Mechanisms of Gas Desorption from Aqueous Solution

The desorption of CO from supersaturated water solution has been extensively studied using a string-of-spheres apparatus. Dissolved gas supersaturation, liquid flow rate, gas phase composition, and the nature of the solid spherical surfaces were varied. When the ratio of the partial pressure of dissolved gas to total system pressure was below unity, mass transfer was purely diffusional whereas for values of this ratio greater than unity, desorption was accompanied by the rapid generation of gas bubbles. Spheres which were artificially roughened gave higher bubbling desorption rates than smooth polished spheres. No such differences were detected in the absence of bubbling. Mass transfer coefficients were found to be higher for absorption than for non-bubbling desorption.