Enhancement of oxygen gas–liquid mass transfer with colloidal gas aphron dispersions

In this work, an attempt was made to enhance gas–liquid mass transfer of oxygen with the aid of colloidal gas aphron (CGA) dispersion. The gas–liquid volume mass transfer coefficients (kLa) of oxygen in CGA dispersions were measured and related to stirring velocity, type and concentration of surfactants, and temperature. Four surfactants, sodium dodecyl sulfate (SDS), hexadecyltrimethyl ammonium chloride (HTAC), nonylphenol ethoxylate (NP-10), and potassium mono lauryl phosphate (MAPK), were examined in forming CGAs and thereby affecting the mass transfer of oxygen in the dispersions. It was found that effects of surfactants on the oxygen gas–liquid mass transfer were type-dependent. As concentrations rose, the kLa of oxygen increased evidently for SDS and an enhancement of kLa by a factor of three was observed at the concentration of 2.75 g/L. However the kLa decreased for MAPK. Nonylphenol ethoxylate was found to have little effect on kLa and HTAC showed mixed behavior. In SDS dispersion, it was found that the mass transfer reached a maximum value at a stirring velocity of 8000 r/min, but further benefit was not observed afterwards. With the increase of temperature, the mass transfer of oxygen was intensified but no much benefit was observed above 308 K.