Electrochemical study of 2,3-dihydroxybenzoic acid and its interaction with Cu(II) and H202 in aqueous solutions: Implications for wood decay (1)
Publication Name: Environmental Science and Technology
Publication URL: https://pubs.acs.org/doi/10.1021/es049714q
The electrochemical behavior of 2,3-dihydroxybenzoic acid (2,3-DHBA) and the electron-transfer characteristics between Cu(II) and 2,3-DHBA were studied in aqueous solutions using cyclic voltammetry (CV). The overall electrochemical oxidation process of 2,3-DHBA by Cu(II) may be classified as a chemical reaction involving one-electron oxidation of 2,3-DHBA to its semiquinone radical in solution, followed by an electron-transfer reaction involving the oxidation of the semiquinone radical to a quinone at the electrode surface. In the presence of H2O2, oxidation of 2,3-DHBA by Cu(II) is enhanced due to the regeneration of Cu(II) by H2O2 oxidizing Cu(I). The redox cycling between Cu(I)/Cu(II) and H2O2 also produces hydroxyl radicals (OH¥). Even though the presence of OH¥ may not be detected at the surface of a glassy carbon electrode, production of electroactive dissolved oxygen (O2) suggests the presence of OH¥. The production of O2 is dependent on Cu(II):H2O2 concentration ratio. At the electrode surface and when the initial Cu(II):H2O2 is less than 1, O2 is produced, suggesting that H2O2 may act as a scavenger for OH¥; at initial Cu(II):H2O2 > 1, the production of O2 is not favored, and OH¥ will be involved in the oxidation of Cu(I) and the organic ligand. The reaction mechanisms proposed in this study indicate that OH¥ production by chelator-mediated Fenton reactions is favorable under conditions found in the wood cell wall.