The Contribution of Bubbles to Gas Transfer Across an Air-Water Interface

Abstract

A first theoretical approach to gas transfer by bubbles is undertaken. It is found that transfer velocity increases when solubility decreases. Bubble over-pressure leads to water supersaturation at equilibrium, this supersaturation being more significant for less soluble gases. Although the transfer velocity remains roughly constant for a variable concentration far from equilib rium, its range of variation becomes infinite near equilibrium. Attention is turned directly to the flux itself: it is shown that the flux is a linear function of the concentration gradient. At least for tracers, the coefficients of this function are entirely defined by the physico-chemical properties of the gas and by the bubble distribution.