  Bubble solutions are of growing interest because of various technological
applications in surface cleaning, water treatment, and agriculture. However,
their physicochemical properties such as the stability and interfacial charge
of bubbles are not fully understood yet. In this study, the kinetics of radii
in aqueous microbubble solutions are experimentally investigated, and the
results are discussed in the context of Ostwald ripening. The obtained
distributions of bubble radii scaled by mean radius and total number were found
to be time-independent during the observation period. Image analysis of radii
kinetics revealed that the average growth and shrinkage speed of each bubble is
governed by diffusion-limited Ostwald ripening, and the kinetic coefficient
calculated using the available physicochemical constants in literature
quantitatively agrees with the experimental data. Furthermore, the cube of mean
radius and mean volume exhibit a linear time evolution in agreement with the
Lifshitz-Slezov-Wagner (LSW) theory. The coefficients are slightly larger than
those predicted using the LSW theory, which can be qualitatively explained by
the effect of finite volume fraction. Finally, the slow down and pinning of
radius in the shrinkage dynamics of small microbubbles are discussed in detail.
