Expansion and Dynamic Stability of Gases between Two Amorphous Silica Particles in Aqueous Solution

The present work reports on the dynamics of gaseous nano-bubbles of CO2, and air (N2 and O2) confined between two deprotonated amorphous silica surfaces. The study uses molecular dynamics simulation. The results show that nano-bubbles of these gases can be stabilsed between two amorphous silica surfaces. The stability is evident from the volumetric data and density analysis. We also propose that the stability of the nano-bubbles is linked to the diffusion of gas molecules in and out of the bubbles. The average values of contact angle of CO2 and air nano-bubbles confined by amorphous silica were found to be on average between 17 and 27 degrees. The volumetric expansion of dense nano-bubbles to equilibrium follows a sigmoid. The data show that this leads to a decrease in gas density in the nano-bubble following a first order exponential decay. The results are in agreement with wettability measurements and experimental studies that investigated the presence of nano-bubbles between amorphous silica surfaces.

By: A. Bojovschi, S. Moore, S. A. Chen, P. Rogers

Published in: RC25492 in 2014

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