| 摘要: | 傳統Fenton法是一種高級化學氧化程序，以過氧化氫為氧化劑，亞鐵離子為催化劑，產生氫氧自由基以分解有機物，於廢水高級處理的應用上具有高效率、低操作費用等優點，但因會產生大量的化學污泥，而成為應用時的最大缺點。針對Fenton法污泥產量太多的缺點加以改良，利用電場或結晶技術來提升處理效果及降低化學污泥產量。本研究將採用電-Fenton法及流體化床-Fenton法處理於苯胺合成廢水，探討其兩者反應程序對苯胺去除效能的差異程度。
結果發現，苯胺的分解與起始pH值、亞鐵離子劑量、過氧化氫劑量有關，隨著亞鐵離子濃度與過氧化氫濃度增加，苯胺氧化速率增加。
動力探討方面，使用兩階段反應模式表示，本研究採用兩種Fenton程序處理苯胺廢水，起始pH=2.6 ~ 4範圍間時，在Electro-Fenton法中，求得苯胺平均氧化速率與反應常數K值範圍為0.40×10-3 M min-1 ~3.06×10-3 M min-1與0.21 min-1 ~ 0.72 min-1；FB-Fenton法中，苯胺平均氧化速率與反應常數K值範圍為為0.72 M min-1 ~ 2.47×10-3 M min-1與0.06 min-1 ~ 0.36 min-1。當pH＝3.2時，求得最佳氧化速率。隨著亞鐵離子濃度與過氧化氫濃度增加時，苯胺降解平均氧化速率與反應常數K值增加；苯胺濃度增加，則苯胺降解平均氧化速率與反應常數K值下降。
Electro-Fenton法與FB-Fenton法之特性發現，陰離子對不同Fenton程序影響中，對於不同Fenton法皆會有抑制的情形，在添加磷酸二氫根抑制情形較明顯。改變過氧化氫加藥方式試驗中，二次加藥能增加Electro-Fenton程序氧化苯胺的降解速率；而在FB-Fenton程序中，反應60分鐘後，系統中苯胺的去除率接近，能使礦化效率提升。
比較Electro-Fenton法及FB-Fenton法氧化苯胺，操作條件控制為〔C H NH 〕＝1.0×10-2M,〔Fe2+〕＝1.07×10-3 M,〔H2O2〕＝0.058 M,〔SiO2〕＝100g, current＝4A, pH＝3.2，反應60分鐘後，以Electro－Fenton程序處理苯胺，系統中苯胺去除率達95﹪；FB-Fenton程序處理苯胺，系統中苯胺去除率達83﹪，可知以Electro－Fenton程序氧化苯胺去除效率高於FB-Fenton程序。
Fenton process is one of advanced oxidation processes. It uses hydrogen peroxide and ferrous ions to produce hydroxyl radicals that can oxidize various types of pollutants. Fenton process take advantage of the high efficiency and low operational cost. However, the primary disadvantage of this process is the generation of high volume of iron sludge. Previous studies showed that applying electric current or crystallization technology effectively reduces the iron sludge generation.
Therefore, this study applied Electro-Fenton and Fluidized bed (FB) Fenton processes to treat the synthetic wastewater for comparing the difference between these two systems.
Results show that initial pH, ferrous ion, hydrogen peroxide and aniline concentration would affect the degradation of aniline. The reaction rate increased with increasing ferrous ion and hydrogen peroxide concentration. Two-stage model is applied to describe the reaction kinetics. In this study, when initial pH=2.6~3.2, average oxidation rate of aniline were 0.40~ 3.06(×10-3 M min-1) and K for aniline were 0.21~ 0.72 (min-1) for electro-Fenton process. In FB-Fenton process, average oxidation rate for aniline were 0.72~ 2.47(×10-3 M min-1) and K of aniline were 0.06~0.36 (min-1).Reaction rates and removal efficiencies of aniline using different Fenton processes were better at pH 3.2. The average oxidation rate and K increased with increasing ferrous ion and hydrogen peroxide concentration. Average oxidation rate and K decreased with increasing aniline concentration.
Anions suppressed the decomposition of aniline in the following sequence: H2PO4> Cl- for both electro-Fenton and Fluidized bed Fenton processes. Multi-step H2O2 addition did not affect the aniline removal efficiency for Electro-Fenton process. However, one-step H2O2 addition was better than multi-step H2O2 addition for FB-Fenton.
To compare electro-Fenton and FB-Fenton processes, the following operating conditions were used, namely 〔C H NH 〕＝1.0×10-2M,〔Fe2+〕＝1.07×10-3 M,〔H2O2〕＝0.058 M,〔SiO2〕＝100g, current＝4A, pH＝3.2. After 60 min, aniline removal was 95﹪for electro-Fenton process while 83﹪of aniline was removed by FB-Fenton process. Therefore, aniline oxidation efficiency by Electro-Fenton process is better compared with FB-Fenton process. |
