跳到主要內容 :::

年度	112	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	台北醫學大學	申請系所	公共衛生學系
專案主持人	胡景堯	職等/職稱	教授
專案中文名稱	利用土壤中鐵錳礦物現地產生高價鐵錳物種去除地下水中氯酚類污染物
中文關鍵字	鐵錳礦物,高價鐵錳物種,氯酚類污染物
專案英文名稱	In situ generation of high-valence iron-manganese species generated from iron-manganese minerals in the soil to remove chlorophenols in groundwater.
英文關鍵字	Iron and manganese minerals, high-valent iron and manganese species, chlorophenols
執行金額	996,000元
執行期間	2023/12/15 至 2024/11/30
計畫中文摘要	酚及氯酚類化合物是地下水中常見的污染物，添加氧化劑或催化劑對這些污染物進行現地處理是一個較經濟可行的選項。鐵與錳是土壤中常見的元素，他們的高價氧化物(鐵酸根及過錳酸根)能有效去除氯酚類化合物，但是大量添加鐵酸根及過錳酸根卻可能因為反應後的沉澱物堵塞土壤孔隙造成傳輸困難。本研究嘗試利用注入鹼性次氯酸鹽的方式合成高價鐵錳氧化物，可以將鐵錳元素從反應物變成催化劑，不需要持續注入鐵酸根及過錳酸根，以避免形成大量不可溶解的鐵錳沉澱物堵塞土壤孔隙而造成傳輸困難。另外，本研究計畫使用乾冰作為之後的中和緩衝劑。由於土壤地下水系統為一種半封閉的環境，氣體注入需要加壓，但直接投放固體卻可利用其半封閉的特性大幅減少溢散量，進而減少加藥所需的能量，可有效減少碳排量。 本研究首先會在水中加入各種土壤中常見的鐵錳礦物，之後調整pH值至鹼性並加入不同濃度的次氯酸鈉，在適當的時間取樣以分光光度計法分析水中的鐵酸根或過錳酸根的濃度，以探討砂箱合成鐵酸根及過錳酸根的可行性及最佳的配比。結果顯示，由於高價鐵氧化物反應活性太高，與高價鐵氧化物有關的實驗都須以無機容器進行，以免容器消耗高價鐵物種。高濃度的六價鐵無法穩定存在於含有較低價固態鐵的環境中。七價錳的生成量與次氯酸鹽的添加量成正比。這主要是由於七價錳的化學活性較低，不會發生自身氧化還原作用所致。離地實驗中一氯酚及二氯酚均會在中性環境下被完全礦化，氧化2,4,6-三氯酚所需之六價鐵劑量較高，需以固態合成法現地合成高濃度的六價鐵注入，才能有效去除2,4,6-三氯酚。腐植酸等天然有機質是影響2,4,6-三氯酚去除效果的主要水質因子，可藉由增加添加量改善。現地實驗證實六價鐵藥劑之藥位置應配置於地下水污染層之上，氣態中和劑(乾冰)的注藥位置應配置於地下水污染層之下。相較於其他氧化劑，以乾冰為中和劑的六價鐵氧化法在資源成本及碳排量上均有明顯的優勢。
計畫英文摘要	Phenols and chlorophenol compounds are common contaminants in groundwater. The addition of oxidants or catalysts for the on-site treatment of these pollutants is a more economically viable option. Iron and manganese are common elements in soil, and their high oxidation states (iron sulfate and permanganate) can effectively remove chlorophenol compounds. However, excessive addition of these oxidants may lead to the formation of precipitates that can block soil pores and hinder transport. This study attempts to synthesize high-valent iron-manganese oxides in situ by injecting alkaline hypochlorite salts. This approach transforms iron and manganese elements from reactants into catalysts, eliminating the need for continuous injection of iron sulfate and permanganate to avoid the formation of insoluble iron-manganese precipitates that could clog soil pores and impede transport. Additionally, dry ice will be used as a neutralization buffer in later stages. As the soil groundwater system is a semi-closed environment, gas injection requires pressurization, but direct introduction of solids can take advantage of its semi-closed nature to significantly reduce dispersion and consequently decrease the energy required for dosing, effectively reducing carbon emissions. This study first adds various iron and manganese minerals commonly found in soil to water, then adjusts the pH to alkaline and adds different concentrations of sodium hypochlorite. Samples are taken at appropriate times, and the concentrations of ferrate or permanganate in the water are analyzed using spectrophotometry to explore the feasibility and optimal ratios for synthesizing ferrate and permanganate in a sandbox experiment. The results show that due to the high reactivity of higher-valent iron oxides, experiments related to higher-valent iron oxides must be conducted using inorganic containers to prevent the containers from consuming the high-valent iron species. High concentrations of hexavalent iron cannot stably exist in environments containing lowervalent solid iron. The amount of heptavalent manganese generated is proportional to the amount of hypochlorite added. This is mainly due to the lower chemical reactivity of heptavalent manganese, which prevents self-redox reactions. In off-site experiments, both monochlorophenol and dichlorophenol were completely mineralized in a neutral environment, while a higher dose of hexavalent iron was required to oxidize 2,4,6trichlorophenol. Solid-state synthesis must be used to produce high concentrations of hexavalent iron on-site for effective removal of 2,4,6-trichlorophenol. Natural organic matter, such as humic acid, is a major water quality factor affecting the removal of 2,4,6trichlorophenol, and the effect can be improved by increasing the dosage. On-site experiments confirmed that the injection location for the hexavalent iron reagent should be positioned above the contaminated groundwater layer, while the injection location for the gaseous neutralizer (dry ice) should be positioned below the contaminated groundwater layer. Compared to other oxidants, the hexavalent iron oxidation method using dry ice as a neutralizer has significant advantages in terms of resource cost and carbon emissions.