排放源污染微粒碎形型態與化學組成之特徵研究

Fractal Dimension and Chemical Composition of Suspended Particulates Emitted from Pollution Sources

張嘉宏(Chia-Hung Chang)

指導教授 ： 李慧梅

國立臺灣大學/工學院/環境工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01593

摘要

近年來對於各污染源對各地方的貢獻量之方法，主要是以污染源及受體點的採樣，經由物化分析後，再配合各種受體模式去推估污染源對受體點的貢獻量，此方法涉及大量化學分析，費時且成本高，因此，本研究分別挑選移動性污染源(柴油車)與固定性污染源(電弧爐煉鋼廠)微粒直接利用單一顆粒的鑑定方法，藉由電子顯微鏡微影技術建立排放源微粒之圖譜系統，並藉碎形模式的使用，計算出微粒二維之獨特碎形參數，最後配合化學分析方法，進而得到單一污染微粒之資料庫。由本研究主要貢獻，為建立起兩種不同排放源單一顆粒物化特性資料庫，可提供未來研究不明污染微粒之比對基礎。
從SEM微影圖顯示11部柴油車所排放柴油黑煙微粒型態都非常的相似，大部分皆為塊狀或鏈狀的聚集體，粒徑介於100~1000 nm之間，在碎形分析研究中，挑選出柴油車黑煙微粒聚集體之SEM10萬倍微影圖進行碎形模式分析，框架選取為65×65~80×80像素，得到平均碎形參數值介於0.225~0.359間，碎形維度則為1.641~1.775間，若與標準樣品(柴油動力計)之碎形維度(1.626~1.806)做比對，是落於一個合理的範圍內。於不同柴油車碎形參數比較中，得到當柴油車排氣量增加時，聚集體碎形參數值則有降低之趨勢;車齡增加時，碎形參數則有上升之趨勢;而里程數增加，碎形參數則沒有明顯的改變。
另外電弧爐煉鋼廠煙道微粒經由SEM顯微攝影可得到其微粒形狀複雜，有圓形、長柱形、三角錐型、多面體形等等，這些形狀都類似於金屬微粒之型態。然而，大部分電弧爐煉鋼微粒都以聚集體的型態出現，我們就利用碎形分析，框架選取為30×30~40×40像素，經統計得方法計算，得到碎形參數值介於0.469~0.633，平均碎形維度為1.449。
在單一顆粒EDS化學分析中，不同柴油車黑煙聚集體當其選取的粒徑越大，碳含量也隨之升高，顯示柴油車聚集體之化學組成主要以碳為主，除此之外，於分析中也發現黑煙微粒也含有重金屬的元素存在，如Fe, Zn, Mn, Cr元素。電弧爐煉鋼聚集體則分析出許多的元素(C, Na, S, Fe, Zn, Mn, Mg, Cr, Al等)，若依元素重量百分比分類，聚集體則以Fe, Zn金屬元素為主要組成。
關鍵字:單一顆粒鑑定、柴油車、電弧爐煉鋼、碎形維度、化學分析

關鍵字

單一顆粒鑑定 ； 柴油車 ； 電弧爐煉鋼 ； 碎形維度 ； 化學分析

並列摘要

In recent years, the approaches to determine the pollution source contribution are primarily sampling the pollution and the receptor points. Traditionally, we can determine the pollution source contribution after sampling by means of the physical and chemical analysis. However, these approaches are complicated and difficult. In light of this, we chose the diesel car and steel-making pollution source to conduct the research. Size, morphology, hurst coefficient, fractal dimension, and chemical elements of the single particle were investigated by scanning electron microscopy(SEM), energy-dispersive spectrometer(EDS) and fractal model analysis.
A lot of aggregates were observed in the SEM micrographs. The result indicated that the soot particles emitting from the elevent diesel cars are similar in the morphology. These aggregates are formed by condensation or aggregation of primary particles. Fractal properties of diesel soot aggregates were determined by fractal model. The hurst coeffricent of diesel soot aggregates in the 105 magnification images is about 0.225~0.359; comparing to standard samples (0.194~0.374), the result locates in a reasonable range. As to the comparison with the hurst coefficient of soot aggregates from different diesel cars, we found that with the increases of exhaust, the hurst coefficient would be lowered. In contrast, with the increases of the age of the diesel car, the hurst coefficient would be enhanced. Moreover, with the increases of the mileage of the diesel car, it was shown that the hurst coefficient did not have a significant difference.
In addition, the morphology of the particles emitting from the steel-making were complicated, and they appeared in the form of mineralogy. With the same steps, the hurst coefficient of the steel-making aggregates which we established fell in about 0.469~0.633 (2×104 magnification), and the fractal dimension was about 1.449.
The chemical elements of the single particle were analyzed by EDS. We found that with the larger size of the diesel soot aggregates, the carbon contents were high. This result indicated that the carbon was the major element in all of the chemical elements. Besides, we also discovered other heavy metal elements, such as Fe, Zn, Mn and Cr. The steel-making aggregates contained many elements(C, Na, S, Fe, Zn, Mn, Mg, Cr, Al, etc). According to the classification of weight percentage, the aggregates are mainly composed of Fe and Zn.
The contribution of this work could set up the characteristic of the single particles of two different pollution source, and it could be a database of comparison.

Keyword: single particle, diesel car, steel-making, fractal dimension, chemical analysis

並列關鍵字

single particle ； diesel car ； steel-making ； fractal dimension ； chemical analysis

參考文獻

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