ELECTROCHEMICAL INCINERATION OF SHORT-CHAIN CARBOXYLIC ACIDS WITH NB‑SUPPORTED BORON DOPED DIAMOND ANODE: SUPPORTING ELECTROLYTE EFFECT INTO THE ELECTROGENERATED OXIDANT SPECIES (HYDROXYL RADICALS, HYDROGEN PEROXIDE AND PERSULFATE)

Abstract

This work describes the electrochemical oxidation study of three short chain carboxylic acids (acetic, oxalic and formic 0.18 mol L-1) using different electrolysis conditions (electrolyte composition and current density) in an electrochemical reactor fitted with niobiumsupported/BDD electrode (Nb/BBD) as anode and titanium plate as cathode. The experiments were focused to elucidate if the oxidation of these carboxylic acids involved a direct or a mediated oxidation pathway, as well as their electrochemical incineration efficiency using this electrochemical reactor. The amount of oxidizing species (hydroxyl radicals, hydrogen peroxide, and persulfate) produced at Nb/BDD electrode was spectroscopically determined. The electrochemical kinetics study in H2SO4 and HClO4 solutions, as well as the chemical oxygen demand and total organic carbon analysis for each one of the carboxylic acids studied in both media, gave us information to propose a degradation mechanism for the electrochemical degradation of the carboxylic acids in each electrolytic media. The degradation in H2SO4 is promoted by the persulfate production, whereas in HClO4 by •OH.

Keywords

• carboxylic acids
• electrooxidation
• boron doped diamond
• supporting electrolyte
• oxidants