跳到主要內容 :::

年度	103	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	國立中興大學	申請系所	環境工程學系
專案主持人	梁振儒	職等/職稱	教授
專案中文名稱	維生素C還原降解火炸藥污染物-以硝基苯為例之翻土混合工法應用評估
中文關鍵字	環境復育；地下水污染；土壤污染；化學氧化；化學還原
專案英文名稱	Vitamin C reductive degradation of explosive contaminants – evaluation of soil mixing technique using nitrobenzene as a model compound
英文關鍵字	Remediation；Groundwate contamination；Soil contamination；Chemical oxidation；Chemical reduction
執行金額
執行期間	2013/11/25 至 2014/11/24
計畫中文摘要	軍事營區內土壤及地下水遭受火炸藥類物質污染為一常見之環境問 題，此類物質皆屬於硝基芳香族化合物(Nitro aromatic compounds, NACs)， 其苯環上之硝基(-NO2)具+III 之 N 氧化態，因而具有吸收電子之特性，易行 還原降解反應，硝基苯(Nitrobenzene, NB)為 NACs 中結構相對簡單之化合 物。維生素 C (即抗壞血酸, Ascorbic acid, AA)為可釋放兩電子之還原劑，因 此，本研究探討 AA 還原降解 NB 之可行性，並評估反應系統中不同 pH、 NB 濃度、AA 濃度之影響。更進一步，藉由 NB 降解副產物推估整體反應 系統之降解途徑。 由不同 pH 條件下之實驗結果可知，於鹼性(pH >12)之條件下，AA 能有 效還原降解 NB，亦可觀察到亞硝基苯(Nitrosobenzne)、偶氮苯(Azobenzene)、 氧化偶氮苯(Azoxybenzene)及苯胺(Aniline)等副產物之生成及降解，並推估 出 NB 於系統中之反應降解途徑。進一步藉由 NB 及 AA 兩者對反應影響之 關係推估，AA 還原降解 NB 之反應速率式：r = (0.89 ± 0.11) × 10-4 mM1-(a+b) h-1[NB]a = 1.35 ± 0.09[AA]b = 0.89 ± 0.01。於泥水相系統，以 CaO、Ca(OH)2或 1 M NaOH 作為調整反應 pH 之方式，雖然皆能於反應時間 120 小時內，有效將 系統維持在鹼性(pH>11)，但只有添加 1 M NaOH 於 100 mM AA 溶液之組別 能有效還原降解泥水相 NB，並可藉由提高反應水土比(100/100→200/100 ml/g)增加泥水相 NB 去除率(40→80%)。進一步採用攪拌及超音波震盪之方 式模擬翻土混合工法(soil mixing)，皆能有效去除泥水相 NB(去除率約 80-90%)，因此，此研究計畫案成果證實鹼性維生素 C 具有處理火炸藥類物 質污染土壤之潛力。
計畫英文摘要	The soil and groundwater contaminated with explosives in military bases are common environmental concerns. These explosive compounds are clarified as nitro aromatic compounds (NACs), in which structure nitrite ion (NO2 - ) owns a +III oxidation state of the nitrogen atom and tends to gain electrons. Nitrobenzene (NB) is the simplest compound of NACs. Vitamin C (a.k.a. ascorbic acid, AA) is a two-electron reductant. Therefore, the vitamin C reductive degradation of NB was evaluated and the effects of pH, NB concentration, AA concentration were examined. Also, degradation products and pathway were assessed. The experimental results indicated that the degradation of NB (1 mM) by AA (100 mM) is strongly pH dependent. The removal of NB can be reached above 80% at pH 12 and 13. Additionally, nitrosobenzene, azobenzene, azoxybenzene and aniline were detected as major intermediate byproducts and NB degradation pathway was thus proposed. Furthermore, the reaction kinetics were determined and revealed that the reaction rate equation: r = (0.89 ± 0.11) × 10-4 mM1-(a+b) h-1[NB]a = 1.35 ± 0.09[AA]b = 0.89 ± 0.01. In the water-soil slurry system, pH was adjusted to alkaline (pH > 11) condition by adding CaO, Ca(OH)2 or 1 M NaOH. However, even though pH was well maintained at alkaline conditions (pH > 11) within 120 h reaction, only the system of 1 M NaOH with 100 mM AA solution exhibited the ability to degrade NB. Furthermore, the removal of NB can be increased from 40% to 80% by adjusting the ratio of solution/soil from 100/100 to 200/100 ml/g. When using mechanical or ultrasonic soil mixings, the removal of NB can also reach 80-90%. Therefore, this innovative alkaline AA reductive reaction exhibits the potential in degrading explosives contaminated soils.