Visualization of Micro-Scale Bubble Dynamics in Pure Liquids and Aqueous Surfactant Solutions

Abstract

Growth and departure of a single adiabatic bubble in pure liquids and aqueous surfactant solutions is visualized. High-resolution photographic records are obtained that characterize the micro-scale bubble dynamics (shape, size, and post-departure translation), the mean bubble diameter at different time periods of its growth and departure, and the bubble surface age (the time interval from the newly formed interface to the attainment of departure diameter). This pre- and post-departure dynamics of air bubbles is visualized in water, N, N dimethyl-formamide (DMF), and ethyl alcohol (all pure liquids), and aqueous surfactant solutions of SDS (1250 wppm, 2500 wppm, and 5000 wppm), CTAB (200 wppm), and Triton X-305 (1000 wppm). The evolution of different bubble shapes, sizes, and departure frequencies is presented to highlight the effects of surface-active forces. In the case of surfactant solutions, the dynamic effects of the molecular-scale adsorption-desorption dynamics of the additive at the liquid-air interface that manifests in the dynamic surface tension is also delineated.