結合零價鐵與現有處理技術應用於去除地下水中Atrazine :比較各系統不同參數之影響

Zero-valent iron (ZVI) for degradation of atrazine was applied in different treatment process and the results were compared

吳佳鴻(Chung-Hung Wu)

指導教授 ： 李奇旺

淡江大學/工學院/水資源及環境工程學系碩士班/碩士(2006年)

https://doi.org/10.6846/TKU.2006.00007

摘要

文獻雖提及零價鐵處理Atrazine效果相當好，但是所使用之操作條件、結果不盡相同，因此本研究結合零價鐵與現有處理技術去降解Atrazine，比較零價鐵在不同處理系統中之差異。而研究過程中所採用之處理系統有：(1)零價鐵管柱床(2)零價鐵流體化床(3)零價鐵曝氣槽實驗，皆有其優缺點，期望找出最佳條件及解決方式。
實驗過程中發現Atrazine降解過程包含氧化及還原機制。在流體化床及曝氣槽實驗中，由降解Atrazine速率來看，還原機制明顯比氧化機制慢了許多，且會隨pH變化而不同。如實驗結果顯示在pH 3及2時，Atrazine去除效果隨著添加之鐵量增加而提高，可達到70%及90%。然而於pH 4時Atrazine去除效果增加的趨勢並不明顯。原因為鐵反應後產生之氧化物覆蓋於鐵表面，而pH 4之氫離子濃度並無法完全降低氧化物量，因此零價鐵電子傳遞受到影響，使Atrazine降解效果降低，因此建議零價鐵流體化床與曝氣槽系統最佳pH值之選擇為pH 3以下。但是以上所得到之結論並不符合管柱床系統之趨勢，由實驗結果顯示管柱床系統中pH控制於中性時Atrazine降解效果較好，原因為管柱床系統進流水pH值越低，所產生之氧化物越多，使降解Atrazine之效果變差。若於零價鐵系統中添加H2O2，其產生之Fenton反應有效提升Atrazine去除效果，且Atrazine於幾分鐘就可以完全去除。

關鍵字

草脫淨 ； 零價鐵 ； H2O2 ； 流體化床 ； 氧化 ； 還原

並列摘要

Several papers had pointed out zero valent iron could degrade atrazine effectively. However, different operation conditions applied among these studies make the results quite different. In this study, Zero-valent iron (ZVI) for degradation of atrazine was applied in different treatment process and the results were compared. Three treatment systems were studied, including (1) zero valent iron column bed reactor, (2) fluidized zero valent iron reactor, and (3) zero valent iron purging bed reactor. All of them have their inherited advantages and disadvantages which will be elucidated along with the suggestions of best operational conditions for these processes.
Both reductive and oxidative mechanisms are responsible for degradation of atrazine on our experiment. In the fluidized zero valent iron reactor and zero valent iron purging bed reactor, the degradation of atrazine by reductive mechanism is a much slower process than that by oxidative mechanism, and is pH dependent. At pHs of 3 and 2, atrazine degradation efficiency increased with increasing ZVI dosages, up to 70% and 90%. But the increasing trend is not observed for system controlled at pH 4.0. It is due to passive surface coating by corrosion iron products at this pH. The concentration of hydrogen at pH 4 is not enough to reduce the amount of iron corrosion products, which influence transfer of electrons and reduce the effectiveness of atrazine degradation. Therefore, operational pH of under 3 is suggested. But the effect of pH is not the same with that observed in column bed reactor. The effectiveness of atrazine degradation is better when influent pH is controlled at near neutral. When influent pH was controlled at acidic range, more iron corrosion products were produced, decreasing the effectiveness of atrazine degradation. Addition of H2O2 greatly enhanced removal of atrazine through Fenton reaction, and atrazine degradation was completely within the first few minutes of reaction.

並列關鍵字

Atrazine ； zero-valent iron ； H2O2 ； Fluidized bed reactor ； reduction ； oxidative

參考文獻

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Chen, J.-L.,Al-Abed, S.R.,Ryan, J.A.,Li, Z. 2001. Effects of pH on dechlorination of trichloroethylene by zero-valent iron. Journal of Hazardous Materials 83(3), 243-254.

Dombek, T.,Davis, D.,Stine, J.,Klarup, D. 2001. Rapid reductive dechlorination of atrazine by zero-valent iron under acidic conditions. Environmental Pollution 111(1), 21-27.

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