A kinetic study of the electrochemical oxidation of maleic acid on boron doped diamond

Abstract

Maleic acid (MA) is one of the main intermediates formed during mineralization, by electrooxidation, of aromatic compounds contained in aqueous wastes. This work investigates oxidation of maleic acid with or without the presence of oxalic acid (OA) and formic acid (FA) in aqueous solution by using boron-doped diamond (BDD) electrodes. OA and FA are the main products formed in MA electrooxidation. Voltammetric studies conducted with a BDD electrode of small surface (0.196 cm 2 ) show that MA oxidation takes place at a potential very close to that of the discharge of water. But, under potentiostatic conditions and at concentrations higher than 0.001 M, adsorption of MA blocks its own oxidation. Oxalic and formic acids are oxidized before the discharge of water. Again, the presence of maleic acid blocks the oxidation of formic and oxalic acids. Galvanostatic electrolyses of aqueous solutions of MA, OA, FA and mixtures of theses acids were conducted on a BDD electrode. Electrolyses were controlled by measurements of Total Organic Carbon, Chemical Oxygen Demand and by Liquid Chromatography. Results showed that MA was totally mineralized; FA and OA were very low concentration intermediaries. Electrolyses of solutions containing MA, initially in the presence of OA or FA, showed that the OA was oxidized at the same rate as the MA, whereas the FA oxidation began only when the MA had completely disappeared. These results suggest that OA oxidizes by a mass transport limited process coupled with a direct electron transfer with the anode. Under galvanostatic conditions, maleic acid and formic acid are probably oxidized via OH • radicals generated by water discharge.

Mineralization of organic pollutants by anodic oxidation using reactive electrochemical membrane synthesized from carbothermal reduction of TiO2

“…Hydroxyl radicals generated at the surface of a BDD anode are able to participate to the oxidation of OA (Martınez-Huitle et al, 2004;Garcia-Segura and Brillas, 2011). However, based on the very low absolute rate constant for the reaction of OH with OA -1.4 Â 10 6 M À1 s À1 (Weiss et al, 2007;Ferro et al, 2010) e Guo et al (2016 considered that OA could be used as a direct oxidation probe. As regards to PHE and PCT, both DET and OH mediated oxidation can participate to the mineralization (rate constant of 1.4 Â 10 10 L mol À1 s À1 for oxidation of PCT by OH (Land and Ebert, 1967); rate constant of 9.8 Â 10 9 L mol À1 s À1 for oxidation of PHE by OH (Bisby and Tabassum, 1988)).…”

A comparison of electrochemical degradation of phenol on boron doped diamond and lead dioxide anodes

“…The BDD electrodes (supplied by CSEM, Neuchâtel) were made by chemical vapour deposition on a conductive substrate of polysilicium. Other details of the cell were given previously [20].…”

Electrochemical synthesis of peroxomonophosphate using boron-doped diamond anodes

“…In recent years, electrochemical oxidation with conductive-diamond anodes has become one of the most promising technologies in the treatment of industrial wastes polluted with organics [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] and in the electrosynthesis of inorganic oxidants [13,[33][34][35]. Compared with other electrode materials, conductive-diamond has shown higher chemical and electrochemical stability as well as a higher current efficiency.…”