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题名: 炼焦过程中典型UP-POPs的生成和排放研究
作者: 刘国瑞
学位类别: 博士
答辩日期: 2010
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 郑明辉
关键词: 持久性有机污染物 ; 二恶英类 ; 多氯联苯 ; 多氯萘 ; 炼焦
中文摘要:       在炼焦过程中会产生和排放多环芳烃(PAHs)等芳烃化合物,并且,许多研究已经证实二恶英类(PCDD/Fs)和多氯萘(PCNs)等非故意产生的持久性有机污染物(UP-POPs)可以通过PAHs等芳烃化合物的反应生成。因此,我们推断炼焦工艺是PCDD/Fs和PCNs等典型UP-POPs的一类潜在源,然而,目前对炼焦过程中几类典型UP-POPs生成和排放的系统研究尚属空白。 本研究以11家典型焦化厂为研究对象,对炼焦过程中二恶英类、多氯联苯(PCBs)、多氯萘、六氯苯(HxCBz)和五氯苯(PeCBz)的生成途径、排放特征和大气排放水平进行了系统研究,所获得的主要研究结果如下: 1. 首次系统研究了炼焦过程中典型UP-POPs的排放特征。对于PCDD/Fs,OCDD, 1234678-HpCDD, 1234678-HpCDF和OCDF是17种2378-PCDD/Fs的主要单体。对于类二恶英多氯联苯(dl-PCBs),CB-118是最主要的单体,而对dl-PCBs毒性当量贡献最大的单体是CB-126。至于PCNs,随着氯取代数目的增加,同系物的百分含量逐渐降低,MonoCN是最主要的同系物。而几类典型UP-POPs的浓度特征为:PCNs > dl-PCBs > PCDFs ≈ PeCBz ≈ HxCBz > PCDDs。 2. 提出了炼焦行业典型UP-POPs的排放因子,评估了全球炼焦行业典型UP-POPs的排放量。炼焦过程PCDD/Fs的排放因子为28.9 ng WHO-TEQ tonne-1, dl-PCBs是1.7 ng WHO-TEQ tonne-1, PCNs为1.0 ng TEQ tonne-1, HxCBz为596 ng tonne-1, PeCBz是 680 ng tonne-1。根据提出的排放因子,对全球炼焦行业典型UP-POPs的年排放量进行了估算, PCDD/Fs的年排放量为15.8 g WHO-TEQ, dl-PCBs是0.93 g WHO-TEQ, PCNs为0.56 g TEQ, HxCBz为333 g, PeCBz为379 g,这些数据为估算炼焦行业典型UP-POPs的排放水平提供了数据支持。 3. 依据典型UP-POPs的分布特征,提出了PCDD/Fs和PCNs的主要生成机制。二恶英类的分布特征表明:炼焦过程中PCDD/Fs的排放主要是以PCDFs为主,PCDDs的含量相对较低,因此de novo合成是炼焦过程二恶英类生成的主要途径。对于PCNs,其分布特征和同系物间的相关性分析表明,氯化是炼焦过程中PCNs生成的重要途径。
英文摘要:       Formation and emission of polycyclic aromatic hydrocarbons (PAHs) during coking processes has been widely recognized. Formation of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated naphthalenes (PCNs) from PAHs during some thermal related processes has been confirmed in many studies. Thus, coking process is assumed to be a potential source of UP-POPs. However, intensive study on formation and emission of UP-POPs during coking process has not been reported to our knowledge. An intensive study on formation and emission of PCDD/Fs, PCBs, PCNs, HxCBz and PeCBz were carried out. Stack gas samples from eleven typical coke plants were collected by automatic isokinetic sampling techniques. And the selected UP-POPs were qualified and quantified by isotope dilution HRGC/HRMS technique. The obtained results were presented as follows. 1. The emission characteristics of the selected UP-POPs during coking processes were detailed presented. With regard to PCDD/Fs, four congeners comprised of OCDD, 1234678-HpCDD, 1234678-HpCDF and OCDF were the predominant species. For dl-PCBs, the most abundant congener was CB-118, and the most dominant contributor to total WHO-TEQ of dl-PCBs was CB-126. With regard to the characteristics of PCNs, PCNs profiles were dominated by the lower chlorinated homologues, with the most abundant of MonoCN. The profiles of the selected UP-POPs were as follows: PCNs > dl-PCBs > PCDFs ≈ PeCBz ≈ HxCBz > PCDDs. 2. The emission factors of selected UP-POPs for coking processes were derived and the emission amout of selected UP-POPs from coking industry were estimated. Emission factors of 28.9 ng WHO-TEQ tonne-1 for PCDD/Fs, 1.7 ng WHO-TEQ tonne-1 for dl-PCBs, 1.0 ng TEQ tonne-1 for PCNs, 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, 0.56 g TEQ for PCNs, 333 g for HxCBz, and 379 g for PeCBz, respectively. These results might provide helpful data for understanding the levels of UP-POPs and developing POPs inventory. 3. The dominant formation pathway of PCDD/Fs and PCNs were speculated based on the characteristics of selected UP-POPs. According to the distribution of PCDD/Fs, we argued for the de novo synthesis to be the major pathway of PCDD/Fs formation. It was speculated that chlorination are possibly the dominant pathway of PCNs formation during coking process according to the PCN distribution and correlations of PCN homologues. The results obtained in this study were helpful for understanding formation mechanism of PCDD/Fs and PCNs during coking process.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35037
Appears in Collections:环境化学与生态毒理学国家重点实验室_学位论文

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Recommended Citation:
刘国瑞. 炼焦过程中典型UP-POPs的生成和排放研究[D]. 北京. 中国科学院研究生院. 2010.
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