Quantitative description of macrocycle-mediated cation separations in liquid membranes and on silica gel as a function of system parameters

R. M. Izatt, R. L. Bruening, J. S. Bradshaw, J. D. Lamb, J. J. Christensen
1988 Pure and Applied Chemistry  
A b s t r a c t -Cation t r a n s p o r t by both n e u t r a l and p r o t o n -i o n i z a b l e macrocycles i n l i q u i d membranes is often diffusion limited. Extraction constants, d i s t r i b u t i o n c o e f f i c i e n t s , aqueous phase macrocycle-cation and a n i o n -c a t i o n i n t e r a c t i o n c o n s t a n t s and membrane geometry a r e t h e parameters i n the diffusion limited transport equations. On the other hand, the behavior of cation solutions i n s i l i c a gel
more » ... columns containing bonded macrocycles can be described using homogeneous phase macrocyclecation equilibrium constants and column geometry a s modeling parameters. Examples from our recent work a r e given t o show how separation processes can be designed from an understanding of t h e s e parameters. The separations of Sr(I1) from Ba(I1) and of H g ( I I ) , C d ( I 1 ) and Zn(I1) from each other using 18-crown-6 type macrocycles and the separation of Ag(1) from P b ( I 1 ) using pyridono and t r i a z o l o type macrocycles a r e described. The i n f l u e n c e of macrocycle, solvent, cation and anion types on t h e parameters is examined i n discussing these examples.
doi:10.1351/pac198860040453 fatcat:j4ukg3dbrrbwzkrpb5jl2yr6tq