Role of Mutual Diffusion in the Dissolution Behavior of One Primary Bulk Gas Nanobubble in Liquid: A Molecular Dynamics Study

Dissolution of one primary bulk gas nanobubble in an
undersaturated
liquid constitutes one of the underlying issues of the exceptional
stability of bulk gas nanobubble population. In this paper, the mutual
diffusion coefficient at the gas–liquid interface of one primary
bulk gas nanobubble is investigated via all-atom molecular dynamics
simulation, and the applicability of the Epstein–Plesset theory
is verified. The mutual diffusion coefficient, different from the
self-diffusion coefficient in bulk gas or bulk liquid, is essentially
determined by the chemical potential due to its driving role in the
mass transfer across the interface. We could ascribe the low-rate
dissolution of one primary bulk gas nanobubble in an undersaturated
liquid to the slight attenuation of the mutual diffusion coefficient
at the interface. The results show that the dissolution process of
one primary bulk gas nanobubble in an undersaturated liquid fundamentally
obeys the Epstein–Plesset theory and that the macroscopic dissolution
rate is intrinsically determined by the gas mutual diffusion coefficient
at the interface rather than the self-diffusion coefficient in the
bulk phase. The mass transfer viewpoint from the present study might
actively promote subsequent studies on the super-stability of bulk
gas nanobubble population in liquid.