Use of olive oil for soil extraction and ultraviolet degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans.
This paper represents a successful laboratory-scale photolysis of soil-bound tetra- to octachlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in olive oil. The irradiation source consisted of two blacklight lamps emitting light at a near-ultraviolet range. Samples used in the experiments included pure 1,2,3,4,6,7,8-heptachlorodibenzofuran, PCDD/F extract made of a wood preservative (chlorophenol product Ky 5), and soil that was highly contaminated with PCDD/Fs. Degradation of 1,2,3,4,6,7,8-heptachlorodibenzofuran dissolved in olive oil proceeded rapidlywith a first-order reaction half-life of 13 min. Irradiation of a soil sample resulted in an 84% reduction in PCDD/F toxicity equivalent (I-TEQ) in 17.5 h. A more complete degradation of soil-bound PCDD/Fs was achieved after extraction of the soil with olive oil. The oil was effective in solubilizing PCDD/Fs. After one extraction at room temperature, only 9% of I-TEQ remained in soil. Irradiation of the resulting extract reduced toxicity of the extract by 99%, and even the highly chlorinated congeners octachlorodibenzo-p-dioxin and octachlorodibenzofuran degraded easily (97 and 99% degradation, respectively). Photodegradation byproducts found included diphenyl ether and small amounts of dechlorination products, which were mainly nontoxic PCDD/Fs. Degradation was probably mediated by light absorption of unsaturated fatty acids and phenolic compounds in olive oil, leading to sensitized photolysis of PCDD/Fs.
Isosaari
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P
Division of Environmental Health, National Public Health Institute, Kuopio, Finland. pirjo.isosaari@ktl.fi
Tuhkanen
T
T
Vartiainen
T
T
D001572:Benzofurans / Q000032:analysis / Q000737:chemistry*; D004147:Dioxins / Q000032:analysis / Q000737:chemistry*; D005227:Fatty Acids; D000069463:Olive Oil; D010782:Photolysis; D010938:Plant Oils; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D014466:Ultraviolet Rays
D001572:Benzofurans; D004147:Dioxins; D005227:Fatty Acids; D000069463:Olive Oil; D010938:Plant Oils; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants