New sulphur-containing reagents as carriers for the separation of palladium by solid supported liquid membranes

N2-substituted N1-phenylbenzamidines and N′-disubstituted N-benzoyl thiourea derivatives, which contain donor S, N and O atoms, have been studied as carriers for the facilitated transport of Pd(II). These reagents have been shown to be effective in the solvent extraction of palladium. Thiocyanate ions or thiourea have been employed as stripping agents. The use of these reagents as carriers in liquid membranes was carried out by developing both bulk and supported liquid membranes. The presence of NaSCN in the feed solution at appropriate concentration results in an increase in the rate and mass transfer of palladium. N-benzoyl thiourea derivatives have been shown to be the most effective for Pd(II) transport and several compounds with enhanced lipophilic characteristics were prepared. A comparison of the results obtained reveals a significant influence of lipophilicity (side chain substituent) on the permeability of Pd(II). © 1994.