Effects of Surfactants on Mass Transfer from Single Carbon Dioxide Bubbles in Vertical Pipes

Mass transfer from single fully contaminated carbon dioxide bubbles rising through vertical pipes was measured to investigate the effects of surfactants. The diameter ratio of the bubble diameter to the pipe diameter was varied to cover various bubble shapes from ellipsoidal to Taylor bubbles. Triton X‐100 and 1‐octanol served as surfactants. The mass transfer rates, kL, of contaminated bubbles in the ellipsoidal regime were smaller than those of clean bubbles due to the interface immobilization. The kL of Taylor bubbles contaminated with Triton X‐100 and 1‐octanol showed varying trends because of the difference in the surfactant distributions at the bubble interfaces which strongly depend on the Hatta number. The Sherwood numbers of contaminated bubbles were well correlated by introducing the bubble diameter, at which the bubble shape transits from ellipsoidal to Taylor bubbles. To investigate the effects of surfactants, mass transfer rates, kL, of single CO2 bubbles rising through contaminated water in vertical pipes are measured. The Hatta number plays a key role in interfacial distribution of surfactant, on which kL strongly depends. A kL correlation applicable to fully contaminated ellipsoidal and Taylor bubbles is proposed.