بخشی از مقاله انگلیسی:
The emission rates of polybrominated diphenyl ethers (PBDEs) from electric/electronic products during their use and disposal were estimated. E-wastes, including televisions and refrigerators, gathered at recycling centers were also analyzed to estimate their emissions. The average concentrations of PBDEs in TV rear covers produced before and after the year 2000 were 145,027 mg/kg and 14,049 mg/kg, respectively. The PBDEs concentration in TV front covers was lower than the concentration in TV rear covers. The concentration in the components of the refrigerator samples ranged from ND to 445 mg/kg. We estimated the atmospheric emissions of PBDEs based on the concentrations. The annual emissions from TV rear covers produced before 2000 were calculated to be approximately 162.1 kg and after 2000, the annual emissions were 18.7 kg. Refrigerators showed the lowest annual emissions of PBDEs (0.7 kg). The atmospheric concentrations were also measured to calculate emissions generated during the recycling process. The highest concentration was 16.86 ng/m3 emitted from the TV sets during the dismantling process. The concentrations of PBDEs generated in the plastic processing field ranged from 2.05 to 5.43 ng/m3 depending on the products, and ambient air in open-air yards showed concentrations in the range of 0.32 to 5.55 ng/m3 . Emission factors for the recycling process were calculated using the observed concentrations. The estimated emissions according to the emission factors ranged from 0.3 × ۱۰−۱ to 90.3 kg/year for open-air yards and from 0.1 × ۱۰−۱ to 292.7 kg/year for the dismantling and crushing processes of TV set, depending on the production year.
Most plastics used in electrical and electronic equipment such as televisions, washing machines and refrigerators contain a variety of flame retardants. Flame retardants are physically and chemically derived materials that consist of organic compounds containing carbon, hydrogen and oxygen rendered incombustible by additives (Covaci et al., 2011). Some PBDEs were recently banned in the Fourth Meeting of the Conference of the Parties to the Stockholm Convention, although the PBDEs possess extensive industrial applications and are widely used (Stockholm Convention, 2009). Diphenyl ether molecules contain ten hydrogen atoms, any of which can be exchanged with bromine to result in 209 possible congeners (Alaee et al., 2003). Major commercial PBDEs include deca-BDE (decabromodiphenyl ether), octa-BDE (octabromodiphenyl ether) and penta-BDE (pentabromodiphenyl ether) (Sjödin, 2000). These compounds are highly bioaccumulative and are classified as endocrine disruptors that cause reproductive disorders and hepatotoxicity (US EPA, 2008a,b,c,d). The use of brominated flame retardants causes the worst effects on the environment. The European Union (EU) therefore decided to ban the use of penta-BDE and octa-BDE (Birnbaum and Staskal, 2004). The production and use of these two BDEs were prohibited worldwide in the 1990s (Cischem, 2009). The EU regulations such as the RoHS (Restriction of the Use of Hazardous Substances in electrical and electronic equipment) and the WEEE (Waste Electrical and Electronic Equipment) banned the use of PBDEs due to their harmful environmental and health effects (Cischem, 2009). Until 2006, a wide array of products made in the Republic of Korea such as computers, TV sets and automobiles used brominated flame retardants (MOE of Korea, 2010). Environmental regulations in Korea have restricted the use of brominated flame retardants since 2006 (Business Service Center for Global Environmental Regulation, 2010). Due to their human toxicity and environmental issues, many countries have conducted research and studies relative to effective management of PBDEs. The Ministry of Environment of Korea has calculated the emissions for some deca-BDE emissions only during manufacturing, and the data available on the emissions of PBDEs to the atmosphere of Korea are therefore very limited (Korea NIER, 2011). However, Japan has presented data on the national emissions and emission factors for PBDEs emitted during the life cycle of PBDEs-containing products from production to disposal (Sakai et al., 2006). The Ministry of the Environment of Japan showed that emissions from the recycling process accounted for 32% of the total atmospheric emissions from waste electrical and electronic equipment (MOE of Japan, 2003). However, there is a lack of studies assessing the impact of e-waste recycling (Tsydenova and Bengtsson, 2011). To the best of our knowledge, there is especially no report available concerning emissions of PBDEs released during the use of appliances or from the recycling process for e-waste in the Republic of Korea. Hard data on emissions in the indoor environment at e-waste recycling facilities are required to support risk assessment and establish some guidelines that seem to be lacking at present (Tsydenova and Bengtsson, 2011). In this study, TV sets and washing machine were used as the key discarded home appliances to investigate the characteristics of PBDEs by year of production and by component. The atmospheric concentrations were also measured during the recycling process of e-waste and used to calculate the emission factors. These two results were then used to estimate the PBDEs emissions generated during the life cycle of products, especially at the time of use and recycling, which accounts for high release levels.
۲٫ Materials and methods
۲٫۱٫ Collection and preparation of samples
Among all the TV parts, the front and rear covers are supposed to contain the major portion of the flame retardants, especially PBDEs (Japan NIES, 2011; Tamade et al., 2002). Crushed TV sets produced during the early 1980s and the mid-2000s were collected from the recycling center, and the details are presented in Table 1. Refrigerator samples produced during the year 2002 (before the regulation came into effect) were collected. These refrigerators were disassembled into components to study the different flame retardants used in each part. These samples were collected from the recycling center. Only home appliances (TV sets, refrigerators, washing machines and air conditioners) are being recycled in domestic recycling centers. Korea has seven recycling centers, and the weight of TV sets, refrigerators, washing machines and air conditioners collected at these recycling centers is approximately 15.5 × ۱۰۳ t, 45.4 × ۱۰۳ t, 23.6 × ۱۰۳ t and 2.2 × ۱۰۳ t, respectively. TV sets and refrigerators account for more than 57% of the appliances entering recycling facilities. Researchers have previously reported that the PBDE contents of TV sets are very high (Sakai et al., 2006). Based upon the highest quantities of target products (TV sets, refrigerators, washing machines, etc.) entering recycling facilities and previous results, two recycling centers termed ‘A-RC’ and ‘B-RC’ were selected for the sampling. When compared to the total number of recycling centers in Korea, the collected appliances from the two selected recycling centers account for 32% of the contents of the seven domestic recycling centers, and only three recycling centers are dealing with TV sets, with approximately 35% at A-RC. Air samples were collected from areas such as dismantling, crushing/plastic segregation and the open-air yard containing the piles of the waste products at A-RC (Fig. 1). At B-RC, the sampling was performed at the crushing/plastic segregation area and the open-air yard but not at the dismantling area (because of practical difficulties). Some background samples were also collected from the B-RC area boundary, located approximately 100 m from the working area. A-RC and B-RC are approximately 82 km away. For sampling, a high volume air sampler (HVAS) (Model HV-1000F, SIBATA Inc.) was installed at three locations at each of the two RCs (A-RC and B-RC) in October 2012. Particles were collected by passing air through a quartz fiber filter with a size of 203 × ۲۴۵ mm. Pollutants in the gas phase were collected on polyurethane foam (PUF), diameter 85 mm and thickness 50 mm. Samples were collected for an average sampling period of 48 h. The mean flow rate for each sample collected was approximately 1000 L/min.
The plastic samples selected for analysis were cut into approximately 5 mm × ۵ mm pieces, infused with liquefied nitrogen, frozen for 1 min, and then turned into particles less than 1 mm in size using VSRM (Variable Speed Rotor Mill). The IEC 62321 method was used to analyze the PBDEs contained in the TV covers and refrigerator plastics that were sampled (IEC, 2008). Approximately 20 μL of internal standard (CB-209; 10 μg/mL) and 100 mL of toluene were added to 0.1 g of powdered sample, and the sample was extracted for 30 min using a supersonic wave extractor. The sample was subjected to instrumental analysis after adjusting the total volume of the solvent lost during extraction and filtering. PBDEs were determined by gas chromatography/mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode using a DB5-HT column (15 m × ۰٫۲۵ mm i.d., 0.1 μm, J&W Scientific). The sample was analyzed for thirteen isomers (BDE-3, BDE15, BDE-33, BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, BDE-203, BDE-206, and BDE-209).
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