Abstract: EDTA was used to complex nickel to make the separation of trace amount of nick-el and cobalt possible by an emulsion liquid membrane containing P507-Span80-liquid paraf-fin-kerosene-HCl.Good results were obtained under conditions: pH = 4.6~5.2, ratio ofemulsion to solution=0.1, and separation time ca.20 min.Separated cobalt and nickel couldbe easily determined by spectrophotometer.Under these conditions the recoveries of cobaltand nickel were more than 95% and 13%, respectively, the coefficient of separation was over130.Membrane phase could be reused repeatedly.Among the coexisting ions, only Ca²⁺ and Cu²⁺ affect the separation.

Key words: colbalt, nickel, separation, liquid membrane, EDTA