THE FORMATION AND GROWTH OF CARBON-DIOXIDE GAS-BUBBLES FROM SUPERSATURATED AQUEOUS-SOLUTIONS

A simple stopped-flow apparatus has been devised to follow the growth of gas bubbles formed after the rapid establishment of a supersaturate d aqueous carbon dioxide solution by the reaction of hydrogen ions wit h bicarbonate ions. Turbidimetric measurements taken over a period of c.200 ms, supplemented by analysis of photographic and videotape recor dings at later times have shown that bubble growth is a diffusion-limi ted process. Experimental results obtained with a hydrophobised cell l ed to the conclusion that at supersaturations typical of carbonated be verages the mechanism of bubble formation probably involves pre-existi ng gas cells trapped on the surface. Adsorption of sodium dodecyl sulp hate, beta-casein or beta-lactoglobulin onto the hydrophobic surface r educed the number of bubbles, but solutions of sodium dodecyl sulphate above the critical micelle concentration produced additional bubbles.