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题名: 典型工业热过程中PCDD/Fs 的生成与排放
作者: 王美1
学位类别: 博士后
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 王效科 ; 郑明辉
关键词: 二恶英类 ; 工业热过程 ; PCDD/Fs ; 排放水平 ; 2,3,7,8-substituted-PCDD/Fs ; 排放特征 ; non-2,3,7,8-substituted- PCDD/Fs ; 生成机制 ; Industrial thermal processes ; emission characteristics ; formation mechanism
学位专业: 生态学
中文摘要: 二恶英类(PCDD/Fs)是一类在环境中普遍存在的,能够通过多种途径进行 区域甚至全球范围迁移分配,并能够通过食物链蓄积,进而对环境和人体健康造 成威胁的持久性有机污染物(POPs)。工业热过程是环境中PCDD/Fs 的主要来源 之一。了解工业热过程中PCDD/Fs 的排放特征和生成机制对PCDD/Fs 源排放控 制具有重要的意义。目前,对于工业热过程中PCDD/Fs 的生成和排放已经有大 量的报道,但是已有的大多数研究都主要集中在17 种2,3,7,8 位氯取代的二恶英 同类物(2,3,7,8-substituted-PCDD/Fs)上,而对于总二恶英类和非2,3,7,8 位氯取 代的二恶英同类物(non-2,3,7,8-substituted-PCDD/Fs)的研究较少。 仅关注于17 种2,3,7,8-substituted-PCDD/Fs 同类物的排放,忽略non-2,3,7,8- substituted-PCDD/Fs 同类物在这些热过程中的参与可能会造成工业热过程中 PCDD/Fs 的识别和量化存在一定程度的不确定性,进而影响工业热过程中 PCDD/Fs 的总体评估。同时,研究和探讨PCDD/Fs 的生成机制,不仅要关注于 17 种2,3,7,8-substituted-PCDD/Fs 同类物的生成水平和生成特征,还应考虑一些 non-2,3,7,8-substituted-PCDD/Fs 同类物的生成水平及特征,以此对PCDD/Fs 进 行整体评估,进而推断出PCDD/Fs 在工业热过程中可能的生成途径。 本研究在前期研究的基础之上,着眼于工业过程中潜在的排放源和已识别的 工业源,选取了产量权重较大的铁矿石烧结、再生铜冶炼、再生铝冶炼、镁冶炼 和焚烧炉焚烧导线回收有色金属在内的五类典型工业热过程作为调查对象,对这 些热过程中PCDD/Fs 的排放水平、排放特征、生成机制以及2,3,7,8-substituted- PCDD/Fs 和non-2,3,7,8-substituted-PCDD/Fs 之间的相关性进行了系统的研究。 通过对结果的分析,得出以下结论: 1、研究量化了多种典型工业热过程中PCDD/Fs 的排放水平,识别了工业热 过程中2,3,7,8-PCDD/Fs 与non-2,3,7,8-PCDD/Fs 的相对排放水平,发现对于低氯同类物(TeCDD/Fs),2,3,7,8-substituted-PCDD/Fs 的排放浓度低于non-2,3,7,8- substituted-PCDD/Fs 的排放浓度,对于高氯代同类物(HpCDD/Fs),2,3,7,8- substituted-PCDD/Fs 的排放浓度远高于non-2,3,7,8-substituted-PCDD/Fs 的排放浓 度,占到相应氯代同类物排放总浓度的63–96%,起主导作用;研究还进一步揭 示了典型工业热过程中PCDD/Fs 的排放特征,发现2,3,7,8-substituted-PCDD/Fs 和non-2,3,7,8-substituted-PCDD/Fs 的同类物之间呈现较好的相关性。 2、在现场研究的基础上,研究以实际再生铜冶炼过程中产生的布袋灰作为 反应的基质,设计并开展了实验室模拟反应,对PCDD/Fs 的生成机理和影响因 素进行了进一步探索。通过对反应产物的分析,研究发现再生铜布袋灰历经热反 应后有显著的2,3,7,8-substituted-PCDD/Fs 和non-2,3,7,8-substituted-PCDD/Fs 的 生成,其生成增量可达百倍。其中2,3,7,8-substituted-PCDD/Fs 的生成水平远高于 non-2,3,7,8-substituted-PCDD/Fs 的生成水平,起主导作用。通过相关性分析、同 系物分布变化趋势分析、同类物比较分析以及关键中间产物的定性定量分析,发 现氯化反应是再生铜冶炼过程中PCDD/F 生成的重要机理之一。 上述研究结果将有助于了解研究典型工业热过程中PCDD/Fs 生成与排放, 识别其排放特征,整体量化其排放水平以及进一步明确其生成机制,这些成果将 为优化工艺技术和污染控制技术提供科学依据,以达到控制和削减典型工业热过 程中PCDD/Fs 的生成和排放的目的。
英文摘要: Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are highly toxic compounds that are found widely in environmental media, can be transported at the regional and global scales, and accumulated through the food chain, and han threaten environmental and human health. Industrial thermal processes are considered to be major sources of PCDD/Fs. Studies of the factors that influence the formation of PCDD/Fs and the mechanisms involved in PCDD/Fs formation are important because they provide information that will allow techniques for decreasing PCDD/Fs emissions to be developed. Although a large portion of the literature on the formation and emissions of dioxin-like compounds from industiral thermal processes has foused on 2,3,7,8-substituted-PCDD/Fs,fewer studies have focused on total PCDD/Fs and non- 2,3,7,8-substituted PCDD/Fs , especially regarding their emission level and characteristics from stack gas relative to different industrial thermal processes. Based on previous investigations, five types industridual thermal processes, including iron ore sintering, secondary copper smelting, secondary aluminum smelting, magnesium smelting, and thermal wire reclamation processes were selected as sampling sites in this study. The formation and emission of PCDD/Fs, the relationship between 2,3,7,8-substituted-PCDD/Fs and non-2,3,7,8-substituted-PCDD/Fs were investigated in detail. The results are presented below. 1. Field studies were conducted elucidating the emission characteristics of PCDD/Fs during different industridual thermal processes, including iron ore sintering, secondary copper smelting, secondary aluminum smelting, magnesium smelting, and thermal wire reclamation processes. The relative importance of 2,3,7,8-substituted PCDD/Fs and non-2,3,7,8-substituted-PCDD/Fs were assessed, and the 2,3,7,8- substituted-PCDD/Fs were found be dominant. For the less chlorinated-PCDD/Fs, the emission levels of 2,3,7,8-substituted-PCDD/Fs were lower than non-2,3,7,8- substituted-PCDD/Fs; for the more chlorinated-PCDD/Fs, the emission levels of 2,3,7,8-substituted-PCDD/Fs were higher than non-2,3,7,8-substituted-PCDD/Fs. 2. On the basis of the results of the field studies, a series of laboratory-scale experiments to simulate the thermal formation of PCDD/Fs in a secondary copper smelter were performed using fly ash as the reaction matrix. The mechanisms involved in the formation of PCDD/Fs were investigated under different thermal conditions. High 2,3,7,8-substituted-PCDD/F and non-2,3,7,8-substituted-PCDD/F concentrations, which were about two orders of magnitude higher than the initial 2,3,7,8-substituted- PCDD/F and non-2,3,7,8-substituted-PCDD/F concentrations in the fly ash, were found after the fly ash had been heated for less than 10 min. The formation of PCDD/Fs was found to occur at between 250 and 450 °C, but more PCDD/Fs were formed at 350 °C than at lower temperatures. The more-chlorinated congeners were the dominant congeners that were formed. Correlation, homologue profile, and congener pattern analyses were performed and key intermediate products were quantified, and the results indicated that the chlorination mechanism was an important PCDD/Fs formation pathway. The results of this study might help in the development of techniques for controlling PCDD/F emissions during secondary copper smelting processes.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38701
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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