benzofurans and 2-chlorodibenzo-4-dioxin

Chlorination and thermal degradation of 2-chlorodibenzodioxin and dibenzofuran were investigated using sealed tubes at 350 degrees C in the presence of CuCl(2) or CuCl. Twelve organic species, including polychlorobenzenes, were identified and quantified as a function of residence time. Time behaviours of PCDDs and PCDFs regarding destruction processes were compared. The formation of polychlorobenzenes from the thermal heterogeneous degradation of PCDDs was only a minor pathway but it could contribute to the good linear correlation observed between the concentration of polychlorobenzenes and those of PCDD/Fs in the emissions of municipal solid waste incinerators.

Topics: Benzofurans; Carbon Dioxide; Chlorobenzenes; Copper; Dibenzofurans, Polychlorinated; Dioxins; Halogenation; Hot Temperature; Polychlorinated Dibenzodioxins

Strain YA was newly isolated from an enrichment culture of river sediment and was identified as Janibacter sp. It was able to utilize dibenzofuran as the sole source of carbon and energy. Strain YA degraded > 90% of 1-chloro-dibenzo-p-dioxin (1-CDD) and > 80% of 2-chloro-dibenzo-p-dioxin in 18 hours with each initial concentration at 40 mg/L. A novel metabolite, 2-chloro-2',6-dihydroxydiphenylether, was observed in 1-CDD degradation. From the metabolites detected by gas chromatography-mass spectrometry, strain YA was supposed to have at least two types of oxidation pathways in 1-CDD degradation.

Topics: Actinomycetales; Benzofurans; Biodegradation, Environmental; Dioxins; DNA, Bacterial; DNA, Ribosomal; Gas Chromatography-Mass Spectrometry; Geologic Sediments; Molecular Sequence Data; Molecular Structure; Rivers; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Water Microbiology

Removal of dibenzofuran, dibenzo-p-dioxin, and 2-chlorodibenzo-p-dioxin (2-CDD) (10 ppm each) from soil microcosms to final concentrations in the parts-per-billion range was affected by the addition of Sphingomonas sp. strain RW1. Rates and extents of removal were influenced by the density of RW1 organisms. For 2-CDD, the rate of removal was dependent on the content of soil organic matter (SOM), with half-life values ranging from 5.8 h (0% SOM) to 26.3 h (5.5% SOM).

Topics: Benzofurans; Biodegradation, Environmental; Dioxins; Ecosystem; Kinetics; Pseudomonas; Soil Microbiology; Soil Pollutants