Liquid-liquid extraction columns

A method of quantifying the degree of Marangoni instabilities (and hence droplet-continuous phase interfacial turbulence) in a column-type liquid-liquid extraction system comprises operating the system with varying continuous and/or dispersed phase superficial velocities, measuring hold-up X of the dispersed phase at the different superficial velocities and analysing the measurements in terms of an equation which allows for Marangoni instability in terms of an exponential factor of the form exp (MX) where M is a measure of Marangoni instability which can be derived from a semi-logarithmic plot of the equation.