Electrochemical oxidation of nitrite: Kinetic, mechanistic and analytical study by square wave voltammetry

The voltammetric determination of nitrite is in principle a very competitive method by virtue of being fast, easy to apply, economical and portable. In order to optimize the experimental conditions for the analytical determination it is essential to understand the reaction scheme and kinetics of the redox system. With this purpose, in this paper square wave voltammetry is employed to examine the electro-oxidation of nitrite. The reaction mechanism and electrode kinetics are investigated, pointing out the effects of the solution pH, the electrode material (glassy carbon, edge plane pyrolytic graphite and gold) and the supporting electrolyte. A second order catalytic mechanism justifies the experimental results, with the nitrite being regenerated by disproportionation of the electrogenerated NO2 with a rate constant kdisp = (2.0 ± 0.1) × 106 M−1 s−1. The electrode reaction is found to be reversible on gold macroelectrodes and much slower on carbon based electrodes with blocking effect due to the presence of perchlorate anions.

► Electro-oxidation of nitrite is investigated with square wave voltammetry.
► Second-order catalytic mechanism is identified with inner-sphere electron transfer.
► Disproportionation rate constant for NO2 of k = 2 × 106 M−1 s−1 is obtained.
► Electron transfer is reversible on gold electrodes and slower on EPPG and GC.
► Perchlorate anions have blocking effect on the electron transfer at carbon electrodes.