利用零價鐵結合氧化劑(H2O2/Na2S2O8)程序處理非離子界面活性劑之研究

Removal of non-ionic surfactant by fluidized zero valent iron with oxidant(H2O2/Na2S2O8) processes.

邱煌銘(Huang-Ming Chiu)

指導教授 ： 陳孝行

國立臺北科技大學/工程學院/環境工程與管理研究所/碩士(2009年)

摘要

在產業界使用之非離子界面活性劑中使用最廣泛者為壬基苯酚聚乙氧基醇(NPnEO)，且為環境荷爾蒙壬基苯酚(nonylphenol, NP)之主要前驅物，少量的NP便足以影響生物生殖與生理等現象，將使動物雌性化，而在一般生物處理程序下皆處理時間長及去除效率有限等限制，因此，本研究嘗試利用零價鐵及結合氧化劑(H2O2/Na2S2O8)程序運用處理於NPnEO，藉由零價鐵之經濟性及自由基反應快速與高氧化能力使NPnEO可更有效地處理。
本研究利用零價鐵結合氧化劑處理NPnEO，主要分為兩部分，以零價鐵流體化床及以其結合兩種氧化劑(H2O2/Na2S2O8)程序處理NPnEO廢水，主要控制因子則包含水力停留時間、pH值、溶氧及氧化劑劑量，分析出流水之NPnEO濃度、TOC及其他因子的變化，並探討其反應速率常數及反應機制。以零價鐵流體化床程序處理NPnEO廢水階段，當反應pH值為1.5時，水力停留時間3.0分鐘，反應操作2小時後可達穩定，NPnEO、TOC去除率分別為12.5％、9.1％，其反應速率常數為0.048 min-1，當曝入純氧提高溶氧時，在反應pH值3.0，水力停留時間3.0分鐘，NPnEO、TOC去除率從未曝氣之為6.8%、3.6%提升至31%及19.6%，而曝氮氣除去溶氧則使去除率接近於零。
以零價鐵流體化床結合兩種氧化劑程序處理NPnEO廢水時，當氧化劑濃度為23.6 mM時，在結合過氧化氫部份，反應pH值設為4.0、水力停留時間為1.5分鐘時，NPnEO、TOC去除率分別為99%、54%，提升氧化劑濃度對於去除效率有不升反降的現象。在結合過硫酸鹽部份，反應pH值為4.5時，水力停留時間以較低之0.75分鐘為最佳，降解效果之NPnEO、TOC去除率分別為77%、41%，且降解效率隨氧化劑濃度上升有增加的現象。在兩程序之比較上，降解效率明顯以過氧化氫優於過硫酸鹽，在氧化劑對NP危害性去除利用率之評估下，過氧化氫平均值1.3%亦高於過硫酸鹽之0.7%，在pH值控制的穩定性則以過硫酸鹽較佳。
在各項反應機制的探討上，零價鐵流體化系統中是以零價鐵使溶氧反應產生過氧化氫作為氫氧化自由基的來源，而在結合氧化劑程序中是扮演犧牲部份氧化劑作為快速生成亞鐵以供應反應之用。在微胞的影響效應上，NPnEO微胞的臨界濃度約在40 mg/L，且微胞的形成將對Fenton法在NPnEO濃度的降解上造成障礙。

關鍵字

非離子界面活性劑 ； NPnEO ； 零價鐵 ； 過氧化氫 ； 過硫酸鹽、流體化床

並列摘要

NPnEO is a major ingredient in nonionic surfactant and precursor of nonylphenol(NP) which is an endocrine-disrupting chemical affecting human endocrine system, including varieties of glands and hormones. Since NPnEO has micelle property at high concentration, typical biological treatment is not effective. Besides, the degradation of the phenolic structure by Fenton process along is also difficult due to that its micelle property where the non-polar/hydrophobic property of phenol is wrapped by the long-chained polar/hydrophilic ethylene oxide.
This study contains two stages of experimentation. First of all, the fluidized ZVI process was used to treat NPnEO. Secondly, two oxidant (H2O2/Na2S2O8) was combined with the fluidized ZVI process. The water samples containing NPnEO 200mg/L was treated at various pH, hydraulic retention time, dissolved oxygen(DO) and the oxidant dosage. In the first stage, the removal efficiency and reaction rate of NPnEO were highest in un-aeration condition, when the pH value was 1.5, and the HRT was 3.0 minutes. NPnEO and TOC removal efficiency can reach 12.5% and 9.1%, respectively, and the reaction rate of NPnEO was 0.048 min-1 and was increased with increase of DO.
The second stage of experimentation was ZVI fluidized bed combined the oxidants(H2O2 and Na2S2O8) process, It included ZVI-H2O2 system and ZVI-Na2S2O8 system. In ZVI-H2O2 system, when the oxidant concentration was 23.6 mM, the pH value was 4.0, and HRT was 1.5 minutes, the result shows that the NPnEO and TOC removal efficiency was 99% and 54%, respectively. The removal efficiency was increased with oxidant dosage, but that was reduced when oxidant dosage was in excess of 23.6mM. In the ZVI-Na2S2O8 system, the optimum operating conditions for pH value and HRT were 4.5 and 0.75 minutes, the removal was also increased with oxidant of Na2S2O8 dosage in the system. To compare the ZVI-H2O2 system and ZVI-Na2S2O8 system, the removal efficiency of ZVI-H2O2 was better than that of ZVI/Na2S2O8 on the same pH value, HRT and oxidant dosage, but the ZVI-Na2S2O8 was more stable with constant pH.

並列關鍵字

Nonionic surfactant ； NPnEO ； zero valent iron ； hydrogen peroxide ； persulfate ； fluidized bed

參考文獻

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