The electrochemical reaction mechanism of arsenic on gold analyzed by anodic stripping Square-wave voltammetry

ALICIA D. ROBLES; SABRINA N. VETTORELO; MARCELA GERPE; FERNANDO GARAY

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 vol. 227 p. 447 - 447

0013-4686

he reaction mechanism of the oxidative stripping of As(0) accumulated on a polycrystalline gold electrode is studied theoretically and experimentally by Square-wave voltammetry (SWV). A mathematical model was developed specifically to describe this reaction mechanism. A reaction scheme E(ad)C is considered in this model, where As(0) corresponds to the adsorbed reduced species. The electrochemical oxidation of As(0) produces a soluble species that undergoes a chemical reaction with pseudo-first order kinetics. Although the reduction of hydrogen at the electrode surface can contribute to the deposition of As(0), significant evolution of H2 would compromise this process. From the fits of experimental SW voltammograms, it is possible to estimate the value of the standard charge-transfer rate constant ks = (4 ± 2) s?1, α = (0.20 ± 0.01), the chemical reaction equilibrium constant K = 3×10-4, the adsorption constant Kad = 1×10-2, the formal potential of the redox step Eo? = (0.055 ± 0.