Impact of pH on the Anodic Current-Voltage Characteristics of the Alkaline Cu ∣ Cu (II), Glycine System

Abstract

Anodic voltammograms using rotating disc electrode (RDE) and linear sweep (LS) techniques were obtained for alkaline (9 < pH < 11.2) Cu (II)-glycine solutions. The nature and properties of the RDE anodic pseudo-limiting currents i lim and LS peak currents i p were considered within the framework of a theoretical model, taking into account the peculiarities of mass transfer of chemically interacting species. Both i lim and i p increase with solution pH and vary linearly with the concentration of glycinate anion l−. The degree of irreversibility of the process significantly affects the i p values, but has only small influence on i lim. Both characteristic current densities could serve as a measure of deprotonated ligand species, which is capable of forming stable Cu (II) complexes. The applications of modified equations, which were derived for i p in the case of simple redox systems, are discussed in detail.

Analysis of Anodic Linear Sweep Voltammograms Considering Insufficient Lability of Cu|Cu(II), Glycine System

“…As noted above, these plots can imitate stationary voltammograms, since the Δc M is proportional to the anodic current density. Experimental studies 25,33,37,38 confirm the presence of plateau-like limiting currents on RDE voltammograms. They occur as cathodic pre-waves in ligand-deficient systems or as anodic pseudo-limiting currents when there is an excess of ligand in solutions.…”

“…In this paper, we analyze the anodic behavior of the system using a similar approach. Along with the original experimental data, we also consider some anodic LS voltammograms, which were presented earlier, 33 but were not subjected to kinetic analysis.…”