Wy. Hwang et Js. Shih, Properties and applications of cryptand-22 surfactant for ion transport and ion extraction, J CHIN CHEM, 47(6), 2000, pp. 1215-1222
A non-ionic cryptand-22 surfactant consisting of a macrocyclic cryptand-22
polar head and a long paraffinic chain (C10W21-Cryptand-22) was synthesized
and characterized. The critical micellar concentration (CMC) of the crypta
nd surfactant in ROH/H2O mixed solvent was determined by the pyrene fluores
cence probe method. In general, the cmc of the cryptand surfactant increase
d upon decreasing the polarity of the surfactant solution. The cryptand sur
factant also can behave as a pseudo cationic surfactant by protonation of c
ryptand-22 or complexation with metal ions. Effects of protonation and meta
l ions on the cmc of the cryptand surfactant were investigated. A prelimina
ry application of the cryptand surfactant as an ion-transport carrier for m
etal ions, e.g., Li+, Na+, K+ and Sr2+, through an organic liquid-membrane
was studied. The transport ability of the cryptand surfactant for these met
al ions was in the order: K+ greater than or equal to Na+ > Li+ > Sr2+. A c
omparison of the ion-transport ability of the cryptand surfactant with othe
r macrocyclic polyethers, e.g., dibenzo-18-crown-6, 18-crown-6 and benzo-15
-crown-5, was studied and discussed. Among these macrocyclic polyethers, th
e cryptand surfactant was the best ion-transport carrier for Na+, Li+ and S
r2+ ions. Furthermore, a foam extraction system using the cryptand surfacta
nt to extract the cupric ion was also investigated.