Chlorate Electrochemical Removal from Aqueous Media Based on a Possible Autocatalytic Mechanism
Résumé
The electrochemical chlorate reduction at the Pt electrode in 0.5 M H
2SO 4 deaerated solutions has been
studied using potentiostatic steady-state voltammetry. The kinetics parameters (Tafel slope, charge transfer
coefficient, current density, and reaction order) were evaluated in function of chlorate concentration (1x10-
4 – 0.2 M KClO
). The process of chlorate reduction is a complex one that implies two charge transfer 3
controlled steps with formation of free radicals and an extent potential region controlled by the concentration
polarization. The current density dependence of chlorate concentration tends to an exponential growth at
concentration ≥ 0.1 M KClO
3 and becomes exponential in the conditions of the Cl−3/Cl− catalyst system
presence. In the second charge transfer, a surface reaction between free radical ·Cl- 2and platinum electrode
with formation of complex anions PtCL 42- and PtCL 62- is responsible for the rapid increase of the reaction
rate.