Thermally induced formation of polychlorinated dibenzofurans from Aroclor 1254-contaminated mineral oil

Environmental Health Perspectives
R S NarangA S Narang

Abstract

Numerous laboratory simulations and real-world events have demonstrated the thermal conversion of neat or high concentration of PCBs into the much more toxic PCDFs. Since millions of mineral oil transformers currently in service contain PCB concentrations in the 50 to 5000 ppm range, the thermal behavior of dilute PCB solutions is of practical and regulatory significance. In this work, neat Aroclor 1254 and 5000 ppm Aroclor 1254 in mineral oil were subjected to pyrolysis and combustion under a range of experimental conditions to define parameters resulting in maximal PCDF yields. The dependence of PCDF yield on Aroclor 1254 concentrations was then investigated in the 5000 to 50 ppm range. Combustion experiments demonstrated that PCDF yields expressed as micrograms PCDF/gram PCB were independent of concentration range, confirming that the process is kinetically first order in PCB. Much lower yields of PCDF were observed in the open tube pyrolysis experiments, as compared to combustion experiments and to earlier and concurrent sealed tube experiments. Slightly improved yields were observed in the pyrolysis experiments at lower concentrations, suggesting the existence of a PCB or PCDF destruction process of higher than first order...Continue Reading

References

Jun 1, 1978·Bulletin of Environmental Contamination and Toxicology·M MoritaC Rappe
Jan 1, 1976·Bulletin of Environmental Contamination and Toxicology·J NagayamaY Masuda
May 1, 1985·Environmental Health Perspectives·J PaasivirtaL Virkki

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Citations

Sep 14, 2001·Journal of Advanced Nursing·M TakaseL Burt

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