Formation and Inventory of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans and Other Byproducts along Manufacturing Processes of Chlorobenzene and Chloroethylene

Abstract

Chlorinated organic chemicals are produced and used extensively worldwide, and their risks to the biology and environment are of increasing concern. However, chlorinated byproducts [e.g., polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)] formed during the commercial manufacturing processes and present in organochlorine products are rarely reported. The knowledge on the occurrences and fate of unintentional persistent organic chemicals in the manufacturing of organochlorine chemical is necessary for accurate assessment of the risks of commercial chemicals and their production. Here, PCDD/Fs were tracked throughout chlorobenzene and chloroethylene production processes (from raw materials to final products) by target analysis. Other byproducts that can further transform into PCDD/Fs were also identified by performing non-target screening. As a result, the PCDD/F concentrations were mostly the highest in bottom residues, and the octachlorinated congeners were dominant. Alkali/water washing stages may cause the formation of oxygen-containing byproducts including PCDD/Fs and acyl-containing compounds, so more attention should be paid to these stages. PCDD/Fs were of 0.17 and 0.21–1.2 ng/mL in monochlorobenzene and chloroethylene products, respectively. Annual PCDD/F emissions (17 g toxic equivalent in 2018) during chlorobenzene and chloroethylene production were estimated using PCDD/F emission factors. The results can contribute to the improvement of PCDD/F inventories for the analyzed commercial chemicals.

Target Analysis of Polychlorinated Naphthalenes and Nontarget Screening of Organic Chemicals in Bovine Milk, Infant Formula, and Adult Milk Powder by High-Resolution Mass Spectrometry

“…The nontarget analysis data indicated that benzene-ring-containing chemicals such as phenols and benzaldehyde were abundant in the samples. Such chemicals could act as precursors for the formation of PAHs, PCBs, PCNs, and Cl/Br-PAHs, which are toxic . It has been proposed that phenyl addition cyclization, in which phenyl radicals react to give PAHs, could occur and that naphthalene readily forms through such reactions .…”

“…Such chemicals could act as precursors for the formation of PAHs, PCBs, PCNs, and Cl/ Br-PAHs, which are toxic. 68 It has been proposed that phenyl addition cyclization, in which phenyl radicals react to give PAHs, could occur and that naphthalene readily forms through such reactions. 69 These results and the nontarget screening results indicated that benzene homologues and derivates made larger contributions to the chemicals in bovine milk than to the chemicals in infant formula and milk powder and that processing caused the number of polycyclic aromatic hydrocarbons to increase.…”

Integration of Nontarget Screening and QSPR Models to Identify Novel Organophosphate Esters of High Priority in Aquatic Environment

“…Similar to the BAF model in biofilm, log K ow also has the highest standardized coefficient (Table 2), while dipole moment (μ), which is commonly employed to describe the polarity of a molecule, 64 made a negative contribution to BMF. For those chemicals with increased μ, they are more readily dissolved in polar solvents like water, which prevents them from accumulating in organic phase.…”

Efficient Catalytic Elimination of Chlorobenzene Based on the Water Vapor-Promoting Effect within Mn-Based Catalysts: Activity Enhancement and Polychlorinated Byproduct Inhibition

“…Chlorinated volatile organic compounds (CVOCs), including dichloromethane, dichloroethane, trichloroethylene, and chlorobenzene (CB) etc., are a fairly intractable class of air pollutants. , Compared with other nonhalogenated VOCs, CVOCs have high toxicity, chemical stability, and strong dioxin relevance, which pose a serious threat to public safety and human health. − In addition, CVOCs emitted from coal-fired power plants, waste-to-energy plants, and other industrial sectors often coexist with other impurity components (typically water vapor), increasing the complexity of the treatment process. , Catalytic oxidation is widely recognized as the most promising technology for efficient purification of VOCs . As for CVOCs oxidation catalysts, in addition to catalytic activity, chlorine resistance and polychlorinated byproduct selectivity are also critical evaluation indicators. − These two properties determine the stability and environmental risk of the catalyst application.…”