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Frontiers of Environmental Science & Engineering >> 2021, Volume 15, Issue 4 doi: 10.1007/s11783-020-1352-8

Hexachlorobutadiene emissions from typical chemical plants

1. College of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710054, China
2. State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
3. School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310000, China

Available online: 2020-10-15

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Abstract

Abstract • Unintentional HCBD production in typical chemical plants was investigated. • The highest HCBD concentrations were found in the bottom residue. • Tri/tetrachloroethylene production processes were important HCBD sources. Hexachlorobutadiene (HCBD) was classed as a persistent organic pollutant under the Stockholm Convention in 2015. HCBD is mainly an unintentionally produced by-product of chlorinated hydrocarbon (e.g., trichloroethylene and tetrachloroethylene) synthesis. Few studies of HCBD formation during chemical production processes have been performed, so HCBD emissions from these potentially important sources are not understood. In this study, HCBD concentrations in raw materials, intermediate products, products, and bottom residues from chemical plants producing chlorobenzene, trichloroethylene, and tetrachloroethylene were determined. The results indicated that HCBD is unintentionally produced at much higher concentrations in trichloroethylene and tetrachloroethylene plants than chlorobenzene plants. The sum of the HCBD concentrations in the samples from all of the trichloroethylene and tetrachloroethylene production stages in plant PC was 247000 mg/mL, about three orders of magnitude higher than the concentrations in the tetrachloroethylene production samples (plant PB) and about six orders of magnitude higher than the concentrations in the chlorobenzene production samples (plant PA). The HCBD concentrations were highest in bottom residues from all of the plants. The concentrations in the bottom residue samples contributed 24%–99% of the total HCBD formed in the chemical production plants. The bottom residue, being hazardous waste, could be disposed of by incineration. The HCBD concentrations were much higher in intermediate products than raw materials, indicating that HCBD formed during production of the intended chemicals. The results indicate the concentrations of HCBD unintentionally produced in typical chemical plants and will be useful in developing protocols for controlling HCBD emissions to meet the Stockholm Convention requirements.

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