Controlling The Reactivity Of Chlorinated Ethylenes With Flavin Mononucleotide Hydroquinone

摘要

Reduction rate constants of the chlorinated ethylenes cis-1,2-dichloroethylene (cis-DCE), trichloroethylene (TCE), and tetrachloroethylene (PCE) reacted with flavin mononucleotide hydroquinone (FMNH_2) under anoxic conditions were investigated. FMNH_2 was produced in methanol solvent by the photoreduction of FMN. In aqueous solution, FMN was not fully reduced to FMNH_2 but instead yielded the semiquinone radical FMNH. However, when FMN was anchored to nanocrystalline TiO_2, band gap irradiation resulted in electron transfer from the TiO_2 conduction band to FMN, thus yielding FMNH_2. The FMNH_2 generated in aqueous solution on the TiO_2 surface was a stronger reductant toward chlorinated ethylenes, relative to FMNH_2 in solution. Furthermore, by combining the reactivity of the TiO_2 conduction band electrons [TiO_2(e-~(CB)] with FMNH_2, reduction rate constants for the chlorinated ethylenes increased by 2 orders of magnitude relative to FMNH_2 alone. The results show how biological molecules such as FMNH2 could have significant effects toward the remediation of organic pollutants.