The resistance of interphase mass transfer in colloidal liquid aphron systems

Colloidal liquid aphrons (CLAs) provide very large interfacial area and thus could enhance interphase mass transfer in multiphase processes. This work characterized the mass transfer behavior of CLAs during mass transfer of benzoic acid from cyclohexane in CLAs to water in a small stirred vessel. From experimental data the overall mass transfer coefficient KLKL of the surfactant-stabilized CLAs was determined. The influence of stirring speed and concentration of surfactant used for formulating CLAs on KLKL was investigated. The experimental results show that surfactant adsorbed on the interface of CLAs influences greatly the value of KLKL, and when the surfactant concentration is below its CMC, the overall CLAs mass transfer coefficient KLKL (mainly varying with the interfacial mass transfer resistance) could be fitted to the following expression:KL=H1+H2ln[C+H3].KL=H1+H2ln[C+H3].When the surfactant concentration is above its CMC, it is found that the influence of surfactant on diffusion resistance was dependent on its type. For the non-ionic surfactant, the increase of surfactant concentration has little influence on diffusion resistance. However, for the ionic surfactant, the overall CLAs mass transfer coefficient KLKL (mainly varying with the diffusion resistance) decreases approximately in a linear way as the concentration of ionic surfactant is increased. These correlations represent the experimental data satisfactorily.