability mechanism of clay aggregates at mesoscale remains unclear. In this work, the coarse-grained molecular dynamic simulation method has been used as a novel strategy to discover the mesoscale wettability of clay aggregates with water. Through visualization analysis, we have observed that the water droplet firstly got in touch with the clay surface, then some water molecules flowed into clay pores while some adsorbed onto clay platelets edge. With further invasion of water, clay platelets rearranged and reoriented to fit themselves. The clay-water system reached equilibrium under three mechanisms, including normal blocking, non-normal diffusion and interlayer adsorption. The final inhomogeneous equilibrium water droplet had an average contact angle value of 81.5 degrees, which is in good agreement with preceding experimental measurement. These findings help for a better understanding on the wetting property of clay mineral surface and fill a gap of the wettability study on mesoscale level.

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