Experimenting with liquid membranes

Cation fluxes from binary Ag+-Mn+ mixtures in a water-trichloromethane-water liquid membrane system containing a series of macrocyclic ligand carriers

“…Other workers have confirmed his findings. 11,203,21 In view of the affinity of Ag+ for either nitrogen or sulfur donors and the relatively low affinity of alkali cations for these donors, the transport results are not surprising. The enhanced stability of the Ag+ complexes, as well as the lower stability of the M"+ complexes, led to the selective transport of Ag+ in the alkali and alkaline earth binary systems.…”

“…Log K values valid in water for the reactions of closely related (e.g., alkali metal) cations with a given macrocycle differ from those valid in methanol by a nearly constant amount, ~3,7,11 and we assume that the values obtained in these two solvents reflect the trends valid in CHC13 for correlation with transport results in our membrane systems. Previous results show that the ligand donor atom type, the cation-ligand cavity size ratio, and ligand ring substituents can markedly affect the magnitude of log K.19-23 As 600-606. would be expected, these effects are reflected in the relative fluxes of the cations.5'10•* 11 Maximum transport in liquid membrane systems of the type used here occurs when K values for M"+-macrocycle complexation fall within a certain range.7•18 If K is sufficiently low, cations are not extracted from the source phase into the membrane. On the other hand, if K is sufficiently large, cations are not released from the membrane into the receiving phase.…”

“…In addition, the solubility of the lipophilic crown ethers in many organic extension of this latter use has been the investigation of the selective transport by crown ethers of cations from a source aqueous phase across a liquid organic membrane and into a receiving aqueous phase. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In earlier studies, we correlated the macrocycle-mediated transport of single cations across a H20-CHC13-H20 liquid membrane with a variety of system parameters including ratio of ligand cavity radius to cation radius, cyclic vs. noncyclic ligands, ligand donor atom type, ligand ring substituents, relative ligand solubilities in H20 and CHC13, cation charge, and cation type. 10 In addition, we have determined cation fluxes, JM (mol/(s m2)), in these membrane systems when two metal nitrate salts are initially present in one aqueous phase.…”

Calix[4]arene Amino Acid Derivatives. Intra- and Intermolecular Hydrogen-Bonded Organisation in Solution and the Solid State

“…Transport measurements: Thomans [25] modification of the procedure described by Lamb et al [26] was used to measure the rates of ion transport through a dichloromethane membrane. The membrane (CH 2 Cl 2 , 10 mL, 7 Â 10 À4 m of the calixarene derivative) was placed in a 70 mL beaker, which contained a magnetic stirring bar.…”

Amphiphilic metalloaggregates: Catalysis, transport, and sensing

“…an organic solvent separating two aqueous phases [60]. For this reason and for the relevant applications in the field of species separation, this membrane model has been widely used in transport studies [61].…”