Removal of Pentachlorophenol in Groundwater by E-Fenton Coupled with Permeable Reactive Barriers

本研究應用近年來大為發展的地下水現地整治技術：零價鐵透水性反應牆，其經濟、操作簡單，藉由所填充的零價鐵，可將高氯量碳氫化合物完全破壞去除或轉化為較低氯量之碳氫化合物，並結合近年來熱門的廢水處理技術E-Fenton法，其藉在陰極還原成過氧化氫，立即與溶液中的亞鐵離子催化成氫氧自由基，形成與傳統Fenton法相同的效果，去除地下水中的五氯酚。 本研究之目的在於評估透水性反應牆對五氯酚之脫氯效果，以及E-Fenton反應對五氯酚進一步之破壞去除，並且利用循環批次實驗探討系統處理的最佳條件及對五氯酚的處理機制，最後再進行實驗數據之整理。 由背景實驗結果可發現，過氧化氫生成實驗中，空氣流量為0.7 L/min時，有最大的過氧化氫生成效率5.2×E-3 mg/min。當五氯酚的濃度為5mg/L，pH= 4，水流方向為陰極流向陽極，反應牆中填入零價鐵/石英砂=1/60(g/g)，提供電流密度為0.75mA/cm2，迴流量為20 mL/min的條件下，去除率可達63%，礦化率可達26%。並且E-Fenton結合反應牆的處理系統，相較於傳統的添加過氧化氫的Fenton反應，明顯的提高去除率及礦化率。但是，在本系統中亞鐵離子的濃度過高，若要提升系統效能，可提高過氧化氫的生成量。Permeabe reactive barrier(PRB) embedded with zero-valent iron(Fe0) has been used as the remediation technology of ground water. The method develops greatly in the recent years for the dechlorination or completely destroy of pentachlorophenol(PCP). The E-Fenton method is a popular waste water treatment technique that could produce hydrogen peroxide by cathode, which then react with ferrous iron (called Fenton processes). Fenton reaction could degrade PCP by oxidation. The purpose of this study is to estimate the removal of PCP by E-Fenton coupled with PRB in a recirculating batch experiment, and to gain the best condition for this system and the removal mechanism of PCP. Based on the results of background experiment, 0.7 L/min air applying could produce 5.210-3 mg/min hydrogen peroxide. PCP of 5 mg/L could be degraded for 63%, and mineralized for 26% when initial pH is 4, flow direction is cathode to anode, PRB consists of Fe0/quartz sand(QS)=1/60(g/g), current density is 0.75mA/cm2, and flow rate is 20 mL/min. The removal efficiency and mineralization of E-Fenton is better than those of traditional Fenton process. Because of the concentration of Fe2+ is too high in this system, when the efficiency increased proportionally, the producing ratio of hydrogen peroxide increased.摘要.....................................................I ABSTRACT.............................................. III 目錄.....................................................V 圖目錄.................................................VII 表目錄................................................ IX 第一章 前言............................................. 1 1-1 研究緣起............................................ 1 1-2 研究目的............................................ 2 第二章 文獻回顧........................................ 3 2-1 五氯酚的特性、來源及污染現況........................ 3 2-1-1 五氯酚之特性...................................... 3 2-1-2 五氯酚化合物之來源及用途......................... 6 2-1-3 五氯酚之污染現況.................................. 8 2-1-4 五氯酚的毒性及其危害性.......................... 11 2-1-5 五氯酚相關法規.................................. 13 2-1-6 五氯酚在環境中的宿命和可能降解途徑.............. 15 2-1-7 五氯酚污染之整治技術............................. 16 2-2 透水性反應牆....................................... 20 2-2-1 透水性反應牆之處理機制.......................... 21 2-2-2 現地應用情況.................................... 23 2-3 Fenton 法.......................................... 26 2-4 電解氧化法........................................ 29 2-4-1 直接電解氧化法................................... 29 2-4-2 E-Fenton 法................................... 30 2-5 影響 E-Fenton 法的因素............................. 34 2-5-1 溶液 pH 值.................................... 34 2-5-2 過氧化氫濃度..................................... 36 2-5-3 亞鐵離子濃度.................................... 36 2-5-4 溫度............................................ 37 2-5-5 導電度.......................................... 37 2-5-6 電流密度........................................ 38 2-5-7 不同亞鐵離子與過氧化氫濃度比.................... 38 2-5-8 氯酚類化合物種類及初始濃度...................... 39 2-6 E-Fenton 與透水性反應牆之組合技術.................. 40 第三章 實驗方法........................................ 41 3-1 研究流程.......................................... 41 3-2 實驗裝置.......................................... 43 3-3 實驗藥品及配置.................................... 45 3-3-1 實驗藥品........................................ 45 3-3-2 實驗藥品配製.................................... 46 3-4 實驗分析方法...................................... 47 3-4-1 水質參數分析方法................................ 48 3-4-2 五氯酚濃度分析方法.............................. 48 3-4-3 亞鐵離子分析方法.................................49 3-4-4 過氧化氫分析方法................................. 49 3-4-4-1 高濃度過氧化氫分析方法......................... 49 3-4-4-2 低濃度過氧化氫分析方法......................... 50 3-4-5 總有機碳分析方法................................ 50 第四章 結果與討........................................ 51 4-1 基礎實驗.......................................... 51 4-1-1 檢量線建立...................................... 51 4-1-2 五氯酚萃取回收率測試............................. 51 4-1-3 石英砂粒徑分析................................... 23 4-2 背景實驗.......................................... 54 4-2-1 過氧化氫生成實驗................................ 54 4-2-2 五氯酚曝氣實驗.................................. 55 4-2-3 不同 pH 對五氯酚殘餘率之影響................... 56 4-2-4 不同流向對五氯酚殘餘率之影響.................... 58 4-2-5 PRB、E-H2O2及 E-Fenton 之比較................. 61 4-3 不同電流密度對五氯酚的影響........................ 64 4-4 不同五氯酚濃度對 E-Fenton 系統的影響.............. 67 4-5 不同零價鐵量對 E-Fenton 系統的影響................ 70 4-6 傳統 Fenton 與 E-Fenton 的比較.................... 73 第五章 結論與建議..................................... 77 5-1 結論.............................................. 77 5-2 建議...............................................78 参考文獻............................................... 79 附錄................................................... 9