Surfactant effects on the equipment performance of extraction columns

A small amount of surface active agent in a extraction column has the effect of decreasing mass transfer coefficient, while increasing the mass transfer area. The overall mass transfer efficiency is thus varied complicatedly with the surfactant concentration and the hydrodynamic behavior of the two phase in the extraction columns. In this work, spray-tower and packed-tower are used as extraction columns to obtain the overall performance of the equipment. The effects of surfactant on the mass transfer efficiency and interfacial area in the two apparatuses are studied. The results show that the effects of SLS on the decreasing of mass transfer coefficient is more prominent than that on the increasing of mass transfer area in the both apparatuses. In the packed-tower, a higher efficiency is obtained due to the effect of the packing. However, at the presence of SLS, the dispersion effect can not raise the interfacial area high enough to overcome the simultaneous decrease in mass transfer coefficient. The mechanisms to increase interfacial area by the surfactant are different at various concentrations of SLS and different between the two apparatuses, which are also discussed in this article.