title: Roles of dynamic metal speciation and membrane permeability in metal flux through lipophilic membranes: general theory and experimental validation with nonlabile complexes.
abstract: The study of the role of dynamic metal speciation in lipophilic membrane permeability in aqueous solution requires accurate interpretation of experimental data. To meet this goal, a general theory is derived for describing 1:1 metal complex flux, under steady-state and ligand excess conditions, through a permeation liquid membrane (PLM). The theory is applicable to fluxes through any lipophilic membrane. From this theory, fluxes in the three rate-limiting conditions for metal transport are readily derived, corresponding, namely, to (i) diffusion in the source solution, (ii) diffusion in the membrane, and (iii) the chemical kinetics of formation/dissociation of the metal complex in the interfacial reaction layer. The theory enables discussion of the reaction layer concept in a more general frame and also provides unambiguous criteria for the definition of an inert metal complex. The theoretical flux equations for fully labile complexes were validated in a previous paper. The general theory for semi- or nonlabile complexes is validated here by studying the flux of Pb(II) through PLMs in contact with solutions of Pb(II)-NTA and Pb(II)-TMDTA at different pHs and flow rates.
authors: CABE, Department of Inorganic, Analytical and Applied Chemistry, University of Geneva, Sciences II, 30 quai E. Ansermet, CH-1211 Geneva 4, Switzerland.
authors: Zeshi
authors: Z
authors: Zhang
authors: Jacques
authors: J
authors: Buffle
authors: Herman P
authors: HP
authors: van Leeuwen
mesh_terms: D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007854:Lead / Q000737:chemistry*; D008024:Ligands; D008055:Lipids / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical; D009571:Nitrilotriacetic Acid / Q000737:chemistry*; D010539:Permeability; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D008024:Ligands; D008055:Lipids; D008567:Membranes, Artificial; D012996:Solutions; D014867:Water; D007854:Lead; D009571:Nitrilotriacetic Acid