Back to Search
Start Over
Theoretical and experimental study of the catalytic cathodic stripping square-wave voltammetry of chromium species.
- Source :
-
Journal of Solid State Electrochemistry . Dec2016, Vol. 20 Issue 12, p3279-3286. 8p. - Publication Year :
- 2016
-
Abstract
- The electrocatalytic mechanism of Cr(III) reduction in the 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)-HO-DTPA and $$ {\mathrm{NO}}_3^{-} $$ would produce the electroactive species Cr(III)-NO-DTPA and this last species would release $$ {\mathrm{NO}}_2^{-} $$ 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 $$ {\mathrm{NO}}_3^{-} $$ to $$ {\mathrm{NO}}_2^{-} $$ . Furthermore, it was found that the electrochemical reaction is quite irreversible, with a constant of k = 9.4 × 10 cm s, while the constant for the chemical step has been estimated to be k = 1.3 × 10 s. Considering that the equilibrium constant is K = 0.01, it is possible to estimate the kinetic constants of the chemical reaction as k = 1 × 10 s and k = 1.29 × 10 s. These values of k and k indicate that the exchange of water molecules by nitrate is fast and that the equilibrium favors the complex with water. Also, a value for the formal potential E°' ≈ −1.1 V was obtained. The model used for simulating experimental curves does not consider the adsorption of reactants yet. Accordingly, weak adsorption of reagents should be expected. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14328488
- Volume :
- 20
- Issue :
- 12
- Database :
- Academic Search Index
- Journal :
- Journal of Solid State Electrochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 119576922
- Full Text :
- https://doi.org/10.1007/s10008-016-3307-3