New insights in the dihydroxybenzenes-driven Fenton reaction: electrochemical study of interaction between dihydroxybenzenes and Fe(III).

It has been reported that the dihydroxybenzene (DHB) driven Fenton reaction is more efficient to degrade recalcitrant substrates than the simple Fenton reaction. The enhanced reactivity of the DHB driven Fenton reaction is not clear, but it could be explained by the formation of oxidant species different from the ones formed by classical Fenton reaction or by the shift of the redox potential of the complex formed by DHB and Fe(III). The redox reaction between Fe(III) and the DHBs 1,2-dihydroxybenzene (catechol, CAT), 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA), and 1,2-dihydroxy-3,5-benzenedisulfonate (TIRON) was studied by cyclic voltammetry to better understand the enhanced reactivity of the DHB driven Fenton reaction. It was determined that the amount of Fe(II) produced by the redox reaction between Fe(III) and DHBs was insufficient to explain the enhanced reactivity. Cyclic voltammograms (CV) of the DHBs/Fe(III) systems show a quasi-reversible or irreversible behavior and also shifting and splitting the anodic peaks. This effect can be related to DHBs oxidation by Fe(III), but not to a real interaction.