To encapsulate extractants by method of microencapsulation can solve the problems of phase dispersion

phase mixing

phase separation

the leakage of extractant

as well as complicated structure of equipment in the extraction process．In the present work polysuffone and polystyrene as polymer materials were used to encapsulate the extractants such as TBP

D2EHPA

TOA

Aliquat 336 etc by means of solvent evaporation．The influence of shell materials

dispersants

stirring speed and composition of the organic phase has been investigated．The experimental results showed that TBP and D2EHPA were successfully encapsulated with polysulfone as the shell material while for the preparation of TOA and Aliquat 336 the shell material of polystyrene should be applied．The spherical shape and monodispersity of the microcapsules were related to the dispersion agent used in the O/W system．The mean diameter of the microcapsules decreased greatly with an increase of the stirring speed．Besides the stirring speed

the viscosity of polymer solution and the interfacial tension of working systems are the major factors that influence the size of the microcapsules．An optimal encapsulation efiqciency of the mierocapsules was reached when the content ratio of the shell rnaterial to the extractant in the polymet solution was optimized．