Identification of the Released and Transformed Products during the

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Energy and the Environment

Identification of the released and transformed products during the thermal decomposition of a highly chlorinated paraffin shanzhi xin, Wei Gao, Yawei Wang, and Guibin Jiang Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b01729 • Publication Date (Web): 03 Aug 2018 Downloaded from http://pubs.acs.org on August 7, 2018

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Environmental Science & Technology

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Identification of the released and transformed products during the thermal

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decomposition of a highly chlorinated paraffin

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Shanzhi Xin1,2, Wei Gao1,4, Yawei Wang1, 3, 4,*, and Guibin Jiang1

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1

5

Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China

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2

7

Wuhan 430056, China

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3

Institute of Environment and Health, Jianghan University, Wuhan 430056, China

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4

University of Chinese Academy of Sciences, Beijing 100049, China

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for

Hubei Key Laboratory of Industrial Fume and Dust Pollution Control, Jianghan University,

10 11

*Corresponding author

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Dr. Yawei Wang

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State Key Laboratory of Environmental Chemistry and Ecotoxicology

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Research Center for Eco-Environmental Sciences

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Chinese Academy of Sciences

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P.O. Box 2871, Beijing 100085, China

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Tel: +8610-6284-9124

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Fax: +8610-6284-9339

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E-mail: [email protected]

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ABSTRACT

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As plasticizers and flame retardants, highly chlorinated paraffin (CP70) and related

25

products will experience thermal processes during their lifecycle stages. However, the thermal

26

transformation data for CP70 is limited. In this study, we investigated the release and

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transformation of chlorinated and unchlorinated products during the thermal decomposition of

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CP70. Large quantities of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs)

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and unsaturated analogues (Cl-polyenes or chlorinated olefins) as well as toxic chlorinated

30

aromatic hydrocarbons were formed synergistically under different thermal conditions. The

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yield of SCCPs increased gradually in the gas phase, while it decreased in the residue at

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200-400°C. SCCPs can be transformed further and generated mostly polychlorinated

33

biphenyls (PCBs). Oxygen promoted the thermal transformation of SCCPs and MCCPs and

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decreased the yield in the gas phase at >400-500°C. In contrast, the yield of both SCCPs and

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MCCPs increased notably under N2 at 800°C. Chlorobenzene (CBz), PCBs and

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polychlorinated naphthalenes (PCNs) were the main chlorinated aromatic hydrocarbons and

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obtained a maximum yield at 500-600°C. The present findings indicate that CP70-containing

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materials may synergistically generate SCCPs, MCCPs and other toxic chlorinated

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compounds during their life cycles.

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Abstract Art

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Introduction

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Chlorinated paraffins (CPs) are complex mixtures comprising thousands of isomers and

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congeners. Of all the congeners of CPs, short-chain chlorinated paraffins (SCCPs) have

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attracted much attention due to their similar properties compared to persistent organic

48

pollutants (POPs)1-3. In May 2017, the eighth Conference of Parties of the Stockholm

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Convention decided to list SCCPs in Annex A of the Stockholm Convention as a group of new

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POPs4. Although SCCPs have been found in various environmental matrices, human food and

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organs5-11, the sources of SCCPs in the environment are still not fully investigated.

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It is estimated that the consumption of CPs in 1935-2015 reached 11.2 million tons12, and

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the average consumption of CPs for plasticizers (PVC) is 312,900 tons in 2011-201413.

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Currently, the production of CPs is over 1 million tons per year5. China is the largest producer

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of CPs, in which three major products are produced, i.e., CP42 and CP52 (~42% and ~52%

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chlorine, mainly short- to medium-chain CP) and CP70 (~70% chlorine, mainly long-chain

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CP, LCCPs)14. CPs have been detected in the commercial products15. Previous studies found

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that the mass fraction of SCCPs in CP42, CP52 and CP70 was in the range of 0.06-11.0%,

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0.04-31.9% and 0.07-27.6%, respectively16, 17. Currently, CP70 and MCCPs are produced as

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the alternative for SCCPs and CP70-based materials are high production volume products in

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EU and USA18. It is foreseeable that the production and application of CP70 will increase in

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the future.

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CP70 commonly functions as a flame retardant in plastics and other polymers19. CP70

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and related products will experience thermal processes during their entire lifecycle stages, 4 ACS Paragon Plus Environment

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such as open burning or waste incineration. The thermal processing and recycling of CPs

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containing material (PVC) will cause the release of SCCPs into the atmosphere20. Our

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previous study indicated that SCCPs and MCCPs can be formed from the thermal

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decomposition of CP52 and released into the gas phase at 200-400°C. Meanwhile, toxic

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chlorinated

70

transformation of CP70 and the release of SCCPs, MCCPs and other persistent toxic

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substances need to be further investigated.

aromatic

hydrocarbons

were

formed

synergistically21.

Likewise,

the

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Up to now, some studies have been conducted to investigate the decomposition of high

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chlorinated CPs. However, only a few were able to characterize the degradation products.

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Camino et al. found that dehydrochlorination occurred at 250°C for CPs with 70% chlorine,

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and 60-70% of total chlorine was released22. Bergman et al. analyzed the degradation products

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of CPs with 59% and 70% chlorine. It was found that the highly chlorinated paraffins and the

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commercial CPs generated polychlorinated benzenes, toluenes, biphenyls and naphthalenes23.

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Other study revealed that CPs can be transformed into chlorinated olefins (COs) through the

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elimination of hydrochloric acid on hot metal surfaces during metal drilling works24.

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Information regarding the formation of SCCPs when CP70 was subject to heat is still

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unknown. The lack of such data limits the establishment of a thorough SCCPs emissions

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inventory and an evaluation of the environmental risk of CPs.

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In this study, the thermal decomposition of CP70 was simulated in a lab-scale furnace.

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The object was to investigate the possible decomposition characteristics of CP70 and, more

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importantly, to explore the release and transformation of SCCPs, MCCPs and other toxic

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compounds, as well as the emission levels. The results of the present study are helpful to 5 ACS Paragon Plus Environment


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understand the synergistic emissions of CPs and other toxic pollutants when CP70 or related

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products experience thermal processes during their whole life cycle.

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Materials and Methods

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Materials and reagents

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In this study, commercial CP70 (chlorine content 70±2%) was the feedstock and was

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collected from a CP manufacturing facility in Fujian province, China. Generally, the formula

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of CP70 was C25H30Cl22 or C24H29Cl21, the average molecular weight and the carbon chain is

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in the range of 1060-1100 and C22-C28, respectively18, 25, 26. The raw CP70 is in the form of

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white powder. First, the contents of SCCPs, MCCPs and the chlorinated and nonchlorinated

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aromatic hydrocarbons in the feedstock were analyzed, and it was found that they were lower

97

than under limit of detection in CP70. The ash composition of CP70 was analyzed by X-ray

98

fluorescence (XRF, Rigaku Primus

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Supporting Information (SI). It was found that the inorganic species in CP70 consisted mostly

100

of inert Si and Mg (~86% of total inorganic species detected). The reagents in this study were

101

pesticide grade and the same as in our previous studies21, 27.

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Experimental setup and procedures

, Japan), and the result is given in Figure S1 in the

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The thermal decomposition of CP70 was investigated by a thermogravimetric analyzer

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and a lab-scale furnace. The experiment procedures can be found in our previous study21. For

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the thermogravimetric analysis, the heating program was from room temperature to 800°C

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with the heating rate of 2, 5, 10, 20, 50, 100°C/min. ~10 mg of the feedstock was used for

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each heating rate. The schematic diagram of the experimental combustion system is shown in 6 ACS Paragon Plus Environment

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Figure S2. The temperature was preset at 200, 300, 400, 500, 600 and 800°C under N2 and air

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with a flow rate of 150 mL/min. For each trial, a 300±5 mg sample was placed in the sample

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basket with a thin layer and put into the center of the reactor. The volatile matter was cooled

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down and absorbed by the downstream absorption liquid. To ensure the complete

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decomposition of the feedstock, the reaction time for each trial was 30 mins.

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Quantitation and quantification of products

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After the experiment, the products in the quartz reactor and glass tube and those in

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absorption liquid are collectively called the volatile fraction (VF). The VF was concentrated

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on a rotary evaporator to ~2 mL. The solid char or ash residue after the experiment was called

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residue fraction (RF). The RF was extracted by a mixture of dichloromethane and hexane

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under microwave and then filtered. Prior to analysis, each sample was spiked with 10 ng of a

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1,5,5,6,6,10-hexachlorodecane (13C10) 100 µg/mL solution in cyclohexane (Cambridge

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Isotope Laboratories, Andover, USA) as the internal standard. The SCCPs, MCCPs and other

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chlorinated products were analyzed by using an Agilent 7200 GC-QTOF mass spectrometer

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(GC-qTOF-HRMS, Agilent Technologies, USA) with chemical ionization and electron

123

ionization source. The instrument was operated at 5 spectra/s (m/z 50-600), and the mass

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resolution was approximately 15,000 at m/z 300-600. The chlorinated aromatic products were

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analyzed semi-quantified by the external standard method. The standard solution and the

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detailed analysis program of GC-qTOF-HRMS can be found in text S1 in the SI and our

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previous works21, 27. The accurate masses of the 96 quantitative and qualitative ions of SCCPs

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and MCCPs were given in Table S1. The surface functionality of the residue was analyzed by 7 ACS Paragon Plus Environment


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FTIR spectroscopy (VERTEX 70 Bruker, Germany). The testing procedures were presented in

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text S2.

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Quality assurance and quality control

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After each experiment, the quartz reactor, sample basket, glass tube and absorption bottle

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were rinsed three times with dichloromethane and hexane mixtures. To minimize

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contamination, the quartz reactor and sample basket were calcinated at 800°C under air for 1

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h. The glass tube and other glassware were triple rinsed with n-hexane and baked in an oven

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at 450°C for 12 h before usage. The repeatability of the experiment was assessed by

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performing three runs. The relative standard deviations (RSDs) for SCCPs and MCCPs were

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in the range of 4.6-8.0% and 6.4-10.1%, respectively, while that for CBz, PCBs and PCNs

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ranged from 5.0%-8.4%. Experimental blanks were conducted under the same conditions

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without loading CP70, while procedural blanks were performed for each batch of solvents.

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SCCPs and MCCPs were not detected in these blank tests. The amount of CBz, PCBs and

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PCNs determined in blank tests was in the range of 0.83-5.7 µg/g, which account for less than

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1.5% of the total amount detected. This indicates that the experimental and analytical

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procedures have an acceptable level of reproducibility. The limit of detection (LOD) of the

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instrument was determined by the standard deviation of the signal intensity of the five

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replicate injections multiplied by Student’s T-value at a 95% confidence level. The LOD for

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the SCCPs and MCCPs was defined as detection of the corresponding most abundant

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congener group, i.e. C11H18Cl6 for SCCPs and C14H23Cl7 for MCCPs in this study. Details

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regarding the LOD of the instrument can be found in our previous works27. The LOD of the 8 ACS Paragon Plus Environment

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MCCPs was 30 ng/mL, while that of the SCCPs was 25 ng/mL. A blank test was conducted

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before the experiment and after every three samples.

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Results and Discussion

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Thermal decomposition behaviors of CP70

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The TG and DTG plots of CP70 decomposition at a heating rate of 10°C/min are shown

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in Figure S3(a). The thermal decomposition of CP70 was divided into two stages. The first

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stage is located in the range 250-397°C with weight loss of 64.6%, which is consistent with

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previous study22. The weight loss is ascribed to the release of volatile fractions (VF),

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including condensable and non-condensable compounds. The maximum mass loss rate was

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both attained at ~344°C, indicating that the gas environment exerts a minor effect on the

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volatilization of CP70. This is supported by the results that the yields of the RF and volatile

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fraction (VF) were very close at 200-400°C (Figure S4). Previous studies found that

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dehydrochlorination was the initial reaction when chlorinated compounds were degraded22,

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28-30

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temperature than the gas environment. In the second stage (397-800°C), substantial

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differences were observed from the decomposition of CP70. The weight loss of the residue

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was only 10.8% under N2 due to the continuous carbonization of char. However, in the air

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condition, the combustion of residue char gave rise to a weight loss of approximately 30%,

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and the char was burned out as temperature exceeded 545°C.

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Formation of SCCPs and MCCPs

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. This finding suggests that dehydrochlorination of CP70 was more sensitive to

The total ion chromatogram (TIC) and the corresponding extracted ion chromatography 9 ACS Paragon Plus Environment


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(EIC) extraction for SCCPs and MCCPs in the VF under N2 is shown in Figure 1. The zero

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abundance of the total ion chromatogram (TIC) of CP70 confirmed that there are no

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detectable SCCPs and MCCPs in the feedstock. Since CPs are produced by the chlorination of

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n-alkanes, homologues with more chlorine than carbon atoms (overchlorinated congeners)

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may exist in the starting material. However, due to technical and standard limitations, these

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congeners could not be analyzed. The thermal decomposition of CP70 and the

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dehydrohalogenation of overchlorinated CP in the starting material can result in the formation

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of SCCPs, MCCPs and lower-chlorinated unsaturated homologues (chlorinated alkenes,

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Cl-alkene). Since the saturated CPs are highly interfered by the chlorinated alkenes31, the

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detectable CPs in the RF and VF should be a mixture of SCCPs/MCCPs and Cl-alkene. The

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peak area of TIC increases with temperature (Figure 1), indicating that the amount of mixture

182

increased. With temperature increasing, the peak area of the EIC increases remarkably and

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changes coincidentally with that of the TIC compared to that of CP70. The peak area of the

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TIC and EIC increases significantly at 800°C, revealing the high concentrations of mixture of

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SCCPs/MCCPs and Cl-alkene in the VF.


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-CI TIC Scan

CP70

(a)

-CI EIC 430.8628 +/- 50ppm

(b)

-CI EIC 472.9098 +/- 50ppm

-CI TIC Scan

-CI EIC 430.8628 +/- 50ppm

-CI EIC 472.9098 +/- 50ppm

-CI TIC Scan

-CI EIC 430.8628 +/- 50ppm

-CI EIC 472.9098 +/- 50ppm

-CI TIC Scan

-CI EIC 430.8628 +/- 50ppm

-CI EIC 472.9098 +/- 50ppm

-CI TIC Scan

-CI EIC 430.8628 +/- 50ppm

-CI EIC 472.9098 +/- 50ppm

-CI TIC Scan

-CI EIC 430.8628 +/- 50ppm

-CI EIC 472.9098 +/- 50ppm

-CI TIC Scan

-CI EIC 430.8628 +/- 50ppm

-CI EIC 472.9098 +/- 50ppm

(c)

200oC

300oC

400oC

500oC

600oC

800oC

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8 9 10 11 12 13 14 15 16 17 18 19 Counts vs. Acquisition Time (min)

11 12 13 14 15 16 17 18 19 Counts vs. Acquisition Time (min)

11 12 13 14 15 16 17 18 19 Counts vs. Acquisition Time (min)

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Figure 1 The (a) TIC of raw CP70 feedstock and the corresponding EIC of (b) SCCPs (C11Cl9

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for representation) (c) MCCPs (C14Cl9 for representation) at mass tolerances of 50 ppm at

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different temperatures under N2. The detailed target analyte CP (SCCPs and MCCPs) groups

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and their accurate mass of quantitative and qualitative [M-Cl]- ions was given in Table S1.

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The peak areas of all the measured CP congener groups at different experiment conditions are

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shown in Table S3-S4.

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The mass yield of SCCPs and MCCPs from the thermal decomposition of CP70 is shown

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in Figure 2. The determined amount of CPs (SCCPs, MCCPs) and the corresponding

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percentage of compounds in relation to CP70 is given in Table S5. As shown in Figure 2a,

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SCCPs were not detected in the VF at 200°C. However, in the RF, SCCPs were quantified

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with a yield of 0.032% (320 µg/g CP70) under N2 and 0.067% (617 µg/g CP70) under air. 11 ACS Paragon Plus Environment


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From the FT-IR results, the peak intensity of the residue obtained at 200°C was only slightly

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lower than that of the raw feedstock (Figure S5), indicating that the structure of CP70 largely

200

remained intact. With temperature increasing, the yield of the SCCPs in the VF increased

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remarkably, which is approximately twice that in the RF. Moreover, more SCCPs were

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generated under the N2 condition either in the VF and RF (Figure 2a) because oxygen

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accelerates the pyrolysis rate and thus may facilitate the decomposition of SCCPs32. This is

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consistent with the results in which the peak intensity of the residue obtained at 300°C under

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air decreased more pronouncedly than that under N2 (Figure S5 a-b). The peak at 1706 cm-1

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was assigned to the stretching of the C=C double bond, while that at 677 cm-1 was attributed

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to the stretching of the C-Cl bond33. This finding demonstrated that CP70 decomposed

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remarkably in the presence of oxygen and formed a charred solid residue with double bonds

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at 300°C. In the RF, negligible amount of SCCPs (~10 µg/g) were formed at 400°C, whereas

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that in the VF increased significantly from 0.1% (1000 µg/g CP70) at 300°C to 0.42% (4200

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µg/g CP70) at 400°C.

20000

VF-N2

RF-N2

VF-air

RF-air

SCCPs (a)

1600 1200

15000 10000

RF

800 VF 400

5000

25000

2000

Mass yield [µg/g]

Mass yield [µg/g]

25000

20000

VF-N2

RF-N2 MCCPs (b) RF-air

VF-air

VF

15000

2000 1600 1200

10000

800

5000

400 RF

0

212

0 200 300 400 500 600 700 800 o

0 200 300 400 500 600 700 800

Temperature [ C]

0

o

Temperature [ C]

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Figure 2. The mass yield of SCCPs (a) and MCCPs (b) during thermal decomposition of

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CP70 under N2 and air. RF: residue fraction; VF: volatile fraction.

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In the second stage, SCCPs were almost undetectable in the RF at 500°C and above. 12 ACS Paragon Plus Environment

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However, in the VF, SCCPs reached the maximum yield at 400°C under air and then

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decreased constantly. In contrast, the yield of SCCPs increased as the temperature increased

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under N2. This demonstrated that oxygen has a strong capacity to promote the decomposition

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of SCCPs. In other words, combustion with sufficient oxygen can reduce the formation of

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SCCPs. However, oxygen is insufficient for most combustion processes since the combustible

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materials are usually polymers with high carbon and hydrogen contents. For example, open

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burning deteriorates the oxygen transport issues and causes oxygen-limited combustion

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conditions34.

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It should be noted that CP70 thermal decomposition released 0.2% SCCPs (2000 µg/g

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CP70) at 600°C. Nevertheless, due to the low thermal stability, SCCPs were not detected from

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the decomposition of CP52 at 600°C21. Meanwhile, with higher gas flow rates, higher yields

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of SCCPs were obtained (Figure S6a). This result means that the decomposition of SCCPs

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occurred at a lower extent at high gas flow rates. This indicated that SCCPs can be regarded

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as a reactant and prone to decompose further. The above results suggested that the symmetry

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cleavage of the carbon chain of CP70 produces more SCCPs since the chain length of CP70 is

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generally 22-25 carbon atoms25. More importantly, the formation rate of SCCPs was greater

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than the decomposition rate. The yield of SCCPs increased substantially to 0.99% (9905 µg/g

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CP70) at 800°C under N2, while it was still as high as 0.16% (1618 µg/g CP70) under air.

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Although the thermal stability of SCCPs is low, the thermal decomposition of CP70 can also

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release considerable amounts of SCCPs even at high temperatures. This indicated that the

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combustion of CP70-related products has a high risk of the formation and release SCCPs into

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the environment. Thus, it can be speculated that accidental fires, construction debris fires, 13 ACS Paragon Plus Environment


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copper wire reclamation, electronics waste, fireworks, household waste, structural fires, tire

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fires, etc. are all potential sources of SCCPs emission34.

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The formation of MCCPs with temperature is similar to that of SCCPs, suggesting that

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both were formed simultaneously (Figure 2b). In the RF, the yield of MCCPs decreases

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constantly, and they are not detected at 600°C and above. Meanwhile, the yield of MCCPs in

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the residue was lower than that of SCCPs, implying that the symmetry cleavage pattern of

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CP70 is more pronounced in the residue. In the VF, the yield of MCCPs increases

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continuously under N2 as well, and the maximum yield of 1.67% (16694 µg/g CP70) was

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obtained at 500°C and begins to decrease in the presence of oxygen. The amount of MCCPs

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was approximately 2-fold higher than that of SCCPs as temperature exceeded 400°C.

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Meanwhile, the yield of MCCPs decreases as the gas flow rate was increased to 1000 mL/min

249

(Figure S6b), suggesting that MCCPs are more likely to be a product rather than a reactant.

250

Theoretically, the asymmetric or random cleavage of the carbon chain of CP70 produces

251

MCCPs together with small molecular fragments. This revealed that the asymmetric pattern is

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more dominant than the symmetrical pattern at high temperatures. Thermal decomposition of

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CP70 released as much as 1.93% MCCPs (19333 µg/g CP70) under N2 and 1.3% MCCPs

254

(12977 µg/g CP70) under air at 800°C, posing a high potential environmental risk, since

255

MCCPs may have similar nocuous characteristics to SCCPs35. Furthermore, more MCCPs

256

were generated under N2 than air, showing that oxygen also promoted the decomposition of

257

MCCPs.

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The relative abundance of carbon and chlorine atom congeners of SCCPs and MCCPs in

259

the VF and RF are given in Figures S7-S8. As seen, C10 and C11 congeners were the dominant 14 ACS Paragon Plus Environment

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carbon homologs for SCCPs in the VF at 300°C. The fraction of the C10-11 decreased with

261

temperature, while the C12-13 congeners increased continuously (Figure S7 a-b), suggesting

262

that shorter chain portions of SCCPs were prone to decompose further. In the RF, C10 and C13

263

congeners decreased constantly, while C11 congeners increased with the temperature increases

264

at 200-600°C (Figure S7 e-f). MCCPs can be detected at 200°C under N2 in the VF, but they

265

were composed mostly of C14 congeners. However, in the RF, the relative content of low

266

carbon congeners of MCCPs was higher than the high carbon congeners. At 300°C, a

267

considerable number of C15-17 congeners were identified in the VF. With increasing

268

temperature, C14 congeners decreased constantly, while C15 congeners increased slightly. In

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the RF, low carbon congeners (C14-16) decreased with the increase in temperature at

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200-600°C (Figure S8 e-f).

271

With respect to chlorine atom homologs, high-chlorine congeners, such as Cl8-10, were

272

the dominant congeners of SCCPs both in the VF and RF. For low-chlorine species (Cl5-7),

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each congener account for less than 10% of the total content. The fraction of high chlorine

274

congener (Cl8-10) decreases with temperature, while Cl5-7 congeners show the opposite trend,

275

confirming the dehydrochlorination of SCCPs. In the RF, the decrease of Cl8-10 congeners was

276

significant in the presence of oxygen, proving that oxygen facilitate the dechlorination of

277

CP70. MCCPs were mainly composed of Cl6-8 congeners under N2 at 200°C in the VF, while

278

high chlorine congeners (Cl8-10) was the dominants in the RF. The fraction of low-chlorine

279

congeners (Cl5-7) decreased, whereas high-chlorine congeners (Cl8-10) increased with

280

temperature (Figure S8-c, d, g, h). This might be due to the release and dechlorination of

281

overchlorinated CPs in the feedstock. It should be noted that fewer low-chlorine congeners 15 ACS Paragon Plus Environment


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(Cl5-6) were obtained under N2, while more high-chlorine congeners (Cl9-10) were obtained in

283

the presence of oxygen, especially at high temperatures. This confirmed that the

284

dehydrochlorination of MCCPs is favored by oxygen and temperature.

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Formation of chlorinated aromatic hydrocarbons

286

Aliphatic hydrocarbons (AHC), aromatic compounds (Ar) and their chlorinated

287

derivatives (Ar-Cl) were the main detectable compounds in the VF. The compositions of these

288

compounds at different temperatures are shown in Figure 3(a). It is interesting that AHC and

289

Ar were the predominant compounds at 200°C. They might be formed initially in the RF and

290

released into the gas phase since SCCPs and MCCPs mainly remained in the residues (Figure

291

2). At 300°C and above, AHC and Ar were almost undetectable, and Ar-Cl became dominant.

292

The formation of Ar-Cl during thermal process have received more attention since they are

293

more toxic than aromatic compounds and are closely related to the formation of dioxins.

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In the VF, Ar-Cl consisted of CBz, PCBs, PCNs and aliphatic substituted Ar-Cl (S-Ar-Cl).

295

The distribution of these compounds is given in Figure 3(b). As seen, PCBs occupy the largest

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proportions both under N2 and air conditions at 300°C and resulted in the abundant formation

297

of ≥2-ring aromatics, which accounts for approximately 90% of the total compounds detected.

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The 1-ring aromatic hydrocarbons are comprised mostly of CBz and its aliphatic substituted

299

derivatives. It can be concluded that PCBs were formed via the condensation of dechlorinated

300

SCCPs rather than aromatic ring growth reactions. Moreover, the formation of PCBs is prior

301

to PCNs and CBz. Other studies of oxidation of chlorinated aromatics has found that SiO2

302

was a mildly active condensation and weak chlorinating/dechlorinating catalyst36. That is 16 ACS Paragon Plus Environment

Page 16 of 33

Page 17 of 33


probably why a large amount of ≥2-ring aromatics were generated in the VF. As the

304

temperature increases from 300-500°C, the fraction of PCBs decreased continuously, whereas

305

that of CBz, PCNs and S-Ar-Cl increased steadily. 90

100 90 80

AHC Ar Ar-Cl (a)

45 30

N2 air

15 0 200

300

400

500

600

700

800

Fraction of total chlorinated species[%]

Fraction of total compounds [%]

303

N2 air

75

(b)

60 45 30 15 0 200

o

Temperature [ C]

306

CBz PCBs PCNs S-Ar-Cl

300

400

500

600

700

800

o

Temperature [ C]

307

Figure 3. (a) the AHC, Ar and Ar-Cl as a percentage of the total compounds detected and (b)

308

the CBz, PCBs, PCNs and S-Ar-Cl as a percentage of the total chlorinated species in the VF

309

under N2 and air at different temperatures

310

Formation of CBz

311

Figure 4 shows the mass yield and homolog distributions of CBz in the VF. Increasing

312

temperature caused a continuous increase in the yield of CBz, and it reached the maximum

313

yield at 600°C. The thermal decomposition of CP70 gave as much as 0.39% CBz (3903 µg/g

314

CP70) under air and 0.16% CBz (1574 µg/g CP70) under N2. After that, the yield of CBz

315

decreased. It should be noted that the amount of CBz from CP70 decomposition was

316

approximately 2- to 5-fold higher than that from CP5221. Generally, more radicals and small

317

molecules are produced from the decomposition of higher chlorinated hydrocarbons and

318

participated in the aromatization reactions37. Furthermore, the gas environment exerts a strong

319

influence on the formation of CBz as well, e.g., oxygen promoted the formation of CBz. This

320

is because oxygen not only increases the pyrolysis rate, but it can also oxidize HCl into Cl 17 ACS Paragon Plus Environment


321

radicals via the Deacon process, and chlorination occurs as combustion proceeds38. Hence,

322

chlorination may be enhanced in the presence of oxygen and result in a higher yield of CBz.

323

The formation of CBz is related to the decomposition of SCCPs and MCCPs. From

324

Figure 4, it can be seen that the yield of CBz and MCCPs increased synchronously at

325

400-600°C, whereas that of SCCPs tended to decrease (Figure 2). It can be speculated that

326

CBz can be formed either from the condensation of unsaturated structures from the

327

decomposition of SCCPs or the aromatization of fragments, which is accompanied by the

328

formation of MCCPs. Moreover, the oxidative condensation of small molecular fragments

329

contributed largely to the formation of CBz. In other words, the former route is favored in the

330

presence of oxygen, and the latter route is predominated when oxygen is insufficient or in

331

oxygen-free conditions.

332

The most abundant congeners of CBz were mono-, di- and tri-CBz, which accounted for

333

more than 95% of the total CBz. Among these congeners, di-CBz was dominant, followed by

334

mono- and tri-CBz. Meanwhile, the yield of these congeners under air was also much higher

335

than that under N2. Furthermore, PeCBz and HxCBz were detected with a low concentration

336

of 0.2-6 µg/g in the presence of oxygen. Generally, previous studies found that the high

337

chlorinated benzenes can generate PCDD/Fs during municipal waste incineration39, 40. Hence,

338

oxygen is favorable for the formation of toxic chlorinated aromatic hydrocarbons but poses

339

adverse effects to the environment.


Page 18 of 33


5000

monoditritetrapentasum

4000 3000 2000

Mass concentration [µg/g]


Page 19 of 33

(a)

1000 0 100 200 300 400 500 600 700 800

340

5000

monoditritetrapentahexasum

4000 3000 2000

(b)

1000 0 100 200 300 400 500 600 700 800

o

Temperature [ C]

o

Temperature [ C]

341

Figure 4. The total mass concentration and homolog compositions of CBz in the VF under (a)

342

N2 and (b) air at different temperatures

343

Formation of PCBs

344

The formation of PCBs in the VF under N2 and air at different temperatures is shown in

345

Figure 5. It can be seen that the concentrations of PCBs increased with temperature and got

346

the maximum yield at 600°C. It is generally assumed that PCBs are thermally decomposable41.

347

Yasuhara et al. found that the amount of PCBs was proportional to the chlorine content of the

348

feedstock at temperature lower than 700°C. However, small amount of PCBs were formed as

349

the temperature exceeds 800°C42. Studies found that PCBs start to decompose at temperature

350

higher than 800°C and thus the high temperature incinerator was generally used to thermal

351

destruction of PCB wastes43. In China, the incineration temperature of real-life waste

352

incinerator should be exceeded 850°C44.

353

The maximum yield of PCBs was determined to be 0.34% (3386 µg/g CP70) for N2 and

354

0.32% (3191 µg/g CP70) for air, whereas the formation of PCBs from polyvinyl chloride

355

(PVC) incineration was in the range of 15.0 ng/g to 77.6 ng/g45. This is mainly due to the

356

lower concentrations of CPs in the matrix polymers. Wang et al. found that PVC cable sheath

357

contains 191 mg/g SCCPs and 145mg/g MCCPs, accounting less than 20% of the total 19 ACS Paragon Plus Environment


358

weight15. In the municipal waste incinerator, the total PCBs concentration was 0.5-35 µg/kg in

359

the filter fly ash46. However, PCBs were not detected in the RF in the present study,

360

suggesting that the release of PCBs was influenced by the matrix polymers.

361

The gas environment shows a minor effect on the formation of PCBs compared to CBz,

362

especially at 200-400°C (Figure 5a). However, the increased number of PCBs at low

363

temperatures (200-400°C) was significantly higher than that of CBz. The yield of PCBs at

364

300°C was 28- to 36-fold higher than that of CBz, resulting in the high proportion of PCBs in

365

the VF (Figure 3b). Meanwhile, the fraction of CBz increased continuously with temperature.

366

This suggested that PCBs were likely to be formed through the self-combination of

367

chlorinated polyene resulting from the dehydrochlorinated SCCPs or MCCPs. The formation

368

of PCBs is preferable to other Ar-Cl since the fraction of C12 is lower than C10 and C11

369

congeners at low temperature ranges (Figure S7). The direct combination of aromatic rings,

370

such as phenyl radicals or phenyl with benzene, was shown to be the dominant pathways for

371

biphenyl formation47, 48. It suggested that the 1-ring aromatics, which probably includes CBz,

372

may contribute the formation of PCBs.

373

With respect to the distribution of congeners of PCBs, the di- and tri-PCBs were found to

374

be the most abundant congeners either in N2 or air atmospheres (Figure 5c-d), which

375

contribute to more than 70% of the total PCBs detected. The second-most abundant congeners

376

were mono- and tetra-CBz species, accounting for approximately 24%. Among all the PCBs

377

congeners, 12 congeners have attracted much attention for their dioxin-like toxicity, and they

378

are collectively called dioxin-like PCBs (dl-PCBs). The toxic equivalent quantity (TEQ)

379

concentration of dl-PCBs equals to the sum of the concentrations of individual congeners 20 ACS Paragon Plus Environment

Page 20 of 33

Page 21 of 33


multiplied by the respective toxicity equivalency factors (TEF) for human and mammals,

381

which is recommended by the World Health Organization49. The mass concentration of

382

Σdl-PCBs and the WHO-TEQ concentrations are shown in Figure 5b. The distributions of

383

dl-PCBs are given in Figure S9. N2 air

4000

(a) 3000 2000 1000 0

400

dl-PCB N2

300

air

TEQ

600 ∑dl-PCB

100

200 300 400 500 600 700 800

TriHexa-

(c)

1500 1000 500 0

o

2000 1500

o

MonoTetra-

DiPenta-

TriHexa-

(d)

1000 500 0

200 300 400 500 600 700 800

200 300 400 500 600 700 800 o

Temperature [ C]

385

0

Temperature [ C]



DiPenta-

400 200

0

o

MonoTetra-

800

200

200 300 400 500 600 700 800

2000

1000

(b)

Temperature [ C]

384

1200

TEQ

Mass concentration [ng/g]

Mass yield [µg/g]

5000


380

Temperature [ C]

386

Figure 5. The total mass yield of PCBs (a), concentration of Σdl-PCBs and WHO-TEQ (b) in

387

the VF and the distribution of homolog profiles of PCBs under N2 (c) and air (d) at different

388

temperatures

389

The mass concentration of Σdl-PCB and the WHO-TEQ changes synchronously and

390

exhibit similar trends as the temperature. The maximum concentration of Σdl-PCB was 186

391

µg/g at 500°C, accounting for ~5.8% of the total PCBs. Sakai et al. detected total amount of

392

dl-PCBs in the gas and residue from waste incineration was 0.2-6.0 ng/Nm3 and 0.06-2.1 ng/g,

393

respectively41. The WHO-TEQ concentration was three orders of magnitude lower than that 21 ACS Paragon Plus Environment


394

of Σdl-PCB. The maximum TEQ concentration was 862 ng/g. It should be noted that higher

395

concentrations of Σdl-PCB and WHO-TEQ were obtained in an oxidative atmosphere at

396

temperatures lower than 600°C, possibly due to the drastic decomposition of CPs.

397

Concerning the distributions of WHO-TEQ, PCB-77 was the predominant congener. The

398

maximum concentration of PCB-77 was 116 µg/g at 600°C under N2 and 123 µg/g under air

399

at 500°C, contributing ~66% of the Σdl-PCB (Figure S9). The second-most abundant

400

congener was PCB-81, with a maximum concentration of 27.3-28.1 µg/g, representing

401

15-18% of the Σdl-PCB. The concentrations of the rest of the dl-PCB congeners were lower

402

than 10 µg/g, and they occupied less than 5% of the Σdl-PCB. The above results indicated that

403

temperature rather than the gas atmosphere was the key factor that affects the formation of

404

dl-PCBs. In other words, when CP70 or related products were exposed to heat, they generated

405

toxic POPs regardless of the surrounding atmospheres.

406

Formation of PCNs

407

Figure 6 illustrates the total yield of PCNs and the corresponding homolog distributions

408

in the VF. It can be seen that the formation of PCNs was similar to that of PCBs, i.e., it

409

increased first and then decreased with temperature. The highest yield of PCNs from CP70

410

decomposition was 0.19% (1929 µg/g CP70) under N2 at 600°C and 0.18% (1844 µg/g CP70)

411

under air at 500°C. For the homolog distribution, low chlorinated congeners were dominant,

412

such as mono-, di- and tri-PCNs. These congeners accounted for over 90% of the total PCNs

413

quantified. Likewise, temperature appears to be the most influential factor affecting the

414

formation of PCNs. The yield of PCNs was nearly half that of PCBs, since PCBs were formed

415

more preferentially than PCNs. 22 ACS Paragon Plus Environment

Page 22 of 33

Page 23 of 33


MonoDiTriTetraPentaSum

2000 1500 1000



2500

(a)

500 0 200 300 400 500 600 700 800 900

416

o

2500

MonoDiTriTetraPentaHexaSum

2000 1500 1000

(b)

500 0

200 300 400 500 600 700 800 900 o

Temperature [ C]

Temperature [ C]

417

Figure 6. The total mass yield and the homolog distribution of PCNs in the VF under (a) N2

418

and (b) air at different temperatures

419

It is widely recognized that naphthalene was formed mostly by the propargyl addition to

420

benzyl and the hydrogen abstraction/acetylene addition (HACA) mechanism48. The

421

chlorination of naphthalene as well as the HACA mechanism will result in the formation of

422

PCNs50. As mentioned above, as a higher chlorinated hydrocarbon, the thermal decomposition

423

of CP70 produces more radicals and small molecules to participate in molecular growth

424

reactions. The most abundant inorganic species in the feedstock is Si, which is a weak

425

chlorination/dechlorination and mildly active condensation catalyst36. Meanwhile, the gas

426

environment had no major influence on the yields of PCNs. Therefore, it can be seen that the

427

condensation of chlorinated fragments from CP70 rather than naphthalene chlorination might

428

be the main routes for the formation of PCNs.

429

As the temperature exceeds 500°C, the yield of CBz, PCBs and PCNs began to decrease.

430

At the same time, the 3-ring chlorinated aromatic hydrocarbons were formed (Table S6), such

431

as 1-chloro-anthracene, 1,5-dichloro-anthracene, 9-(dichloromethylene)-9H-fluorene, and

432

2,5-dichloro-1,1':2',1''-terphenyl. These compounds were identified by the deconvolution of

433

the GC chromatogram, as shown in Figure S10. This result indicated that the 2-ring aromatics, 23 ACS Paragon Plus Environment


434

mainly PCBs and PCNs, underwent ring-growth reactions.

s

l ca tri e m ym

435 436

Figure 7. The possible transformation pathways of CP70. The solid lines indicate the

437

favorable routes, while the dash lines mean the possible reaction routes during the thermal

438

decomposition of CP70.

439

The possible thermal decomposition pathways of CP70 decomposition are shown in

440

Figure 7. CP70 undergoes symmetrical and asymmetric chain cleavage initially, which leads

441

to the formation of SCCPs and MCCPs, together with significant amount of chlorinated and

442

nonchlorinated unsaturated molecular fragments. Meanwhile, these two carbon chain cleavage

443

patterns occurred competitively, and it seems that an asymmetric pattern is more favorable.

444

SCCPs are prone to decompose further via dehydrochlorination and subsequent cyclization or

445

aromatization, which mostly formed PCBs at 200-400°C. In contrast, fewer MCCPs are

446

decomposed. Nevertheless, CBz and PCNs are generated among the small fragments that

447

resulted from the formation of MCCPs. Moreover, the radical additions of CBz contribute to


Page 24 of 33

Page 25 of 33


448

the formation of PCNs. At high temperatures (>500°C), the asymmetric chain cleavage

449

becomes the predominant reaction and produces more small molecules or radicals, which in

450

turn, accelerate the addition of chlorinated aromatic hydrocarbons to generate large

451

molecules.

452

Environmental Implications

453

With the increasing restriction and regulation of SCCPs, the production and consumption

454

of CP70-based materials is expected to increase in the future. CP70 and related products are

455

likely to be processed by thermal processes during their entire lifecycle stages, including fire

456

and waste incineration, etc. However, according to the present work, the thermal

457

decomposition of CP70 can lead to the synergistic emission of SCCPs, MCCPs, respective

458

unsaturated analogues and chlorinated aromatic hydrocarbons (PCBs, PCNs, etc.), which have

459

been included in the Stockholm Convention. It indicates that the fate of CP70-based materials

460

deserves more attention, which means we should improve more confident instrumental

461

method to identify the longer carbon chain chlorinated paraffins, evaluate the environmental

462

transport and transformation of these un-fully recognized CP group congeners.

463

Our study revealed that temperature and the gas environment are both the key parameters

464

affecting the release of SCCPs and other pollutants. We found that higher temperature and

465

sufficient oxygen can minimized the release of SCCPs. However, SCCPs and other pollutants

466

are released mainly in the form of gaseous rather than solid, suggesting that they can release

467

into the atmosphere as long as they are formed during thermal processes. Therefore,

468

regulatory actions or emission reduction technology may be needed to control the potential 25 ACS Paragon Plus Environment


469

emissions of SCCPs during waste incineration.

470

Nevertheless, it should be realized that products from different manufactory contain

471

variant amount of CP70 and the incineration of pure CP70 is definitely different with that of

472

real-life CP70-based products. The matrix, metal catalyst, and other additives may influence

473

the decomposition of CP70 greatly, and thus the actual emission of CPs in waste incineration

474

were more complicated than the present study. In this regard, further work should be carried

475

out on the emission of CPs during the thermal treatment of CPs-containing products/wastes.

476

ASSOCIATED CONTENT

477

Supporting Information

478

Additional detailed information is available free of charge via the Internet at

479

http://pubs.acs.org. Supporting Information includes the analyse and test methods,

480

information of the target CP (SCCPs and MCCPs) groups and their peak area (Table S1, S3,

481

S4), the extracted chlorinated aromatic hydrocarbons (Table S2), the amount of CPs and

482

chlorinated aromatic hydrocarbons (Table S5), the content of Ar-Cl (Table S6), the ash

483

composition of CP70 (Figure S1), the experimental system (Figure S2), The TG and DTG

484

curves of CP70 (Figure S3), the mass yield of residue fraction (RF) and volatile fraction (VF)

485

(Figure S4), the FT-IR spectra of CP70 and the solid residue (Figure S5), the mass yield of

486

SCCPs and MCCPs under different gas flow rate (Figure S6), the relative abundance of

487

carbon and chlorine atom congeners of SCCPs and MCCPs (Figure S7, S8), the distribution

488

of homolog profiles of dl-PCB (Figure S9), the chromatogram and mass spectra of the major

489

≥3- ring Ar-Cl (Figure S10).

490

AUTHOR INFORMATION 26 ACS Paragon Plus Environment

Page 26 of 33

Page 27 of 33


491

Corresponding Author

492

∗

493

Notes

494

The authors declare no competing financial interest.

495

ACKNOWLEDGMENT

496

We thank the National Natural Science Foundation of China (21625702, 21337002,

497

21777183), the National Basic Research Program of China (2015CB453102), the Strategic

498

Priority Research Program of the Chinese Academy of Sciences (XDB14010400), and

499

Sanming Project of Medicine in Shenzhen (SZSM201811070) for financial support.

500

REFERENCES

501

1. Ma, X. D.; Zhang, H. J.; Wang, Z.; Yao, Z. W.; Chen, J. W.; Chen, J. P., Bioaccumulation

502

and Trophic Transfer of Short Chain Chlorinated Paraffins in a Marine Food Web from

503

Liaodong Bay, North China. Environ. Sci. Technol. 2014,48(10), 5964-5971.

504

2. Strid, A.; Bruhn, C.; Sverko, E.; Svavarsson, J.; Tomy, G.; Bergman, A., Brominated and

505

chlorinated flame retardants in liver of Greenland shark (Somniosus microcephalus).

506

Chemosphere 2013,91(2), 222-228.

507

3. Feo, M. L.; Eljarrat, E.; Barceló, D., Occurrence, fate and analysis of polychlorinated

508

n-alkanes in the environment. TrAC Trends in Analytical Chemistry 2009,28(6), 778-791.

509

4. POPRC. Recommendation by the Persistent Organic Pollutants Review Committee to list

510

short-chain chlorinated paraffins in Annex A to the Convention (UNEP/POPS/COP.8/14).

511

http://chm.pops.int/TheConvention/ConferenceoftheParties/Meetings/COP8/tabid/5309/Defau

E-mail: [email protected]



512

lt.aspx

513

5. Zeng, L.; Lam, J. C. W.; Wang, Y.; Jiang, G.; Lam, P. K. S., Temporal Trends and Pattern

514

Changes of Short- and Medium-Chain Chlorinated Paraffins in Marine Mammals from the

515

South China Sea over the Past Decade. Environ. Sci. Technol. 2015,49(19), 11348-11355.

516

6. Diefenbacher, P. S.; Bogdal, C.; Gerecke, A. C.; Glüge, J.; Schmid, P.; Scheringer, M.;

517

Hungerbühler, K., Short-Chain Chlorinated Paraffins in Zurich, Switzerland—Atmospheric

518

Concentrations and Emissions. Environ. Sci. Technol. 2015,49(16), 9778-9786.

519

7. Hilger, B.; Fromme, H.; Volkel, W.; Coelhan, M., Occurrence of chlorinated paraffins in

520

house dust samples from Bavaria, Germany. Environ. Pollut. 2013,175,16-21.

521

8. van Mourik, L. M.; Gaus, C.; Leonards, P. E. G.; de Boer, J., Chlorinated paraffins in the

522

environment: A review on their production, fate, levels and trends between 2010 and 2015.

523

Chemosphere 2016,155,415-428.

524

9. Xia, D.; Gao, L.; Zheng, M.; Li, J.; Zhang, L.; Wu, Y.; Tian, Q.; Huang, H.; Qiao, L.,

525

Human Exposure to Short- and Medium-Chain Chlorinated Paraffins via Mothers’ Milk in

526

Chinese Urban Population. Environ. Sci. Technol. 2016,51(1), 608-615.

527

10. Cao, Y.; Harada, K. H.; Liu, W.; Yan, J.; Zhao, C.; Niisoe, T.; Adachi, A.; Fujii, Y.; Nouda,

528

C.; Takasuga, T.; Koizumi, A., Short-chain chlorinated paraffins in cooking oil and related

529

products from China. Chemosphere 2015,138(1), 104-111.

530

11. Wang, Y.; Gao, W.; Wang, Y.; Jiang, G., Distribution and Pattern Profiles of Chlorinated

531

Paraffins in Human Placenta of Henan Province, China. Environ. Sci. Technol. Lett. 2017,5(1),

532

9-13.

533

12. Glüge, J.; Wang, Z.; Bogdal, C.; Scheringer, M.; Hungerbühler, K., Global production, 28 ACS Paragon Plus Environment

Page 28 of 33

Page 29 of 33


534

use, and emission volumes of short-chain chlorinated paraffins – A minimum scenario. Sci.

535

Total Environ. 2016,573(1132-1146.

536

13. Zhang, B.; Zhao, B.; Xu, C.; Zhang, J., Emission inventory and provincial distribution of

537

short-chain chlorinated paraffins in China. Sci. Total Environ. 2017,581, 582-588.

538

14. TANG En- tao; qin, Y. L.-. Industry status of chlorinated paraffin and its development

539

trends (in Chinese). China Chlor-Alkali 2005,2(3), 1-3.

540

15. Wang, C.; Gao, W.; Liang, Y.; Wang, Y.; Jiang, G., Concentrations and congener profiles

541

of chlorinated paraffins in domestic polymeric products in China. Environ. Pollut.

542

2018,238,326-335.

543

16. Gao, Y.; Zhang, H.; Su, F.; Tian, Y.; Chen, J., Environmental Occurrence and Distribution

544

of Short Chain Chlorinated Paraffins in Sediments and Soils from the Liaohe River Basin, P.

545

R. China. Environ. Sci. Technol. 2012,46(7), 3771-3778.

546

17. Li, T.; Gao, S.; Ben, Y.; Zhang, H.; Kang, Q.; Wan, Y., Screening of Chlorinated Paraffins

547

and Unsaturated Analogues in Commercial Mixtures: Confirmation of Their Occurrences in

548

the Atmosphere. Environ. Sci. Technol. 2018,52(4), 1862-1870.

549

18. Environmental Risk Evaluation Report: Long chain chlorinated paraffins (LCCPs);

550

978-1-84432-977-9; United Kingdom Government Environment Agency: Bristol, BS32 4UD,

551

2009; https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment

552

_data/file/290855/scho0109bpgr-e-e.pdf

553

19. Sun, Y.; Wang, X.; Li, J.; Yu, J., The status and development prospect of chlorinated

554

paraffins (In Chinese). Chlor-Alkali Industry 2005,6(6), 26-29.

555

20. Zhan, F.; Zhang, H.; Wang, J.; Xu, J.; Yuan, H.; Gao, Y.; Su, F.; Chen, J., Release and 29 ACS Paragon Plus Environment


556

Gas-Particle Partitioning Behaviors of Short-Chain Chlorinated Paraffins (SCCPs) During the

557

Thermal Treatment of Polyvinyl Chloride Flooring. Environ. Sci. Technol. 2017,51(16),

558

9005-9012.

559

21. Xin, S.; Gao, W.; Wang, Y.; Jiang, G., Thermochemical emission and transformation of

560

chlorinated paraffins in inert and oxidative atmospheres. Chemosphere 2017,185,899-906.

561

22. Camino, G.; Costa, L., Thermal degradation of a highly chlorinated paraffin used as a fire

562

retardant additive for polymers. Polym. Degrad. Stab. 1980,2(1), 23-33.

563

23. Bergman, A.; Hagman, A.; Jacobsson, S.; Jansson, B.; Ahlman, M., Thermal degradation

564

of polychlorinated alkanes. Chemosphere 1984,13(2), 237-250.

565

24. Schinkel, L.; Lehner, S.; Knobloch, M.; Lienemann, P.; Bogdal, C.; McNeill, K.; Heeb, N.

566

V., Transformation of chlorinated paraffins to olefins during metal work and thermal exposure

567

– Deconvolution of mass spectra and kinetics. Chemosphere 2018,194,803-811.

568

25. Cai, J., Production, market, and technology progress of chlorinated paraffin 70 (In

569

Chinese). China Chlor-Alkali 2000,9,22-26.

570

26. Data on manufacture, import, export, uses and releases of HBCDD as well as

571

information on potential alternatives to its use; ECHA report; 2009;

572

https://echa.europa.eu/documents/10162/13640/tech_rep_hbcdd_en.pdf/eb5129cf-38e3-4a25-

573

a0f7-b02df8ca4532

574

27. Gao, W.; Wu, J.; Wang, Y. W.; Jiang, G. B., Quantification of short- and medium-chain

575

chlorinated paraffins in environmental samples by gas chromatography quadrupole

576

time-of-flight mass spectrometry. J. Chromatogr. A 2016,1452,98-106.

577

28. Jordan, K. J.; Suib, S. L.; Koberstein, J. T., Determination of the Degradation Mechanism 30 ACS Paragon Plus Environment

Page 30 of 33

Page 31 of 33


578

from the Kinetic Parameters of Dehydrochlorinated Poly(vinyl chloride) Decomposition. The

579

Journal of Physical Chemistry B 2001,105(16), 3174-3181.

580

29. Yu, J.; Sun, L.; Ma, C.; Qiao, Y.; Yao, H., Thermal degradation of PVC: A review. Waste

581

Manag. 2016,48,300-314.

582

30. Sosa, J. M., Thermal stability of chlorinated paraffins. Journal of Polymer Science:

583

Polymer Chemistry Edition 1975,13(10), 2397-2405.

584

31. Schinkel, L.; Lehner, S.; Heeb, N. V.; Lienemann, P.; McNeill, K.; Bogdal, C.,

585

Deconvolution of Mass Spectral Interferences of Chlorinated Alkanes and Their Thermal

586

Degradation Products: Chlorinated Alkenes. Anal. Chem. 2017,89(11), 5923-5931.

587

32. McEnally, C. S.; Pfefferle, L. D.; Atakan, B.; Kohse-Höinghaus, K., Studies of aromatic

588

hydrocarbon formation mechanisms in flames: Progress towards closing the fuel gap. Progr.

589

Energy Combust. Sci. 2006,32(3), 247-294.

590

33. Weng, S. Fourier Transform Infrared Spectroscopy. Second Edition; Chemical Industry

591

Press: Beijing, 2010.

592

34. Lemieux, P. M.; Lutes, C. C.; Santoianni, D. A., Emissions of organic air toxics from

593

open burning: a comprehensive review. Progr. Energy Combust. Sci. 2004,30(1), 1-32.

594

35. Wang, Y.; Gao, W.; Jiang, G., Strengthening the Study on the Behavior and

595

Transformation of Medium-Chain Chlorinated Paraffins in the Environment. Environ. Sci.

596

Technol. 2017,51(18), 10282-10283.

597

36. Mosallanejad, S.; Dlugogorski, B. Z.; Kennedy, E. M.; Stockenhuber, M.; Lomnicki, S.

598

M.; Assaf, N. W.; Altarawneh, M., Formation of PCDD/Fs in Oxidation of 2-Chlorophenol on

599

Neat Silica Surface. Environ. Sci. Technol. 2016,50(3), 1412-1418. 31 ACS Paragon Plus Environment


600

37. Taylor, P. H.; Dellinger, B., Pyrolysis and molecular growth of chlorinated hydrocarbons.

601

J. Anal. Appl. Pyrolysis 1999,49(1), 9-29.

602

38. Procaccini, C.; Bozzelli, J. W.; Longwell, J. P.; Sarofim, A. F.; Smith, K. A., Formation of

603

Chlorinated Aromatics by Reactions of Cl•, Cl2, and HCl with Benzene in the Cool-Down

604

Zone of a Combustor. Environ. Sci. Technol. 2003,37(8), 1684-1689.

605

39. Oh, J.-E.; Gullett, B.; Ryan, S.; Touati, A., Mechanistic Relationships among PCDDs/Fs,

606

PCNs, PAHs, ClPhs, and ClBzs in Municipal Waste Incineration. Environ. Sci. Technol.

607

2007,41(13), 4705-4710.

608

40. Zhou, H.; Meng, A.; Long, Y.; Li, Q.; Zhang, Y., A review of dioxin-related substances

609

during municipal solid waste incineration. Waste Manag. 2015,36,106-118.

610

41. Sakai, S.-I.; Hayakawa, K.; Takatsuki, H.; Kawakami, I., Dioxin-like PCBs Released

611

from Waste Incineration and Their Deposition Flux. Environ. Sci. Technol. 2001,35(18),

612

3601-3607.

613

42. Yasuhara, A.; Katami, T.; Shibamoto, T., Formation of PCDDs, PCDFs, and Coplanar

614

PCBs from Incineration of Various Woods in the Presence of Chlorides. Environ. Sci. Technol.

615

2003,37(8), 1563-1567.

616

43. Lee, C. C.; Huffman, G. L., Innovative thermal destruction technologies. Environ. Prog.

617

1989,8,190-199.

618

44. Standard for pollution control on the municipal solid waste incineration. Ministry of

619

Ecology and Environment, PRC.,2014; http://kjs.mep.gov.cn/hjbhbz/bzwb/gthw/gtfwwrkzbz/

620

201405/W020140530531389708182.pdf.

621

45. Katami, T.; Yasuhara, A.; Okuda, T.; Shibamoto, T., Formation of PCDDs, PCDFs, and 32 ACS Paragon Plus Environment

Page 32 of 33

Page 33 of 33


622

Coplanar PCBs from Polyvinyl Chloride during Combustion in an Incinerator. Environ. Sci.

623

Technol. 2002,36(6), 1320-1324.

624

46. Li, Y.; Yang, Y.; Yu, G.; Huang, J.; Wang, B.; Deng, S.; Wang, Y., Emission of

625

unintentionally produced persistent organic pollutants (UPOPs) from municipal waste

626

incinerators in China. Chemosphere 2016,158,17-23.

627

47. Richter, H.; Howard, J. B., Formation of polycyclic aromatic hydrocarbons and their

628

growth to soot—a review of chemical reaction pathways. Progr. Energy Combust. Sci.

629

2000,26(4–6), 565-608.

630

48. Richter, H.; Benish, T. G.; Mazyar, O. A.; Green, W. H.; Howard, J. B., Formation of

631

polycyclic aromatic hydrocarbons and their radicals in a nearly sooting premixed benzene

632

flame. Proceedings of the Combustion Institute 2000,28(2), 2609-2618.

633

49. Van den Berg, M.; Birnbaum, L. S.; Denison, M.; De Vito, M.; Farland, W.; Feeley, M.;

634

Fiedler, H.; Hakansson, H.; Hanberg, A.; Haws, L.; Rose, M.; Safe, S.; Schrenk, D.; Tohyama,

635

C.; Tritscher, A.; Tuomisto, J.; Tysklind, M.; Walker, N.; Peterson, R. E., The 2005 World

636

Health Organization reevaluation of human and mammalian toxic equivalency factors for

637

dioxins and dioxin-like compounds. Toxicol. Sci. 2006,93(2), 223-241.

638

50. Xu, F.; Zhang, R.; Li, Y.; Zhang, Q.; Wang, W., Theoretical Mechanistic and Kinetic

639

Studies on Homogeneous Gas-Phase Formation of Polychlorinated Naphthalene from

640

2-Chlorophenol as Forerunner. Int. J. Mol. Sci. 2015,16(10), 25641-25656.

641


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