Efficient facilitated transport of lead, cadmium, zinc, and silver across a flat-sheet-supported liquid membrane mediated by lasalocid A

Flat-sheet-supported liquid membranes incorporating lasalocid A (a natural ionophore) were shown in previous works to achieve the transport of divalent transition metal cations such as Cd2+ and Zn2+ against a proton gradient, which is the driving force behind the process. This transport process has been extended to other metal species such as Pb2+ and Ag+ and also to the case where the two metal species compete for transport. A higher transport flux for Pb2+ as compared to Cd2+ and Zn2+ is observed, which is partly explained by a higher rate of interfacial complexation due to a smaller hydration shell of this species. This effect is confirmed by the data obtained with Ag(I).