Synthesis and evaluation of superior calcium and mercury transport by simple monocarboxylic acids of Kemp's triacid

Transport abilities of alkaline earth, transition, and heavy metal ions were examined for three kinds of disubstituted monoacid derivatives of Kemp's triacid as transport agents for a liquid membrane system. Diamide derivatives showed high transport ability for Ca-II over Mg-II, with selectivity ratios greater than 25. Imide monoacids were also Ca-II selective. For transition and heavy metal ions, all monoacids including diester monoacid showed very high Hg-II transport, but with different selectivities depending on the functional group. High Hg-II/Ag-I (= 24), Hg-II/Cu-II ( = 194), and Hg-II/Pb-II ( = 85) selectivities were observed for diamide, diester, and imide monoacids, respectively. The transport mechanisms are discussed for alkaline earth, transition, and heavy metal ions utilizing ion chromatography analysis of anions cotransported.