作者:F. M. Menger、Jeng Jong Lee
DOI:10.1021/jo00059a050
日期:1993.3
Six long-chained ligands were synthesized and examined for their ability to transport Cu(II) through a liquid membrane. The transport was proton-driven and capable of moving metal ions ''up-hill''. The time-dependence of the Cu(II) concentrations was determined for each carrier and for all three phases of the liquid membrane system. Thus, it was possible to follow the transfer of Cu(II) from the aqueous source phase to the organic layer and from the organic layer to the aqueous receiving phase. In addition, relative partitioning equilibria of Cu(III) between the organic layer and the aqueous phases were compared. It was found that all transport rates were kinetically controlled. Of the six carriers, only one was truly effective (the others experiencing difficulties releasing Cu(II) into the receiving phase). This one carrier displayed a remarkable activity exceeding that of LIX63 (a 'standard' in industrial extractions from copper ore). The activity was attributed to the carrier bearing polar hydroxyls at the ligand end of molecule, thereby enhancing the affinity for the organic/water interface where the rate-determining reactions take place. Studies were carried out varying the pH of the aqueous phases, the carrier concentration, and the nature of the organic layer.