低氯代二恶英类在废物焚烧和典型化工产品中分布特征研究
文献类型：学位论文
| 作者 | 田振宇 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘文彬 |
| 关键词 | 低氯代二恶英 烟气 化工产品 排放特征 生成机制 less chlorinated dioxins stack gas chemicals emission profile formation mechanism |
| 其他题名 | Distribution profiles of less chlorinated dioxins in waste incineration and typical chemical products |
| 学位专业 | 环境科学 |
| 中文摘要 | 二恶英类（PCDD/Fs）是一类在环境中普遍存在的，危害较大，且广受公众关注的持久性有机污染物（POPs）。了解各种污染源中二恶英类的排放特征和生成机制，是控制和削减这类污染物的基础。已有的对于二恶英类的大多数研究都集中在 17种 2,3,7,8位氯代的二恶英同类物及其从属的四至八氯代同系物，而对一至三氯代的低氯代二恶英类同系物及其所含同类物的研究较少。本研究以了解二恶英类的排放特征和生成机制为目的，建立了低氯代二恶英类的前处理和分析方法。并使用这一方法，检测了废弃物焚烧厂的烟气样品和典型化工产品中的低氯代二恶英类，通过分析其排放特征，对不同源的二恶英类生成机制做出推测。 所获得的主要研究成果如下： （1）本研究建立了低氯代二恶英类的分析方法。首先利用原生和同位素标记的标准品，参照文献研究，在气相色谱四级杆质谱联用仪（HRGC/qMS）和高分辨气质联用仪（HRGC/HRMS）上建立并改进了低氯代二恶英类的仪器测定方法。使用 HRGC/HRMS通过校正曲线确定了目标物在仪器上的相对响应因子（RRF）和线性范围。在使用二恶英类标准前处理方法对低氯代二恶英进行分离净化时，发现了低氯代二恶英类与酸性硅胶中的硫酸反应而被分解的现象。随后经反复试验，以碱性氧化铝流出曲线为核心，发展出针对低氯代二恶英类的前处理方法，检出限（LOD）为 0.03-0.5 ng/L，加标回收率在 66%-112%。 （2）本研究对典型废弃物焚烧烟气样品中的一至八氯代二恶英类进行了测定和特征分析。从两个城市固体废弃物焚烧厂和两个医疗废弃物焚烧厂采集了烟气样品，分别分析其中全氯代二恶英类污染物。在烟气样品中，PCDF总体浓度水平高于 PCDD，尤其以低氯代 PCDF同系物为主。PCDF的同系物分布特征为，浓度随氯代程度增加而减少，呈阶梯状分布。PCDD同系物特征变化较小。大部分样品中最主要的 PCDF同类物为 2-MoCDF，浓度范围是 0.58-35.9 ng/Nm，最类的 D/F比值和氯化度，我们发现 TEQ（Toxic Equivalent）较低的烟气中含有较多的低氯代二恶英类，和较高的 D/F比。另外，同类物 2,8-DiCDF，2,4,8-TrCDF 和同系物 DiCDF，TrCDF都和二恶英类的毒性当量（TEQ）存在较强的相关性，因而是潜在的 TEQ指示物。进一步研究发现，2,8-DiCDF，2,4,8-TrCDF这两种低氯代同类物和 TEQ的主要贡献者 2,3,4,7,8-PeCDF的相关性很高。从而推测，从低氯代到高氯代逐级氯代的生成机制可能在焚烧中 PCDF类的形成中占有重要地位。 （3）本研究对典型化工产品中的一至三氯代二恶英类进行了测定和特征分析。在四氯苯醌、2,4-D及其丁酯以及对二氯苯样品中，提取并检测出了低氯代二恶英类。对于四氯苯醌，不同样品中二恶英类浓度水平差异很大，其中三氯代同系物 TrCDF浓度最高。与相同样品中的高氯代同系物相比，低氯代同系物浓度较低，说明四氯苯醌中的二恶英类杂质主要是高氯代为主。2,4-D丁酯样品中低氯代二恶英类以DiCDF、TrCDF为主，其中DiCDF浓度最高，为31.1-83.2ng/g，三氯代同系物次之。2,4-D酸中也以低氯代呋喃同系物为主，特征因样品而有所差异。对二氯苯中主要检出一二氯呋喃同系物，但浓度水平较低。二三氯代同系物基本无检出。 |
| 英文摘要 | PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans)are a class of ubiquitous, harmful, and widely concerned persistent organic pollutants(POPs). Understanding the emission profile and formation mechanism of arious sources of dioxins, is the basis of control and inhibition of such pollutants. Most of the researches on dioxins have been focused in 17 2,3,7,8-chlorinated congeners and tetra-to octa- chlorinated homologues that they belong, while mono- to tri- chlorinated homologues and their congeners are rarely studied. In this study, we established pre-treatment and analytic method for less chlorinated dioxins and furans in order to understand the emission and formation mechanism. Contaminants were measured in typical chemicals and stack gas samples from waste incineration plants, using the method established. And the possible formation mechanism were proposed. The main results obtained are as follows: (1) In present study, analytic methods of less chlorinated dioxins were established. Firstly, instrumental methods were developed and optimized in high resolution gas chromatography-quadrupole mass spectrometry (HRGC/qMS) and high resolution gas chromatography- high resolution mass spectrometry(HRGC/HRMS) with native and isotope labeled standards, according to study literatures. Relative response factor (RRF)and linear range of target compounds were determined on HRGC/HRMS with calibration curve. When applied standard pretreatment methods to the purification of less chlorinated dioxins, a decomposition of less chlorinated dioxins, due to the reaction with sulfuric acid in acidic silica gel, were observed. Then after repeated trials, a special pre-treatment method for the less chlorinated dioxins, with the core of basic alumina elution curve, was developed. Tested limits of detection (LOD) were 0.03-0.5 ng/ L,and recoveries were at 66 % -112 %. (2) In this study, mono- to octa- chlorinated dioxins were determined and analyzed in stack gas samples from two municipal solid waste incineration plants and two medical waste incineration plants. In stack gas samples, PCDF homologue concentration levels were higher than those of PCDD, especially less chlorinated PCDF homologues. A ladder shaped profile suggested that concentration of each PCDF homologue decreased with increasing chlorination level. PCDD homologue profiles varied in a smaller degree. Dominant congener in all PCDD/Fs was 2-MoCDF, and the concentration range is 0.58-35.9 ng/Nm3. The main PCDD congener was OCDD, with. Through the analysis of dioxins D/F ratio a concentration range of 021-2.16 ng/Nm3 and the degree of chlorination, we found that stack gas samples with low TEQ (Toxic Equivalent) had higher proportions of the less chlorinated homologues and lower D/F ratios. 2,8-DiCDF, 2,4,8-TrCDF, DiCDF, and TrCDF can be used as TEQ indicators for monitoring PCDD/Fs. because they correlated well with TEQ. Further study showed that, 2,8-DiCDF, 2,4,8-TrCDF correlated well with 2,3,4,7,8-PeCDF, a major contributor of TEQ. Thus, it is presumed that a stepwise chlorination pathway may play an important role in the formation of PCDF in incineration. (3) In current study, mono- to tri- chlorinated dioxins were measured and analyzed in typical chemical products. Less chlorinated dioxins in chloranil, 2,4-D and 1,4-dichlorobenzene samples were extracted and determined. For chloranil, levels of concentration varied among samples, and TrCDF was the homologue with highest concentration. Compared with higher chlorinated homologues in the same samples,concentrations of less chlorinated congeners were low, indicating that dioxin impurities in chloranil were mainly high chlorinated. DiCDF, TrCDF were predominant homologues in 2,4-D butyl ester samples. DiCDF presented a highest concentration at 31.1-83.2 ng/g, followed by trichlorinated furan. Major homologues in 2,4-D acid samples were also lower chlorinated furans, and the profiles varied. Monochlorinated furans were detected in 1,4-dichlorobenzene samples, but the concentrations were low.Di- and tri- chlorinated homologues were seldom detected. |
| 公开日期 | 2015-06-12 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13456]  |
| 专题 | 生态环境研究中心_环境化学与生态毒理学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 田振宇. 低氯代二恶英类在废物焚烧和典型化工产品中分布特征研究[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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