穩定奈米零價鐵顆粒之製備及在多孔介質中之傳輸

Abstract

以零價鐵顆粒去除地下水水中污染物質，如多氯乙烷或氯乙烯，已受到廣泛研究與運用。本研究嘗試將不同界面活性劑加入溶液中製備穩定的奈米鐵懸浮液。如此，處理地下水污染物時，可以鑿井注入方式將奈米鐵懸浮液注入地下水層中，增加傳輸效果，任其擴散至定點，以處理地下水中之含氯碳氫化合物。 研究中使用連續流方式自行製備奈米零價鐵顆粒，並於管線中加入不同之界面活性劑後，探討鐵顆粒在懸浮液中的穩定效果。在界面活性劑的選擇方面，實驗發現市售清潔劑比文獻中常見之界面活性劑SDS (sodium dodecyl sulfate)可使奈米鐵顆粒達到更好的懸浮效果，且對環境之危害較小。實驗結果顯示製備奈米鐵顆粒之原料硫酸亞鐵及硼氫化鈉在濃度為0.009M及0.053M時，生成的奈米鐵顆粒粒徑較小且可達到較好的懸浮效果。實驗於連續流裝置中加入濃度6936 mg L-1市售清潔劑可大幅提升奈米鐵顆粒的懸浮效果且顆粒粒徑經過TEM 顯微鏡觀察約40-150 nm。 實驗最後進行奈米鐵顆粒之土柱貫穿試驗，暸解奈米鐵顆粒於50公分土柱中之傳輸效能。實驗得知約50 %之奈米鐵顆粒貫穿土壤管柱。

Zero valent iron (ZVI) has been widely used for reducing the pollutants such as poly-chlorinated ethane and ethylene in contaminated groundwater aquifers. However, the cost for delivering and retaining ZVI at certain location in environmental matrixes may be high. It was my attempt to develop a technique that could stablize the nano-scale iron particles by adding different surfactants. So that, we may deploy nano-scale iron particles into groundwater aquifers by way of injection. In this study, different surfactants were added to the suspension of nano iron particles that was prepared with a continuous manufacturing system. A commercialized, environmental-friendly dish-washing detergent was found to better keep nano-iron suspending than sodium dodecyl sulfate (SDS), which is a commonly used surfactant in literatures. Stable suspension of nano-scale iron particles with diameter of 300nm to 1μm were made by mixing two solutions with concentrations of 0.009M FeSO4 and 0.053M NaBH4, respectively. Adding commercial detergent at a concentration of 6936 mg L-1 in the continuously manufacturing system produced stable iron particles in the suspension with size ranging from 40 to 150 nm observed by TEM. Nano-scale iron suspension was passed through a 50-cm-long soil column to minic the transport in the field soil. About 50 % of nano-scale iron passed through the soil column.