Extraction of potassium ion from an alkaline source phase containing high concentration of sodium ion through a chloroform phase facilitated by the lipophilic carrier crown ether 2-sym-(dibenzo-19-crown-6-oxy) decanoic acid was studied at 298 K by bulk liquid membrane and by liquid surfactant membrane experiments. Differences in the transport rate and efficiency were observed and discussed for the two separation techniques.185440443