Formation of PCDD/Fs and PCBs in the process of production of 1,4-dichlorobenzene

Abstract

The occurrence and distribution of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in a typical process of production of 1,4-dichlorobenzene (p-DCB) were investigated systematically in this study. P 5 CDFs and H 6 CDFs were the main congeners of PCDD/Fs, while only low levels of other PCDD/Fs were detected in the samples. The concentrations of PCBs were up to 4614 ng/g in the semi-manufactured products, and 1797 ng/g in the product p-DCB. It was also found that high chlorinated PCB congeners increased with the further chlorination. The levels of PCDD/Fs decreased obviously in the purification process, while PCBs could not be removed effectively. Polychlorophenols and other important dioxin precursors (1,4-dichloro-2-phenoxybenzene and 2-phenyl-2 0 ,5,5 0 -trichlorophenol) were also analyzed. Polychlorophenols which ortho-and parapositions of the hydroxyl were substituted by chlorine were the main congeners. In addition, a possible pathway of the formation of PCDD/Fs and PCBs in the production of p-DCB was presented. The results of this article suggest that re-estimation on the risk of using p-DCB products, especially the products for daily use such as mothballs, is expected.

Unintentional formed PCDDs, PCDFs, and DL-PCBs as impurities in Chinese pentachloronitrobenzene products

“…Due to the challenging matrix of pure organochlorine compounds (i.e., the pesticide active ingredient), the isotope dilution technology using high resolution gas chromatography/ high resolution mass spectrometer (HRGC/HRMS) has been utilized for an accurate congener-specific analysis in other studies assessing PCDD/Fs in organochlorine compounds (Holt et al 2010;Liu et al 2004;Masunaga et al 2001).…”

Formation and contamination of PCDD/Fs, PCBs, PeCBz, HxCBz and polychlorophenols in the production of 2,4-D products

“…According to several reports in the literature (Weber and Hagenmaier, 1999a;Liu et al, 2004;Horii et al, 2008;Altarawneh et al, 2009;Kishi et al, 2010), polychlorophenols serve as the important precursors in the formation of PCDD/Fs. The concentrations of the polychlorophenols in the 2,4-D product samples are shown in Fig.…”

“…In addition, the concentrations of PCBs, PeCBz and HxCBz in all samples share the similar trends, indicating a close relationship between PCBs concentrations and polychlorobenzenes concentrations in 2,4-D production. Polychlorobenzenes, the important precursor of PCBs and PCDD/Fs (Liu et al, 2004), may be condensed and reacted with polychlorophenols to form PCBs and PCDD/Fs during the 2,4-D production process at the right temperature. Thus, the purification process for the dioxin precursors such as polychlorophenols and polychlorobenzenes plays a pivotal role in controlling the formation and release of PCBs and PCDD/Fs during 2,4-D production process, and therefore protecting the human and environmental health.…”

The release of persistent organic pollutants from a closed system dicofol production process

“…C 6 H 5 Cl and Cl 2 are used as raw materials, so the C 6 H 5 Cl that had not already reacted with CCl 3 CHO could react with Cl 2 to produce polychlorobenzenes (Liu et al, 2004). In a similar way to the formation of PCDD/Fs during p-dichlorobenzene production, chlorinated PCDD/Fs will be formed from the polychlorobenzenes during the dicofol production process.…”

“…The production of polychlorophenols, polychlorobenzenes, chloranil, and organochlorine pesticides are important sources of PCDD/Fs in China (Liu et al, 2004;Zheng et al, 2008;Liu et al, 2012;Liu et al, 2013). Chlorine is a key ingredient in the production of dicofol, so dicofol production may lead to the formation of PCDD/Fs.…”