(177e) The Effect of Interfacial Phenomena On Fluid Dynamics and Mass Transfer of Single Droplets

In the chemical industry liquid/liquid extractions occur frequently. For the fundamental understanding of these complex processes the smallest transfer unit is investigated in this work: single droplets. The important transport processes take place at the interface between the single droplet (dispersed phase) and the continuous phase. Hence, the understanding of the occurring interfacial phenomena is of special interest.  

In pure systems mass transfer induced Marangoni convection is influencing the fluid dynamics of single droplets and also improving the mass transfer significantly. In industrial applications interfacial active substances (e.g. surfactants) will often occur. These substances absorb at the interface reducing its mobility and forming an additional mass transfer resistance. Furthermore, these substances are able to exert an additional Marangoni convection. Mostly the presence of those substances is unintended and will occur due to impurities, but sometimes the presence of interfacial active substances is on purpose e.g. in micellar reactions. At high surfactant concentrations these molecules will agglomerate to micelles. These agglomerates are capable to solubilize the transferred component.

Hence, interfacial active substances are able to influence the mass transfer in many different ways. The analysis of these mechanisms and their corresponding influences on mass transfer processes is the main goal of this work. Therefore, experiments with different model systems have been carried out. The experiments show the influence of interfacial phenomena on fluid dynamics and mass transfer of single droplets.

The gained understanding of the interfacial phenomena shall be implemented in the models for the complex momentum and mass transport processes.