Radical species formation during electrochemical treatment of organic pollutants in methanol: Effects of active and non-active anodes in chloride and sulfate media

Autor(es)

Santacruz, William ; Faria, Julia ; Nascimento, Otaciro R. ; Motheo, Artur J.

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ELECTROANALYTICAL CHEMISTRY; v. 979, p. 9-pg., 2025-02-15.

Resumo

Environmental preservation and sustainable resource management are crucial due to growing industrial production and rising pollution. Electrochemical processes show promise for treating water and degrading lowconcentration contaminants. However, these processes can be energy-intensive and require pre-concentration strategies. A cost-effective water treatment system using activated carbon adsorption and alcohol desorption enhances electrochemical degradation by producing a concentrated alcoholic solution, enabling more costefficient electrochemical degradation in practical applications. While hydroxyl radicals are well established as key oxidative species in electro-oxidation in aqueous media, research on oxidative species in methanol is still limited, and the degradation mechanism in this medium remains unexplored. This study aims to identify species formed during electro-oxidation in methanol using active (Ti/Ti0.7Ru0.3O2) and non-active boron-doped diamond (BDD) anodes. Radical species were detected through electron paramagnetic resonance spin trapping with 5,5-dimethyl-1-pyrroline N-oxide (DMPO). In chloride and sulfate media, methoxy and hydroxymethyl radicals were primarily generated from the solvent. Computational simulations (EasySpin and MathLab) confirmed these radicals with nitrogen and hydrogen hyperfine coupling constants of aN = 14-15 G and aH = 21-22 G for DMPOCH2OH and aN = 13-15 G and aH = 7-9 G for DMPO-OCH3. These values were lower than those previously reported, due to differences in solvent polarity. Chloride on the MMO anode promoted oxygen-centered radicals, while sulfate favored carbon-centered radicals. On the BDD anode, carbon-centered radicals were more prominent, though oxygen-centered ones also formed. This research underscores the crucial role of electrode composition and supporting electrolyte in determining the efficiency and degradation pathways during electrochemical oxidation. (AU)

• Processo FAPESP: 22/15337-0 - Comportamento de diferentes processos oxidativos avançados em meio alcoólico para a degradação de pesticidas
• Beneficiário: William Santacruz Parra
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 22/12895-1 - Processos avançados para a degradação de poluentes emergentes: materiais catalíticos, sensores eletroanalíticos e divulgação científica
• Beneficiário: Marcos Roberto de Vasconcelos Lanza
• Modalidade de apoio: Auxílio à Pesquisa - Temático