Patent Number: 044773773
Section: summary

INTRODUCTION The present invention relates to recovery of cesium ions from mixtures thereof with other ions by establishing a separate basic source phase containing the ions to be separated, including cesium ions, a separate recipient phase and a liquid membrane phase containing a macrocyclic polyphenol (calixarene) ligand in a liquid membrane solvent interfacing with said source and recipient phases, maintaining the interface contact for a period of time long enough to transport a substantial part of the cesium ions from the source phase to the recipient phase and recovering the cesium ions from the recipient phase. The process may be referred to as the selective transport of Cs+ through a liquid membrane by a macrocyclic polyphenol or calixarene ligand. BACKGROUND OF THE INVENTION The cyclic polyphenols comprising a ring of monomer units having the structures depicted in the drawing, first reported by A. Zinke and E. Ziegler, Chem. Ber., 77, 264-272 (1944), are somewhat similar in structure to the cyclic polyethers and other macrocyclic ligands which are characterized by their size-related selectivity in binding cations noted in J. D. Lamb, R. M. Izatt, J. J. Christensen, D. J. Eatough, COORDINATION CHEMISTRY OF MACROCYCLIC COMPOUNDS, edited by G. A. Melson, Plenum, pages 145-217 (1979). The synthetic chemistry of compounds of this type has received careful study, expecially by Gutsche and his coworkers, who have designated these compounds calixarenes, C. D. Gutsche, R. Muthukrishnan, J. Org. Chem. 43, pages 4905-4906 (1978). Synthesis of cyclic heptamers of similar structure has been reported by H Kammerer and G. Happel, Makromol.Chem. 181, pages 2049-2062 (1980) and of cyclic pentamers by A. Ninagwa and H. Matsuda, Makromol.Chem.Rat.Comm.3, pages 65-67 (1982). The oligomeric hexameric and tetrameric compounds depicted in the drawing have been described by C. D. Gutsche, B. Dhawan, K. H. No and R. Muthukrishnan, J. Am. Chem.Soc.,103, pages 3782-3792 (1981). Such compounds are Bronsted-Lowry acids which E. M. Choy, D. F. Evans, E. L. Cussler, J. Am.Chem.Soc.,96, pages 7085-7090 (1974) used successfully to drive the flux of Na+ against the concentration gradient of monensen. SUMMARY OF THE INVENTION The invention is based on the discovery that calixarenes are very effective as membrane carriers of cesium cations. They are characterized by a high degree of transport selectivity for Cs+ over other alkali metal cations, a low solubility in water, which minimizes loss to adjacent water phases, and the formation of neutral cation complexes through loss of a proton so that the anion does not need to accompany the cation through the membrane. This latter property makes it possible to couple the transport of cations in the reverse flux of protons through the membrane.