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年度	102	專案性質	實驗性質
專案類別	研究專案	研究主題	整治
申請機構	元智大學	申請系所	化學工程與材料科學學系
專案主持人	林錕松	職等/職稱	教授
專案中文名稱	利用表面改質奈米零價鐵還原降解高能火炸藥TNT、RDX及HMX污染場址整治工程技術評估及測試
中文關鍵字	奈米零價鐵；高能火炸藥；還原降解；現址污染整治技術
專案英文名稱	Development of Reductive Decomposition for TNT/RDX/HMX High-energy Explosives contaminated Groundwater and Its In-Situ Remediation Technology Evaluation
英文關鍵字	"Zero-valent iron nanoparticle；High-explosives；Reductive degradation；In-situ contamination remediation
執行金額
執行期間	2012/12/10 至 2013/12/9
計畫中文摘要	由於台灣地小人稠，高能火炸藥(TNT、RDX 及 HMX)在製程中之廢水極可能 排放於周遭環境中，常常造成土壤及地下水的污染，此污染物對人體及生態具高 毒性且難以從環境中降解去除，故環保且有效的處理受高能火炸藥污染的土壤及 水體的技術，即成為現今技術研發之重要課題。因此，本研究計畫之主要目的在 利用化學還原法製備奈米零價鐵顆粒(ZVINs)，加以表面改質後，應用於處理因高 能火炸藥三硝基甲苯(TNT)、海掃更(RDX)及奧特更(HMX)污染地下水體；另外， 本研究計畫更利用奈米零價鐵觸媒對火炸藥污染去除，並以台中某軍事污染場址 進行初步現址整治測試，提供工程技術放大及環保經濟效益上有效之處理技術與 研究成果。本計畫內容可分為三大部分：第一部分將藉由自行合成及表面改質 ZVINs 微粒，並以精密儀器測定奈米 Fe(0)之晶相、價數表面積及孔洞分析及與火 炸藥反應後之表面分析及金屬氧化物種類，探討 Fe(0)還原火炸藥之途徑；第二部 份以液相層析串聯質譜儀(LC/MS/MS)，探討受污染地下水體中高能火炸藥之降解 效率、反應動力參數、熱力學模式及反應途徑；亦利用貴重精密儀器，例如：FE-SEM、 XRD、XPS、TEM、BET 比表面積測定儀(ASAP)及同步輻射(XANES/EXAFS)分析， 鑑定ZVINs反應前後結構特性及產物之差異性，進而深入瞭解表面改質前後ZVINs 還原降解反應高能火炸藥之機制及途徑，並探討處理含火炸藥地下水之界面化學 及反應機制，以利提升去除含火炸藥污染之地下水之效果；第三部份則進行 ZVINs 批式、管柱測試及模擬現址砂箱反應牆處理系統，並以台中某軍事污染場址進行 ZVINs 還原降解反應高能火炸藥之初步現址整治測試，以利後續經濟效益評估或 基本工程放大設計之參考。本研究計畫之相關研發成果說明如下： 1. XRD 圖譜顯示自行合成之奈米零價鐵粉在 2θ=44.59 處有強訊號，並且在 FE-SEM圖中為粒徑10-50 nm之球形顆粒，經由BET量測其比表面積為42.557 m 2 /g 總孔體積為 0.232 cm3 /g，利用 XPS 分析表面 Fe/O 之比例為 0.54，並且 含有 FeO, Fe3O4, α-Fe2O3, FeSO4 ,FeB ,B2O3 等在惰化之零價鐵粉表面； 2. 已完整建立PEG改質奈米零價鐵粉之最佳表面改質與粉體分散技術；實驗中， 由穿透式電子顯微鏡(TEM)分析可明顯發現，在奈米零價鐵微粒表面上有 200 nm 之外層為片狀 PEG 高分子膜，分散效果佳且置於水中 24 h 內尚未完全沉 澱；而使用油酸之改質處理，其在表面上有 5-10 nm 之分子膜之包覆，分散效 果較差，置於水相中 6 h 後仍會發生聚集無法分散。 3. 新鮮經惰化之奈米零價鐵粉由 BET 量測其比表面積為 43.65 m2 g -1。降解研究 中，以 0.1 g 之 nano-Fe(0)降解 3 種高能火炸藥水溶液，實驗結果顯示在室溫 下(25 ± 1℃)於 1 h 內可完全降解 90 ppm 之 TNT、35 ppm 之 RDX 及 5 ppm 之 HMX。在動力學研究中，將 nano-Fe(0)降解三種不同濃度高能火炸藥實驗結 果代入簡化的 Langmuir-Hinshelwood 動力學模式 ln(C0/Ca) = kt 計算得到 R 2 > 0.995，其降解反應為一階反應。在熱力學模式研究中，則是以三種不同的高 能火炸藥於 25 及 35℃的溫度下進行實驗，並以 Arrhenius equation 計算其活 化能，得到 TNT、RDX 及 HMX 的活化能分別為 9.6、10.2 及 12.2 kcal/mol。 4. 在利用奈米零價鐵粉降解三種不同濃度高能火炸藥反應前中後之產物分析， 由 FE-SEM 及 TEM 分析發現奈米零價鐵顆粒數量減少及片狀產物的增加的趨 勢，再以 XPS 分析顯示其表面具有 Fe、FeO、Fe3O4 及 Fe2O3 等四種不同的氧 化物，且其反應鐵化合物之趨勢為 Fe(0) → FeO → Fe3O4 → Fe2O3。 5. 在利用奈米零價鐵粉降解高能火炸藥之反應途徑研究中，由 LC/MS/MS 及 GC/MS 分析結果顯示高能火炸藥反應反應途徑是第一步為 NO2 官能基團被還 原取代成 NO 官能基團，第二步為 NO 官能基團被還原取代成 NH2 官能基團 後，導致結構不穩定而水解開環。 6. 在利用奈米零價鐵粉降解高能火炸藥反應後最終產物，以 XANES 分析結果顯 示，其反曲點最接近 Fe3O4，且藉由 EXAFS 分析其中心 Fe 原子配位數接近 4， 表示結構可能是八面體中平面四邊形結構；Fe-O 的鍵距約為 1.94 ± 0.01 Å ， 再以 XRD 分析晶形結構，其圖譜結果發現相似 Fe3O4。 7. 管柱實驗顯示，在奈米零價鐵需要量的試驗，若要得到比較快速的成果，可 選擇 2 g/kg 的使用量，但由於零價鐵本身特性屬於表面有孔洞，污染物在進 入孔洞時會產生反應，使表面產生氧化鐵層，導致傳導速率下降，故反應速 率會大於質傳速率，若使用 1 g/kg 的濃度其去除污染物的能力還是能夠達到 80%以上，但相對時間較長。使用管柱來處理受火炸藥污染土壤的實驗中，奈 米零價鐵處理受 TNT 污染的土壤去除率約為 40%，而奈米零價鐵處理受 RDX 污染的土壤去除率約為 50%，推測為缺少燒杯中的攪拌，未能完全與奈米零價鐵反應，僅依賴水流之淋洗難以將土壤中污染物與奈米零價鐵接觸，亦是 火炸藥容易被土壤吸附，地下水淋洗時不易攜帶，故處理能力有限，上中下 三層處理後污染濃度差只有 10%不到也說明此點。砂箱試驗可得知土壤中 TNT 的濃度在前 3 次循環有明顯的下降，而水中的濃度並沒有明顯上升，推 斷是因為土壤中一部分的 TNT 被水淋洗並與奈米零價鐵牆反應，才會造成土 壤中的濃度降低而水中的濃度無明顯提升，而差距部分為奈米零價鐵反應牆 之反應能力，而進行到第 4 次循環之後，土壤中的濃度已經停止下降，推測 與土壤吸附有關，土壤中有機質含量高其陽離子交換能力也較好，故相對不 容易被淋洗，其土壤中的 TNT 濃度不容易再下降，與管柱實驗結果相符。
計畫英文摘要	In the recent years, soil, wastewater and groundwater are polluted by explosives-contaminated wastewaters discharged from military factory worldwide. These high-explosives are toxic to human beings/ecosystems and very difficult to be removed from the environment. Therefore, a highly efficient and clean method has been already developed utilizing zero-valent iron nanoparticles (ZVINs) to reduce the explosives-contaminated soil and groundwater. In this research, LC/MS/MS have been used to determine the efficiency of degradation, kinetic model, thermal model, activation energy, and reaction pathways for ZVINs degradation of high-explosives. Nanophase zero-valent iron powders have been surface-modified and then enhanced the efficiency of reduction by adding oleic acid/polyethylene glycol (PEG) nanofilms. The lab-scale batch ZVINs reactor, continuous-flow column ZVINs reductive system, and simulated sand-boxed type permeable reactive ZVINs barrier were also conducted. Moreover, the properties of ZVINs before or after degradation were also analyzed. The morphology and crystallinity of ZVINs, fine structures, oxidation states of metals in ZVINs have been investigated with FE-SEM/EDS, XRD, XPS, TEM, ASAP, and EXAFS/XANES techniques. By these experimental data, optimal operations, conversion, mechanism, basic engineering design of abatement technologies, and economic estimation of a lab-scale reductive ZVINs column reactor of contaminated soils were further performed and tested from Tai-Chung County military contaminated area. Therefore, the proposed research has been finished and the results were shown as following. 1. ZVINs with a strong characteristic peak at 2θ = 44.6o were investigated by XRD patterns. By FE-SEM analyses, spherical ZVINs with a diameter of 10-50 nm were found. The specific surface area and pore volume of ZVINs measured by BET isotherms are 42.557 m2 /g and 0.232 cm3 /g, respectively. From XPS spectra, the proportion of Fe/O is 0.54 on ZVINs surface including the main species of FeO, Fe3O4, α-Fe2O3, FeSO4, FeB, and B2O3. 2. By using the surface coating of oleic acid (OA), ZVINs were in the chain form of spherical particle with 5-7 nm outside nanofilms measured by TEM. Similarly, ZVINs coated with polyethylene glycol (PEG) in the form of spheical particle with 200 nm, outside mixing layer of 50 nm for PEG and iron oxide nanofilms were found. The dispersion stability of PEG/ZVINs (<24 h) is higher than that of QA/ZVINs (<6 h). 3. In the degrading experiments, 90 ppm of TNT, 35 ppm of RDX, and 5 ppm of HMX at room temperature (25 ± 1℃) were degraded completely with 0.1 g ZVINs within 1 h. The experimental results were simulated using Langmuir-Hinshelwood equation (ln(C0/Ca) = kt) and the r 2 were all approached to 0.995. However, the degradation statistics corresponded to the pseudo first order kinetics. The thermodynamics study was carried on three different high-explosives under 25-35 ℃ and the activation energies of TNT, RDX, and HMX were calculated of 9.6, 10.3, and 12.2 kcal/mol by Arrhenius equation, respectively; 4. In reductive degradation of TNT/RDX/HMX high-energy explosives onto ZVINs, the amount of ZVINs were decreased and converted to sheet-typed ZVINs were observed. Moreover, the surface composition of Fe, FeO, Fe3O4, and Fe2O3 was measured by XPS and the crystalline structures were consistent with the data of Fe3O4 and Fe2O3 identified by XRD patterns. 5. In the investigation of degradation pathways/mechanisms for TNT/RDX/HMX high-energy explosives onto ZVINs, the intermediates of TNT/RDX/HMX degradation were identified by LC/MS/MS. The substitution of high-explosives was reduced by different quantities of nitroso group into hydroxylamine. The ring structure of the explosives became destabilized when nitroso group was further reduced to a hydroxylamine group resulting into ring cleavage by a hydrolysis route eventually. 6. The valence of ZVINs after degradation of TNT/RDX/HMX high-energy explosives onto ZVINs was 8/3 identified by XANES technique. The coordination numbers of Fe atom in ZVINs were close to 4 and the bond distance of Fe-O was 1.94 ± 0.01 Å determined by EXAFS spectra. 7. In column tests, the amout of ZVINs of 2 g/kg is good enough for the prediction of TNT/RDX/HMX contaminants degradation onto ZVINs. Since the pore structure of ZVINs that reductive degradation of explosives was occurred on the surface, it may cause the higher mass transfer resisitance control of iron oxides inside the pore sutructures compared with that of reaction rate resisitance control. Based on using 1 g/kg of ZVINs, the longer resistance time of explosives degradation efficiency approached 80%. The degradation efficiencies of TNT, RDX, and HMX onto ZVINs for degradation tests were 40, 50, and 45%, respectively. The results were possibly affected the that mixing problems and adsorption capacity of soils with explosives. In addition, the washing ability of flowing water for explosives contaminated soils was more difficult than that of lab-scale tests. The derivation of the three layers of contaminated soils was only 10% that may be confirmed and is consistent with the results. Moreover, the TNT concentrations in soils of the first three-cycle column experiments were significantly decreased and slightly increased in groundwaters. It may be affected by the reductive degradation ability of explosives onto ZVINs for washed contaminated soils. The concentration of contaminated soil was stopped decreasing in the fourth cycle that may be casued by soil adsorption or higher organic cation exchange capacity (CEC) of soils. The result was also consistent with that of column tests.