Electrochemical oxidation of dibenzothiophene compounds on BDD electrode in acetonitrile–water medium

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 847; p. 113172
• Main Authors: Ornelas Dávila, O., Lacalle Bergeron, L., Ruiz Gutiérrez, P., Dávila Jiménez, M.M., Sirés, I., Brillas, E., Roig Navarro, A.F., Beltrán Arandes, J., Sancho Llopis, J.V.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.08.2019; Elsevier Science Ltd
• Subjects: Acetonitrile; Anodes; Anodizing; BDD; Chromatography; Dessulfuració; Desulfurization; Dibenzothiophene; Dibenzothiophenes; Electrochemical desulfurization; Electrochemical oxidation; Electrolysis; Electrolytic oxidation; Fourier transforms; Gas chromatography; High performance liquid chromatography; Hydroxyl radicals; Infrared analysis; Ions; Mass spectrometry; Oxidació electroquímica; Oxidation; Quadrupoles; Scientific imaging; Sulfone; Sulfones; Sulfoxide; Voltammetry; Water discharge; Dibenzothiophenes; Sulfoxide; Electrochemical desulfurization; BDD; Sulfone
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2019.05.054

The electrochemical oxidation of dibenzothiophene and two derivatives, namely 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene, was investigated either separately or as a mixture, on a BDD anode in a miscible acetonitrile (87.5% v/v)–water (12.5% v/v, 0.01M NaNO3) solution. Linear sweep voltammetry, cyclic voltammetry, chronoamperometry and bulk electrolysis under potentiostatic conditions suggested the probable occurrence of two pathways: direct electrochemical oxidation and indirect reaction with hydroxyl radicals and other reactive oxygen species formed at the BDD anode surface during water discharge. The products extracted upon electrolysis at 1.5 and 2.0V vs. SCE were analyzed by Fourier-transform infrared spectroscopy, gas chromatography–mass spectrometry and ultra-high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS). The main molecules identified were the corresponding sulfoxides or sulfones, depending on the applied anodic potential. Possible oxidation routes for the dibenzothiophene compounds are proposed. [Display omitted] •Electrochemical oxidation of dibenzothiophenes in CH3CN/H2O using a BDD anode•Oxidation is direct or mediated by reactive oxygen species like OH.•Selective oxidation of single compounds or mixtures to sulfoxides or sulfones•The conversion depends on concentration, applied potential and water content.•The electrochemical reactivity on BDD decreases as: 4,6-DMDBT≥4-MDBT>DBT.