Diamond electrodes applied to the voltammetric generation of nitro-anion radicals from methyl parathion in aqueous media

Electrochemical performance of methyl parathion (MP) at a boron-doped diamond (BDD) electrode was investigated in aqueous media by cyclic voltammetry (CV) and square wave voltammetry (SWV). Methyl parathion (MP) shows electroactivity on BDD electrodes, three peaks being registered corresponding to one oxidation (0.16 V) and two reduction peaks, at −0.53 V and 0.01 V. MP reduction is certainly pH-dependent. However, at pH > 9.0 the electrochemical reduction of MP involves a reversible reaction of one electron forming the nitro-anion radical (NAR). The nitro-anion radical undergoes disproportionation and its kinetic stability was evaluated by using a peak current ratio corresponding to the reversible pair R − NO2/R − NO2−, and the second-order constant (k2) was determined. Moreover, thermodynamic parameters regarding the MP reduction mechanism and nitro-anion radical generation were investigated by computational methods. [Display omitted] •Voltammetric generation of nitro-anion radicals in aqueous media•Theoretical study on the nitro-anion radical stabilization•Methyl Parathion electrochemical performance at a boron-doped diamond electrodes