Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

An orientational study is presented of the pulse polarographic features of Pb²⁺ and Cd²⁺ in aqueous solutions of polymethacrylic acid, partially esterified. Normal pulse polarography with varying pulse duration was applied, and the resulting Cottrell plots were used to check the diffusion-controlled character of the currents. Values for binding constants under various conditions are presented. It could be established that the binding of Pb²⁺ increases with decreasing Pb²⁺/PMA ratio, which is a typical polyelectrolytic effect. It is in accordance with indications from Henderson-Hasselbalch analysis of the NPP current data. Variation of the pH, corresponding with variation of the overall charge on the polymer, confirms the polyelectrolytic character of the binding. The latter finding is also supported by indications from experiments at different electrolyte concentrations. At rather negative initial potentials and sufficiently low Cd²⁺/PMA ratio the polarograms for Cd²⁺ show the maxima which are typical for induced reactant adsorption.