Two-electron transfer photoreduction of methyl viologen and perfluorooctanoic acid mediated by flavin mononucleotide at colloidal titanium dioxide interfaces

• Published in: New journal of chemistry 2023-12, Vol.47 (47), p.21661-21669
• Main Authors: Saeed, Tahseen S, Albalawi, Sarah S, Abuhagr, Abubkr, Althobaiti, Saja Abdulrahman, Hassanain, Hawazen M, Reeves, Donald M, Abdullah, Mohammed R, Sinn, Ekkehard
• Format: Article
• Language: English
• Subjects: Charge transfer; Density functional theory; Electron transfer; Electrons; Ethanol; Fluorine; Mathematical analysis; Molecular orbitals; Nanoparticles; Perfluoroalkyl & polyfluoroalkyl substances; Reduction; Titanium; Titanium dioxide
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d3nj04290a

Flavin mononucleotide (FMN) in methanol was photochemically reduced to FMNH 2 , which undergoes electron transfer with Methyl viologen (MV 2+ ) in ethanol. This charge transfer interaction results in the reduction of MV 2+ into MV + &z.rad;, as well as the storage of electrons. The spectroscopic experiments allow for the elucidation of quantitative electron transfer into MV 2+ . To study the redox potential for FMN species, the HOMO and LUMO energies were calculated using density functional theory (DFT) method on the B3LYP level with a basis set of 6-311G(d,p). The HOMO and LUMO energy calculations show that the redox state of FMNH 2 is energetically more favorable than FMNH&z.rad; for MV 2+ reduction. These studies revealed good agreement between the experimental results and computational predictions. Moreover, molecular electrostatic potential (MEP) was performed on the FMNH 2 -MV 2+ complex to determine the site of electron transfer, and the results were compared to the experimental results. FMN functionalized to the surface of colloidal titanium dioxide nanoparticles (TiO 2 NPs) showed enhanced reactivity toward the reduction of perfluorooctanoic acid (PFOA). The two-electron transfer reduction process is generated by irradiating FMN attached to TiO 2 , during which FMN reduces to FMNH 2 . The FMNH 2 then reacts with PFOA to produce shorter chain structures with fewer fluorine atoms, such as C 5 F 11 COOH. The results indicate that the rational organization of FMNH 2 /TiO 2 to mediate two-electron transfer is effective for the reductive degradation and remediation of PFOA. Environmentally friendly catalyst consisting of a flavin mononucleotide and titanium dioxide nanoparticles for MV 2+ and poly-fluorinated octanoic acid reduction.