Prediction and Experimental Study of Mass Transfer Properties of Micronanobubbles

In order to study the mass transfer efficiency of micronanobubbles (MNBs), an equation of the volumetric mass transfer coefficient (k(L)a) was proposed based on theory and dimensionless numbers. It was verified by experimental data from different literature sources. Then, the k(L)a in an MNB column was measured under the conditions of different salt concentrations. The test results showed that the equation could successfully predict the k(L)a in an MNB column of not only this research but also other literature. In the MNB column, when the salt concentration increased from 0.0 to 3.0 g/L, the values of the Sauter mean bubble diameter (d(BS)), gas holdup (epsilon), and specific gas-liquid interface (a) had remarkable changes. Salt coalescence suppression was the governing effect for the hydrodynamic variables, and it was more prominent for common bubbles than for MNBs. value of the k(L)a in the MNB column was an order of magnitude larger than that in the common bubble column, and it was improved significantly in salt solution. Hydrodynamic variables were dominant effects of mass transfer. Overall, the prediction equation of the k(L)a provides a reference for the mass transfer rate calculation of MNBs.