Potentiometric investigations on the interaction of humic acid with Cu(II) and Eu(III) ions

摘要

The interaction of Cu(II) and Eu(III) ions with humic acid has been studied by potentiometry under normal atmospheric conditions at pH 6, I = 0.1 M (NaClO4) at room temperature (23 +/- 2 degrees C). The investigation was performed for the Cu(II) ion directly by means of a Cu2+ ion selective electrode, whereas for the Eu(III) ion it was indirectly based on competition reactions between the Cu(II) ion and the Eu(III) ion. The evaluation of the conditional formation constants, which was based on the charge neutralization model, resulted in as follows: log beta(Cu-HA(II)) = 5.6 +/- 0.3 log beta(Eu-HA(III)) 6.2 +/- 0.5.