Studies on bubble dynamics with mass transfer

The dynamics and mass transfer of a single reactive bubble of carbon dioxide rising in a strong alkaline solution of sodium hydroxide has been investigated experimentally and numerically. A simple dynamic model of the bubble based on pressure balance, force balance and mass transfer considerations has been developed. The model assumes sphericity of bubble and considers added mass of liquid, drag and surface tension effects on bubble pressure. The effect of the accumulated contaminants on the mass transfer and drag coefficients are included in the model using an adaptation from literature. Photographic technique has been successfully used to follow the radius, and rise of the individual CO2 bubbles of radius ranging from 0.45 to 0.65mm rising in 4%, 6% and 10% (w/v) NaOH solutions. The rise velocity, drag coefficient, mass transfer coefficient and other parameters were calculated from the videograph. Limited deviation between model and experiments expressed as absolute deviation in radius (mean: 6.89%, maximum: 12%), velocity (mean: 8%, maximum: 24%), and rise (mean: 7.3%, maximum: 15%) is observed. The enhancement factor for the mass transfer with reaction, the cap angle of the accumulated contaminants and drag coefficient were calculated from the model.