Investigating the stability mechanisms of single bulk Nanobubbles: A molecular dynamics perspective

Abstract

In this study, we investigated the relationship between bubble stability and various parameters, including radial pressure, density, surface tension, charge distribution, and Brownian motion, using molecular dynamics simulations and classical bubble stability theory. Our research sheds light on the contrasting behavior of small and large nanobubbles in water, with larger bubbles demonstrating a prolonged lifespan and lower internal pressure. Specifically, nanobubbles with radii of 14 Å, 18 Å, and 22 Å were found to have pressures of 792 atm, 647 atm, and 518 atm, respectively. Notably, our calculations revealed that smaller bubbles possess a thicker liquid-gas interface compared to the larger bubbles. Additionally, our analysis of gas-liquid interactions and mean squared displacement demonstrated that smaller bubble gas molecules experience stronger liquid forces and exhibit enhanced diffusivity. Importantly, we validated the reliability of classical theories by confirming the consistency between the calculated solubility of nanobubbles using Henry's law and simulation results. Moreover, our findings aligned with the predictions of Young's equation regarding surface tension at the calculated plane, highlighting its applicability in understanding nanobubbles behavior. Notably, we observed that gas density has minimal impact on the surface tension of nanobubbles according to Young's equation. Overall, our research provides valuable insights into the generation of stable nanobubbles for diverse applications.