Air was fed into a packed extraction column to increase turbulence

enhance liquid droplet dispersion and surface renewal

and thus raise mass transfer area.This led to improvement of liquid-liquid contact and mass transfer.The experiments on hydrodynamics and mass transfer were carried out with air-kerosene (benzoic acid)-water system

and the effect of air agitation was investigated.It is clear from the results that the air hold-up

dispersed phases hold-up and mass transfer coefficient increase and flooding velocity goes down while increasing superficial air velocity.The over-agitation of air can cause over-dispersion and emulsification of the dispersed phase

deterioration of mass transfer performance

and even flooding.Packing helps to break up the droplet of dispersed phase and can effectively prevent the liquid from longitudinal mixing in extraction column

so the mass transfer performance of packed column is far better than that of non-packed.