Modeling Mass Transfer During Single Organic Droplet Formation and Rise

Abstract

Copper reactive extraction from ambient aqueous solution to organic droplets using single droplet experiments was performed. Extractant was Agorca M5640 hydroxyoxime in Exxsol D80. An image analysis based method was used to determine droplet concentration directly after droplet formation and rise. Mass transfer during formation is correlated using literature. Level Set interface tracking method was used to find formation hydrodynamics and as a result the assumption of non-circular velocity field could be validated. This was also supported by the circulation criteria based on needle Reynolds number. A model to estimate extraction rate as function of droplet Fourier number was based on a literature correlation and it was found that a model where the interface effect was described using interface mobility parameter was able to predict satisfactorily mass transfer. For a rising droplet stagnant cap model was used. Stagnant cap volumes were estimated from droplet images. A CFD model of a non-deforming rising droplet with rigid interface was used to fit interfacial reaction kinetic constant. Fitted value was much lower than experimentally determined by high a shear reactor. Mass transfer coefficients calculated from CFD model and estimated using literature correlations agreed well. By applying a two-film model it was shown that major part of the resistance is located at the interface between the phases.