We found that humin, insoluble in any pH conditions, assisted the microbial dehalogenation of pentachlorophenol and tetrabromobisphenol A, as well as the enhancement of the microbial iron reduction, as the solid-phase electron mediator. Humin had been neglected as the electrochemically-active material. However, the electrochemical function of humin was shown by the cyclic voltammogram. Chemically-reduced humin and the PCP-dechlorinating microbial enrichment made the PCP dechlorination, suggested the PCP-dechlorinating microorganisms received electron from humin for the dechlorination. The function was stable against the treatments with acids, alkaline, boiling, and chemical reduction but unstable against the treatment with hydrogen peroxide. This indicated that the organic fraction of humin as inorganic-organic complex was associated with the reaction center of humin as electron mediator. Analyses of solid-phase NMR (carbonyl carbon), FT-IR (carbonyl group and C=C double bond) and ESR (organic radical dependence on pH) suggested that quinone structure was contained in humin, probably as a functional group of electron mediation. These suggested that humin functioned as solid-phase electron mediator for the anaerobic respirations.

Soild-phase humin-assisted microbial dehalogenation of aromatic compounds under anaerobic conditions

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.