A review with 44 refs. covering crown ethers, calixarenes, calyx-crown-arenes, and acyclic polyethers as surfactants in solvent extn., transport across liq. membranes, and ion flotation, esp. competitive ion flotation of Zn(II) and Cd(II); and Cs-137, Sr-90, and Ba-133 with ionizable lariat ethers; solvent extn. of Li and Be groups cations with ionizable dibenzo crown ethers and acyclic polyethers; calixarenes as ion carriers in liq. membrane transport; and competitive transport of Li and Be groups cations in permeation through liq. membranes.