Theoretical and experimental study of the catalytic cathodic stripping Square-wave voltammetry of chromium species

MARIELA CUÉLLAR; SABRINA N. VETTORELO; PATRICIA I. ORTIZ; FERNANDO GARAY

JOURNAL OF SOLID STATE ELECTROCHEMISTRY (PRINT)

SPRINGER

Lugar: Berlin; Año: 2016 p. 1 - 1

1432-8488

he electrocatalytic mechanism of Cr(III) reduction in presence of diethylenetriaminepentaacetic acid (DTPA) and nitrate ions is studied theoretically and experimentally by using stripping Square-wave voltammetry (SWV). Experimental curves are in excellent agreement with theoretical profiles corresponding to a catalytic reaction of second kind. This type of mechanism is equivalent to a CE mechanism, where the chemical reaction produces the electroactive species. Accordingly, the reaction of Cr(III)-H2O-DTPA and (NO3)2- would produce the electroactive species Cr(III)-NO3-DTPA and this last species would release (NO2)2- to the solution during the electrochemical step. In this regard, the complex of Cr(III)-DTPA would work as the catalyzer that allows the reduction of (NO3)2- to (NO2)2-. Furthermore, it was found that the electrochemical reaction is quite irreversible, with a constant of ks = 9.4×10^-5 cm s-1, while the constant for the chemical step has been estimated to be kchem = 1.3×1