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芬頓試劑

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芬頓試劑(英語:Fenton’s reagent)是一種含有過氧化氫H2O2亞鐵離子 Fe2+(作催化劑,通常是硫酸亞鐵)的溶液。芬頓試劑被用於氧化有機污染物或廢水,是高級氧化技術英語Advanced oxidation process(AOPs)中常用的方法,其對有機廢水中的三氯乙烯(TCE)和四氯乙烯(PCE)等有機物的降解效果明顯。芬頓試劑是由H. J. H. Fenton英語Henry John Horstman Fenton在1894年發現的。[1][2][3]

機理

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芬頓試劑的氧化性來源於過氧化氫在Fe2+ 催化下產生的羥基自由基 ·OH [4],首先亞鐵離子被過氧化氫氧化為鐵離子,在此過程中產生羥基自由基和氫氧根離子,而後鐵離子被另一個過氧化氫分子還原為亞鐵離子,產生過氧化氫自由基和氫離子,反應總和為亞鐵離子催化過氧化氫歧化為兩種自由基。

Fe2+ + H2O2 → Fe3+ + HO + OH 1
Fe3+ + H2O2 → Fe2+ + HO2 + H+ 2
2 H2O2 → HO + HO2 + H2O 1+2

此過程產生的自由基有著較高的氧化還原電位,是一種非選擇性強氧化劑[5],芬頓試劑與有機物的氧化反應迅速且放出大量熱,主要氧化產物為二氧化碳。反應(1)的機理由哈伯與韋斯在1932年提出,並囊括於哈伯 - 韋斯反應之中[6]

硫酸亞鐵是最常用的鐵催化劑,對於亞鐵離子氧化後還原重新切入催化循環的機制尚未有共識。Yamazaki等人報道利用順磁共振(ESR)方法以5,5-二甲基吡咯啉-1-氯氧化物(DMPO)作為自由基捕獲劑分析芬頓反應的機理[7],據稱反應是亞鐵離子被過氧化氫氧化成三價鐵後,由Fe2+和Fe3+共同催化產生羥基自由基的過程,且有部分鐵被氧化為Fe(IV)價態。也有研究認為芬頓反應中除了產生羥基自由基外,也有高價鐵中間體產生,並且在有機物的氧化過程中是Fe=O2+起主導作用[8]

影響因素

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對於芬頓反應的速率(尤其是對光芬頓反應而言),pH是關鍵因素之一。在低pH值時,Fe2+水合物會與HO發生絡合,降低氧化效率[9],且較低pH值時體系中的多餘質子也會與產生的HO發生反應[10]。而pH值偏高時,鐵離子會形成沉澱,使鐵逐漸從催化體系中被去除,從而降低反應速率[11],並且在鹼性條件時H2O2也會自發地分解[12]。較高的pH值也會降低HO的氧化還原電位,從而降低其氧化效果[13][14]

pH對反應速率的影響
低pH 形成[Fe(H2O)6]2+水合物
OH被過量的H+消耗
高pH 降低OH的氧化還原電位
H2O2在鹼性條件下會自發分解
產生Fe(OH)3沉澱

應用

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芬頓試劑被用作污水處理試劑[11][15],芬頓試劑在化學反應中可用作羥基供體或氧化劑,如[16]

芬頓反應在生物化學中有著不同的應用方法,通過在體內細胞中鐵的反應產生或消除自由基,雖然臨床上的用途和重要性尚不明確,但也是活動性感染時避免補鐵的可行方法之一,或是其他任何由鐵介導的感染[19]

拓展閱讀

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外部連結

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參考文獻

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  1. ^ Koppenol, W. H. The centennial of the Fenton reaction. Free Radical Biology and Medicine. 1 December 1993, 15 (6): 645–651. PMID 8138191. doi:10.1016/0891-5849(93)90168-t. 
  2. ^ Fenton, H. J. H. Oxidation of tartaric acid in presence of iron. Journal of the Chemical Society, Transactions. 1894, 65 (65): 899–911. doi:10.1039/ct8946500899. 
  3. ^ Hayyan, M.; Hashim, M. A.; Al Nashef, I. M. Superoxide ion: Generation and chemical implications. Chemical Reviews. 2016, 116 (5): 3029–3085. PMID 26875845. doi:10.1021/acs.chemrev.5b00407. 
  4. ^ Shuangqin, Chen; Mai, Li; Qingmin, Ji; Tao, Feng; Si, Lan; KeFu, Yao. Effect of the chloride ion on advanced oxidation processes catalyzed by Fe-based metallic glass for wastewater treatment. Journal of Materials Science & Technology. 2022, 117 (22): 49–58. 
  5. ^ Cai, Q.Q.; Jothinathan, L.; Deng, S.H.; Ong, S.L.; Ng, H.Y.; Hu, J.Y. Fenton- and ozone-based AOP processes for industrial effluent treatment. Advanced Oxidation Processes for Effluent Treatment Plants. 2021: 199–254. ISBN 978-0-12-821011-6. S2CID 224976088. doi:10.1016/b978-0-12-821011-6.00011-6. 
  6. ^ Haber, F.; Weiss, J. Über die katalyse des hydroperoxydes [On the catalysis of hydroperoxides]. Naturwissenschaften. 1932, 20 (51): 948–950. Bibcode:1932NW.....20..948H. S2CID 40200383. doi:10.1007/BF01504715. 
  7. ^ Isao Yamazaki; Lawrence H Piette. ESR Spin-trapping Studies on the Reaction of Fe2+ Ions with H2O2-reactive Species in Oxygen Toxicity in Biology. The journal of Biological Chemistry. 1990, 265 (23): 13589–13594. 
  8. ^ Hage John P; Llobet Antoni; Sawyer Donald T. Aromatic Hydroxylation by Fenton Reagents {Reactive Intermediate [Lx+Fe][OOH(BH+)], not Free Hydroxyl Radical (HO•)}. Bioorganic & Medicinal Chemistry. 1995, (3): 1383–1388. 
  9. ^ Xu, Xiang-Rong; Li, Xiao-Yan; Li, Xiang-Zhong; Li, Hua-Bin. Degradation of melatonin by UV, UV/H2O2, Fe2+/H2O2 and UV/Fe2+/H2O2 processes. Separation and Purification Technology. 5 August 2009, 68 (2): 261–266. doi:10.1016/j.seppur.2009.05.013. 
  10. ^ Tang, W. Z.; Huang, C. P. 2,4-Dichlorophenol Oxidation Kinetics by Fenton's Reagent. Environmental Technology. 1 December 1996, 17 (12): 1371–1378. doi:10.1080/09593330.1996.9618465. 
  11. ^ 11.0 11.1 Cai, Q. Q.; Lee, B. C. Y.; Ong, S. L.; Hu, J. Y. Fluidized-bed Fenton technologies for recalcitrant industrial wastewater treatment–Recent advances, challenges and perspective. Water Research. 15 February 2021, 190: 116692. PMID 33279748. S2CID 227523802. doi:10.1016/j.watres.2020.116692. 
  12. ^ Szpyrkowicz, Lidia; Juzzolino, Claudia; Kaul, Santosh N. A Comparative study on oxidation of disperse dyes by electrochemical process, ozone, hypochlorite and fenton reagent. Water Research. 1 June 2001, 35 (9): 2129–2136. PMID 11358291. doi:10.1016/s0043-1354(00)00487-5. 
  13. ^ Velichkova, Filipa; Delmas, Henri; Julcour, Carine; Koumanova, Bogdana. Heterogeneous fenton and photo-fenton oxidation for paracetamol removal using iron containing ZSM-5 zeolite as catalyst (PDF). AIChE Journal. 2017, 63 (2): 669–679 [2022-08-26]. doi:10.1002/aic.15369. (原始內容存檔 (PDF)於2022-02-27). 
  14. ^ Cai, Qinqing; Lee, Brandon Chuan Yee; Ong, Say Leong; Hu, Jiangyong. Application of a Multiobjective Artificial Neural Network (ANN) in Industrial Reverse Osmosis Concentrate Treatment with a Fluidized Bed Fenton Process: Performance Prediction and Process Optimization. ACS ES&T Water. 9 April 2021, 1 (4): 847–858. S2CID 234110033. doi:10.1021/acsestwater.0c00192. 
  15. ^ Chen, Yan-Jhang; Fan, Tang-Yu; Wang, Li-Pang; Cheng, Ta-Wui; Chen, Shiao-Shing; Yuan, Min-Hao; Cheng, Shikun. Application of Fenton Method for the Removal of Organic Matter in Sewage Sludge at Room Temperature. Sustainability. 2020-02-18, 12 (4): 1518. ISSN 2071-1050. doi:10.3390/su12041518. 
  16. ^ Fenton’s Reaction - Reaction Details, Reagent, Applications, FAQs. BYJUS. [2022-07-25]. (原始內容存檔於2022-07-25) (美國英語). 
  17. ^ Brömme, H. J.; Mörke, W.; Peschke, E. Transformation of barbituric acid into alloxan by hydroxyl radicals: interaction with melatonin and with other hydroxyl radical scavengers. Journal of Pineal Research. November 2002, 33 (4): 239–247. PMID 12390507. S2CID 30242100. doi:10.1034/j.1600-079X.2002.02936.x. 
  18. ^ Jenner, E. L. (1973). "α,α,α′,α′-Tetramethyltetramethylene glycol". Org. Synth.; Coll. Vol. 5: 1026. 
  19. ^ Lapointe, Marc. Iron supplementation in the intensive care unit: when, how much, and by what route?. Critical Care. 14 June 2004, 8 (2): S37–41. PMC 3226152可免費查閱. PMID 15196322. doi:10.1186/cc2825.