Surface Effects and Mass Transfer in Bubble Column

Absorption of CO₂ gas is carried out in a bubble column under a fixed gas flow rate. A small amount of surface-active additive in the column liquid has the effect of retarding the coalescence of gas bubbles, thus making the gas-liquid interfacial area, a, larger; it also has the effect of resisting the stretching or compression of the interface and reducing disturbance in the bulk fluids, therefore making the mass-transfer coefficient, k_L, smaller. Because of these two opposing factors, the product k_La has a maximum value at a very low surfactant concentration. The surface activity of the catlonic/anlonlc binary surfactant solution may be considerably higher than that of the solution containing a single surface active component. The application of this synergistic effect may prove to be a very effective way of improving the operating efficiency of the bubble column.