Investigation of persulfate production on BDD anode by understanding the impact of water concentration

Autor(es)

de Freitas Araujo, Karla Caroline ^[1] ; da Silva, Djalma Ribeiro ^[1] ; dos Santos, Elisama Vieira ^[1] ; Varela, Hamilton ^[2] ; Martinez-Huitle, Carlos A. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed Rio Grande do Norte, Inst Quim, Natal, RN - Brazil

^[2] Univ Sao Paulo, Inst Chem Sao Carlos, Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ELECTROANALYTICAL CHEMISTRY; v. 860, MAR 1 2020.
• Citações Web of Science: 0

Resumo

The formation of persulfate (S2O82-) in aqueous solution has been frequently considered as a direct oxidation of SO42- ions on boron-doped diamond (BDD) surface. Conversely, some authors have also suggested that slower reactions between center dot OH radicals and SO42- ions are feasible. However, no attempts have confirmed this electrochemical pathway because the studies have been frequently performed at diluted sulfuric acid solutions. Thus, the purpose of this work was to study the effect of the ratio H2O/H2SO4 on the electrochemical behavior at BDD surface in order to verify the possible participation of hydroxyl radical on the production of persulfate. Different electrochemical techniques (cyclic voltammetry, polarizations curves and impedance) were employed to understand the electrochemical behavior when different concentrations of H2O were added to concentrated H2SO4. Results clearly suggest that, intermediate species are necessary to promote the formation of S2O82-. The predominance of HSO4- ions at concentrated H2SO4 system with lowest water content (2%) suggests that sulfate radical specie (SO4-center dot) may be produced via the reaction of HSO(4)(-)( )with center dot OH radicals. Then, S2O82- production depends principally on the particular formation of center dot OH on BDD surface or BDD(SO4-center dot) sites rather than on the direct anodic oxidation of SO42- at BDD surface. These results are described and discussed in the light of current literature. (AU)

• Processo FAPESP: 13/16930-7 - Eletrocatálise V: processos eletrocatalíticos de interconversão entre as energias química e elétrica
• Beneficiário: Edson Antonio Ticianelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático