Fluorescence-Indicated Mass Transfer in Reactive Extraction

Abstract

To investigate mass transfer into droplets in reactive extraction, a nonintrusive method for measuring concentration gradients using fluorescent dyes as sensors was developed. An optical probe is used to focus a laser beam into the droplet and to detect the fluorescent light. Scanning the droplet with the probe leads to concentration profiles. The added dyes can either be indicators to measure gradients of ionic components in the aqueous phase or be one component of the extraction system. For the description of the system ZnSO 4 -H 2 SO 4 /di(2-ethylhexyl)phosphoric acid in isododecane, experiments have been carried out in the stagnant as well as in the flowing continuous phase. To investigate the effects of internal circulation in the droplets, further mass transfer experiments in a venturi tube have been carried out. A comparison enables both diffusion and convection inside and outside of a droplet in a reactive system to be described.

Laser‐Induced Fluorescence in Multiphase Systems

“…Mörters and Bart [95] investigated diffusion processes within and around droplets with and without chemical reaction by mens of an optical probe. They determined diffusion coefficients and described the mass transfer behavior for both stagnant and flowing continuous phase.…”