Influence of metallic chlorides on the formation of PCDD/Fs during low-temperature oxidation of carbon.
Influence of metallic chlorides on the formation of PCDD/Fs during low-temperature oxidation of carbon.
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DOI：
10.1021/es034041h
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发表时间：
2003-04
影响因子：
11.4
通讯作者：
S. Kuzuhara;H. Sato;E. Kasai;T. Nakamura
中科院分区：
文献类型：
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作者：
S. Kuzuhara;H. Sato;E. Kasai;T. Nakamura
实验研究了以碳质材料为原料，通过新合成途径生成多氯二苯并对二恶英（pcdd）和多氯二苯并呋喃（pcdf）的行为。通过改变石墨粉中金属氯化物的混合方式和复合状态制备样品，模拟热过程中形成的“未燃烧的碳质颗粒”即烟灰的结构。KCl， CaCl2的试剂。以2H2O、FeCl3 x 6H2O和CuCl2 x 2H2O为氯源，采用不同的方法添加到石墨粉中。通过手工搅拌、高强度球磨机混磨、500 ~ 1100℃不同温度预热等初步处理，改变了金属氯化物的复合状态。在重新实验中，反应温度为300℃，流动气体氧浓度为2.5 mol %。实验过程中测定了CO和CO2的生成速率、有机氯和PCDD/Fs的生成量。结果表明，有机氯的生成量与碳的氧化速率之间存在合理的关系，金属氯的活性大小为KCl < CaCl2 < FeCl3 < CuCl2。此外，还发现金属氯化物的复合状态对PCDD/Fs形成的影响与金属的种类有显著的关系。该结果将为研究未燃烧碳颗粒在热过程中形成PCDD/Fs的机理提供有用的信息。
Experimental study was conducted to clarify the formation behavior of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from carbonaceous materials through a de novo synthesis route. Samples were prepared by changing mixing method and composite state of metallic chloride in graphite powder in order to simulate the texture of "unburned carbonaceous particles", i.e., soot, formed in thermal processes. Reagents of KCl, CaCl2. 2H2O, FeCl3 x 6H2O, and CuCl2 x 2H2O were used as chlorine sources and were added to graphite powder with different methods. The composite state of metallic chloride was varied by preliminary treatments: hand-mixing, mixed-grinding using a high-intensity ball mill, and preheating at different temperatures between 500 and 1100 degrees C. In the de novo experiment, reaction temperature and oxygen concentration of flowed gas were set at 300 degrees C and 2.5 mol %, respectively. During the experiment, formation rates of CO and CO2 and the formed amounts of organic chlorine and PCDD/Fs were measured. The results show a reasonable relation between the amount of formed organic chlorine and oxidation rate of carbon, and the order of the activity of metallic chlorines was obtained as KCl < CaCl2 < FeCl3 << CuCl2. Furthermore, it was found that the effect of the composite state of metallic chloride on the formation of PCDD/Fs significantly depends on the kind of metal. The results will give useful information to examine the formation mechanism of PCDD/Fs from unburned carbon particles in thermal processes.