Anomalous Stability of Carbon Dioxide in pH-Controlled Bubble Coalescence

摘要

Gas bubbles are formed as cavities in liquids, their pressure, shape, and deformability determined by the surface tension of the liquid. They are vital components in foams, microfluidics, sonochemical reactions, generation of atmospheric aerosol, and in the scent and taste delivery of soft drinks, beers, and champagne. In all of these cases, their stability or coalescence during inter-bubble collisions is a vital factor in determining bubble behavior and lifetime. It has been noted previously that, due to its high water-solubility and unusual aqueous chemistry, carbon dioxide may be expected to behave differently than inert gases, suggesting that a comparative study is needed. Here, we explore bubble coalescence as a function of pH and gas type, demonstrating that CO2 has a suprising and vital role, by comparing pure CO2 bubbles with air (which has CO2 as a minor component), argon, and nitrogen (pure, inert gases).