製備環境復育用之重質非水相奈米零價鐵懸浮液

Preparation of Dense Non-aqueous Phase Nano Zero-valent Iron Suspension for Environmental Restoration

劉佩格(Pei-Ge Liu)

指導教授 ： 吳先琪

國立臺灣大學/工學院/環境工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.03421

摘要

重質非水相液體(DNAPL)污染之土壤地下水之整治為現今最棘手問題。主要瓶頸在於DNAPL物化性質特殊與傳輸性質複雜，難以掌握污染源位置，去除不易。目前整治技術多以處理溶解於水相中溶解態污染物，對於殘餘相及 DNAPL蓄積池之處理有限。

本研究以合成十八烷基磷酸二氫酯(ODP)作為表面修飾劑對零價鐵進行表面改質，使其成為疏水性之奈米顆粒，並探討其性質及其對DNAPL之反應效能。XRD繞射圖顯示表面修飾後疏水性奈米鐵，在2θ為44.9°出現波峰，發現表面具有零價鐵金屬性質。由FTIR圖譜顯示ODP可直接鍵結上無分散劑之疏水零價鐵粉顆粒表面；添加分散劑之奈米零價鐵粉，表面已先被PAA之羧酸根鍵結，ODP與PAA間形成氫鍵或脫水形成酸酐之作用力使其仍具有極佳疏水性。測試疏水奈米零價鐵粉潤溼性，表面接觸角超過100度，尤其ODP與添加分散劑PAA後之奈米零價鐵重量百分比為5 % wt時，有最大接觸角133度。疏水奈米零價鐵可分散於正辛醇形成重質非水相奈米鐵懸浮液(dense non-aqueous phase nano iron suspension, DNAPNIS)，濃度可達300 g-Fe/L，黏滯度為280 cp。

最後，探討DNAPNIS對TCE反應性測試。在含有TCE總質量為8.7 mg，TCE在油相初始濃度為4384 ppm之血清瓶中，添加2 ml濃度為300 g-Fe/L以正辛醇做為溶劑之DNAPNIS。經90分鐘之反應，TCE濃度減少約23 %，至267小時，TCE去除率為54 %。

本研究中製造之DNAPNIS在飽和含水砂柱中之貫穿試驗中，因油層極薄，無法構成足夠之液壓差以突破表面張力及黏滯阻力，僅略侵入飽和砂柱，而無法貫穿。

關鍵字

零價鐵 ； 表面改質 ； 疏水性奈米顆粒 ； 重質非水相奈米零價鐵懸浮液 ； 三氯乙烯

並列摘要

The remediation for dense non-aqueous phase liquids (DNAPLs) in soils and aquifers is the most difficult problem at present. Because of the complex nature of the transport of DNAPL and its special physical and chemical properties, it is particularly difficult to detect and characterize these kind of pollution sources. Most of the technologies are applicable only to contaminants in the dissolved phase. Treatment technologies currently being applied to the remediation of the residual zones and DNAPL pools are limited.

In this study, octadecyl dihydrogen phosphate (ODP) was synthesized and applied as surface modifier to produce hydrophobic zero-valent iron (HZVI). The properties of the HZVI and its capability of degradation of DNAPL were examined. The HZVI retained the surface properties of zero-valent iron which was verified by X-ray powder diffraction (XRD). ODP can bond to the particle surfaces or the particle surfaces covered by carboxylic acid group of polyacrylic acid (PAA). Hydrogen bonds as well as anhydride formed between ODP and PAA make the particles well covered by ODP and kept hydrophobic. The contact angle of HZVI in the test of wettability is over 100 degrees. The maximum contact angle was 133 degrees when the dosage of modifier was 5 % wt. The hydrophobic nano zero-valent iron can well be dispersed and stabilized in non-aqueous solvents. The stable dense non-aqueous zero-valent iron suspension contain 300 g-Fe/L in 1-octanol with viscosity at 280 cp.

The reactivity of the dense non-aqueous phase nano zero-valent iron suspension with 8.7 mg of TCE in amber serum bottle was investigated. Two milliliters of dense non-aqueous phase nano zero-valent iron suspension with concentration of 300 g-Fe L-1 in 1-octanol as a solvent was injected into the bottle. TCE concentrations decreased 23 % in 90 minutes, and the total removal rate of TCE was 54 % in 267 hours.

Only slight penetration of a blob of dense non-aqueous zero-valent iron suspension into saturated sand column occurred due to very small difference between hydraulic heads of water column and the tested liquid, high surface tension and high viscosity of the tested liquid.

並列關鍵字

zero-valent iron ； surface modifier ； hydrophobic nano particles ； dense non-aqueous zero valentiron suspension ； trchloroethylene

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