benzofurans and pentachlorobenzene

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), pentachlorobenzene (PeCBz) and hexachlorobenzene (HxCBz), which are listed in the Stockholm Convention, are commonly known as unintentionally produced persistent organic pollutants (UPOPs). As municipal waste incinerators (MWIs) have burgeoned in China, the emission of UPOPs is of great concerns. Compared to the extensive studies of PCDD/Fs emission, not much information of non-dioxin UPOPs (i.e., PCBs, HxCBz, and PeCBz) is available. In the present study, samples from raw gas (RG) after boiler, stack gas (SG) after air pollution control devices (APCDs) and fly ash (FA) samples were collected from typical MWIs in China. The analyses of SG samples indicate that PCDD/Fs are the major contributor to TEQ value, but non-dioxin UPOPs are the dominant compounds in terms of mass concentration. The mean emission factors of dl-PCBs, PeCBz, and HxCBz in SG are 0.372, 144, and 84.7 μg/t, respectively. In contrast with gaseous samples, FA contains higher mass concentration of PCDD/Fs and PCBs than that of PeCBz and HxCBz. In terms of homologues distribution of PCBs, di- to tetra-CBs were the predominant species in both SG and FA samples. PCB-126 is the major contributor to the TEQ concentration. The comparison of UPOPs composition in SG and RG samples shows that activated carbon adsorption process is capable of removing most PCDD/Fs, but less efficient for the removal of non-dioxin UPOPs.

Topics: Air Pollutants; Benzofurans; China; Chlorobenzenes; Coal Ash; Dibenzofurans, Polychlorinated; Environmental Monitoring; Environmental Restoration and Remediation; Gases; Hexachlorobenzene; Incineration; Industrial Waste; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins

We determined the distribution of polychlorinated biphenyls (PCBs), pentachlorobenzene (PeCBz), hexachlorobenzene (HxCBz), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in surface sediments at 21 sites inside and outside Muroran Port, Japan. The concentration ranges and geometric means of PCBs (Σ209PCB), PeCBz, HxCBz, and PCDD/Fs and toxicity equivalence quantity (total TEQ) of dioxins inside Muroran Port were 1,100-65,000 (mean, 17,000) pg/g dw, 37-220 (100) pg/g dw, 31-810 (84) pg/g dw, 69-410 (170) pg/g dw, and 0.51-6.2 (2.3) pg TEQ/g dw, respectively. Their corresponding inventories inside Muroran Port were estimated to be 76, 0.31, 0.32, 0.55, and 7.8 g TEQ, respectively. The amounts of these pollutants were higher inside the port than outside the port and especially large in the inner part of the port. Most PCBs were homologues and congeners of penta- to hepta-chlorinated compounds, and the PCBs around Muroran Port were derived from technical PCBs, especially KC500 and KC600. As for PCDD/Fs, the influence of pentachlorophenol was significant, although pollution due to chloronitrofen and combustion was detected. The congeners of PCDD/Fs predominantly contributed to total TEQ. The concentration distributions of PeCBz, HxCBz, and PCDD/Fs and total TEQ were highly correlated with one another. This indicates that they are derived from the same combustion process.

Topics: Benzofurans; Chlorobenzenes; Dioxins; Environmental Monitoring; Environmental Pollutants; Geologic Sediments; Hexachlorobenzene; Japan; Polychlorinated Biphenyls

Chlorobenzene (CBz) is the precursor of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) generated in the processes of waste incineration, and it is regarded as a good indicator of PCDD/Fs for realizing PCDD/Fs online monitoring, moreover, pentachlorobenzene (PeCBz) and Hexachlorobenzene (HxCBz) belong to Persistent Organic Pollutants (POPs). However, the emission control of CBz in waste incineration does not attract enough attention, so this study focused on the inhibition of the 3 CBz formation routes in waste combustion by ammonium sulfate and urea, including CB formation from fly ash, CB formation from 1,2-dichlorobenzene (1,2-DiCBz) and the combustion of model medical waste. The results showed that both ammonium sulfate and urea reduced CBz yield during these three thermal processes. For instance, the inhibition rates of tetrachlorobenzene (TeCBz), PeCBz and HxCBz were 66.8%, 57.4% and 50.4%, respectively, when 1% urea was co-combusted with medical waste. By comparing the effect of ammonium sulfate and urea on CBz formation by three routes, urea was considered as a comparatively stable inhibitor for CBz.

Topics: Ammonium Sulfate; Benzofurans; Chlorobenzenes; Coal Ash; Dioxins; Hexachlorobenzene; Incineration; Polymers; Urea

The concentrations and profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), pentachlorobenzene (PeCBz), hexachlorobenzene (HxCBz) and polychlorophenols in 2,4-D were investigated in this study. Two 2,4-D acid and three 2,4-D butyl ester enterprises were selected as typical 2,4-D producers. The total concentrations of 2,3,7,8-PCDD/Fs in the 2,4-D samples ranged from 355 to 35080ngkg(-1) and the corresponding TEQ values were in the range of 13.4 and 694.6ng WHO-TEQkg(-1). The concentrations of total PCBs in the 2,4-D were in the range of 16.1 and 8023ngkg(-1), and the WHO-TEQ values of the PCBs were between 0.057 and 108.3ng WHO-TEQkg(-1), while total PCBs were between 1486 and 47342ngkg(-1). The average emission factors were 414.4μg WHO-TEQt(-1) for PCDD/Fs and 21.9μg WHO-TEQt(-1) for PCBs. The polychlorobenzenes and polychlorophenols impurities may play a key role in the PCBs and PCDD/Fs formation. The impurities of PCDD/Fs and PCBs in 2,4-D may increase the risk for the human and environmental health.

Topics: 2,4-Dichlorophenoxyacetic Acid; Benzofurans; Chlorobenzenes; Chlorophenols; Dibenzofurans, Polychlorinated; Environmental Pollutants; Hexachlorobenzene; Humans; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins

The coking process has been found to be an important source of unintentionally produced persistent organic pollutants (UP-POPs). However, the concentrations, profiles, and emission factors of UP-POPs in fly ash from coke plants have not been studied. In this study, six UP-POPs (polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), hexachlorobenzene (HxCBz), and pentachlorobenzene (PeCBz)) were identified and quantified in fly ash from eight coke plants. The average concentrations of the PCDDs, PCDFs, and "dioxin-like" PCBs were 1.5, 2.26, and 0.26 pg TEQ g(-1), respectively, and the average concentrations of the PCNs, HxCBz, and PeCBz were 256, 290, and 146 pg g(-1), respectively. The proportion each homolog contributed to the total concentration of the PCDFs, PCBs, and PCNs decreased with increasing chlorination level. The PCDFs contributed the biggest proportion of the total UP-POPs toxic equivalents (TEQs), and the average emission factors in fly ash were 10.5, 17.3, and 1.82 ng TEQt(-1) for the PCDDs, PCDFs, and "dioxin-like" PCBs, respectively, and 1,792, 2,028, and 1,025 ngt(-1) for the PCNs, HxCBz, and PeCBz, respectively. These data are essential for establishing an integrated UP-POP release inventory.

Topics: Benzofurans; Chlorobenzenes; Coal Ash; Coke; Dibenzofurans, Polychlorinated; Environmental Monitoring; Environmental Pollutants; Hexachlorobenzene; Naphthalenes; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins

The production of chloranil is regarded as a potentially significant source of unintentional POPs. This research aimed to identify the contamination levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HxCBz), pentachlorobenzene (PeCBz) and polychlorophenols in chloranil samples and identify the formation pathways. The toxicity equivalent (TEQ) values for PCDD/Fs in the chloranil samples ranged from 163 to 1540200 pg I-TEQg(-1), while the PCB TEQ values ranged from 1.9 to 3.3 pg WHO-TEQg(-1). High levels of HxCBz, PeCBz and polychlorophenols were also detected in the chloranil samples. The average emission factors were 522.2 mg I-TEQt(-1) (PCDD/Fs), 0.0026 mg WHO-TEQt(-1) (PCBs), 32.6 mg t(-1) (HxCBz), and 136.6 mg t(-1) (PeCBz). The PCDD/Fs and PCBs are thought to be formed from the polychlorophenols and polychlorobenzenes generated during the chloranil production process. Purification of the chloranil products can reduce the unintentional POPs releases and protect the environment.

Topics: Benzofurans; Chemical Industry; China; Chloranil; Chlorobenzenes; Chlorophenols; Environmental Monitoring; Environmental Pollutants; Hexachlorobenzene; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins; Polymers

Six species of unintentionally produced persistent organic pollutions comprised of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, polychlorinated naphthalenes, hexachlorobenzene and pentachlorobenzene in soils collected from Shanxi province, China were determined. The sum toxic equivalent ranged from 0.14 to 2.20 with an average of 0.94 pg TEQ/g. Polychlorinated dibenzo-p-dioxins/furans contributed the most toxic proportion to the total toxic equivalent. CB-126 was the most toxic contributor to polychlorinated biphenyls. CN66/67 and CN73 are the dominant toxic congeners to polychlorinated naphthalenes. From the patterns, it was speculated that thermal related industries were possible sources of unintentionally produced persistent organic pollutions.

Topics: Benzofurans; China; Chlorobenzenes; Dibenzofurans, Polychlorinated; Environmental Monitoring; Environmental Pollution; Hexachlorobenzene; Naphthalenes; Organic Chemicals; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins; Soil Pollutants

Magnesium production is considered to be one potential source of unintentional persistent organic pollutants (unintentional POPs). However, studies on the emissions of unintentional POPs from magnesium metallurgy are still lacking. Emissions of unintentional POPs, such as polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), polychlorinated naphthalenes (PCNs), hexachlorobenzene (HxCBz) and pentachlorobenzene (PeCBz) are covered under the Stockholm Convention. In this study, these emissions were investigated through a magnesium smelting process. Stack gas and fly ash samples from a typical magnesium plant in China were collected and analyzed to estimate the emissions of unintentional POPs from magnesium metallurgy. Emissions factors of 412 ng TEQ t(-1) for PCDD/Fs, 18.6 ng TEQ t(-1) for dl-PCBs, 3329 μg t(-1) for PCNs, 820 μg t(-1) for HxCBz, and 1326 μg t(-1) for PeCBz were obtained in 2009. Annual emissions from magnesium metallurgy in China were estimated to be 0.46 g WHO-TEQ for PCDD/Fs and dl-PCBs, 1651 g for PCNs, 403 g for HxCBz and 653 g for PeCBz, respectively.

Topics: Air Pollutants; Benzofurans; China; Chlorobenzenes; Coal Ash; Dibenzofurans, Polychlorinated; Environmental Monitoring; Gases; Hexachlorobenzene; Magnesium; Metallurgy; Naphthalenes; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins

The formation processes of PCDD/Fs from pentachlorobenzene catalyzed by CuO under heating conditions were investigated. The results showed that, the amount of the formed PCDD/Fs increased with the temperature from 200 degrees C to 350 degrees C, and then decreased with futher increase of temperature from 350 degrees C to 450 degrees C. PCDD/Fs homologue pattern varied significantly according to the reaction temperature. At the lower temperature (200-250 degrees C), the major PCDD/Fs products were highly chlorinated ones; but at the higher temperature (400-450 degrees C), the low chlorinated PCDD/Fs predominated in the PCDD/Fs products. The change of temperature did not cause a systematical variation in the isomer distributions in each PCDD/Fs homologue. By comparing the formation of PCDD/Fs from pentachlorobenzene with the dechlorination of OCDD/F both under the catalysis of CuO at 400 degrees C, the precursor mechanism of PCDD/ Fs formation from pentachlorobenzene was speculated. Low chlorinated PCDDs mainly came from the dechlorination of highly chlorinated PCDDs which were formed from the pentachlorobenzene, whereas PCDFs could be mainly formed by the direct condensation of dechlorination products of pentachlorobenzene.

Topics: Benzofurans; Catalysis; Chlorobenzenes; Copper; Dibenzofurans, Polychlorinated; Hot Temperature; Polychlorinated Dibenzodioxins

The coking process is considered to be a potential source of unintentionally produced persistent organic pollutants (UP-POPs). However, intensive studies on the emission of UP-POPs from the coking industry are still very scarce. Emission of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), hexachlorobenzene (HxCBz), and pentachlorobenzene (PeCBz) covered under the Stockholm Convention were investigated for the coking process in this study. Stack gases from some typical coke plants in China were collected and analyzed to estimate the emission of UP-POPs from the coking industry. Emission factors of 28.9 ng WHO-TEQ tonne(-1) for PCDD/Fs, 1.7 ng WHO-TEQ tonne(-1) for dl-PCBs, 596 ng tonne(-1) for HxCBz, and 680 ng tonne(-1) for PeCBz were derived based on the investigated data. The annual emissions from the global coking industry were estimated to be 15.8 g WHO-TEQ for PCDD/Fs, 0.93 g WHO-TEQ for dl-PCBs, 333 g for HxCBz, and 379 g for PeCBz, respectively (reference year 2007). According to the distribution of PCDD/Fs, we argued for the de novo synthesis to be the major pathway of PCDD/F formation. With regard to the characteristics of dl-PCBs, the most abundant congener was CB-118, and the most dominant contributor to the total WHO-TEQ of dl-PCBs was CB-126.

Topics: Air Pollutants; Benzofurans; Chlorobenzenes; Coke; Dibenzofurans, Polychlorinated; Environmental Monitoring; Environmental Pollutants; Fungicides, Industrial; Hexachlorobenzene; Industrial Waste; Industry; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins