EPA-102-1603-02-01

102

1,479 千元

2013/02/27

2013/12/31

施養信

環檢所

黃豊文

國立台灣大學農業化學系

環境監測及檢測

無機性奈米微粒，動態光散射技術，模擬廢水基質，離心，流力層析，聚集，沉降，穩定性

Inorganic nanoparticles, dynamic light scattering (DLS), wastewater surrogate, centrifugation, hydrodynamic chromatography (HDC), aggregation, sedimentation, stability

蘇昱帆

李孟潔

02-33669442#

preludeincmajor@gmail.com

奈米微粒在水中之分析技術是目前國際上奈米科技的重要議題與關鍵技術，所以本研究針對使用無機性奈米微粒之工廠廢水採樣，評估以離心、過濾或滲透膜等方式去除溶液中顆粒等奈米量測時之干擾物質，藉以保留實際廢水中的離子強度或pH等物化特性，作為該工廠之模擬廢水基質，藉由此模擬廢水來研究開發奈米量測方法。廢水中去除顆粒實驗以滲透膜過濾效果最好，其次為離心及濾膜過濾方式，但滲透膜過濾及離心花費時間較長，考慮到時間成本以及實驗便利性，模擬廢水基質以過濾0.1 µm濾膜方式製備。 　　奈米Ag懸浮液測得DLS平均粒徑79.86 nm (PdI=0.206)，等電點(pHzpc)約pH 1，介達電位(zeta-potential)隨pH上升而下降(趨向帶負電)。穩定性實驗中，奈米Ag於純水或廢水基質中，在25℃及4℃環境下，粒徑及PdI皆維持穩定。奈米Ag於純水或廢水基質中，在25℃時的Ag離子釋出量皆較4℃時高，建議以低溫避光之保存條件較為適當。干擾性實驗中，微米SiO2及奈米Ag濃度比達100：1時，微米SiO2會干擾奈米Ag的DLS量測結果；奈米Ag於接近等電點時(約pH 1)，微粒迅速聚集；但廢水中的鹽類濃度(163 mM)與總有機碳濃度(40 ppm)對奈米Ag的DLS粒徑量測影響不明顯。水體環境參數影響部分，酸鹼度對於奈米Ag而言，顆粒粒徑在接近等電點(~pH 1)時有明顯的顆粒粒徑變大與沉澱現象。鹽類影響部分，NaCl對於奈米Ag的臨界聚集濃度約為500 meq/L；CaCl2對於奈米Ag的臨界聚集濃度約為200 meq/L，而腐植酸對於奈米Ag粒徑則無顯著的影響。 　　不同粒徑顆粒分離前處理實驗中，以4060 G，2分鐘離心，可有效將微米級SiO2或奈米級TiO2與奈米Ag微粒分離，並分別得到64%與40%回收率。針對離心所不能分離的較小尺度的顆粒，則可使用流力層析(hydrodynamic chromatography, HDC)分離。以HDC方式可分離出在純水、模擬廢水基質及廢水中不同標準粒徑之奈米銀，粒徑越大，滯留時間越短，粒徑越小，滯留時間越長。由滯留時間與粒徑關係圖，可量測出顆粒粒徑大小，配合ICPMS分析可測得其濃度。

無機性奈米微粒，動態光散射技術，模擬廢水基質，離心，流力層析，聚集，沉降，穩定性

EPA-102-1603-02-01.pdf

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2014/2/1 上午 12:00:00

This study aims to develop an analytical method for detecting inorganic engineering nanoparticles in the effluent of nanoparticle factories. The centrifugation, filtration, and dialysis technology have been adopted to take out all particles in the industrial wastewater from nanoparticle factories as a wastewater surrogate which still reserves the water chemistry properties including pH, ions, inorganic and organic matters, to establish nanomaterial detection methods. Dialysis technology showed the best performance to remove particles in the industrial wastewater. However, centrifugation and dialysis technology were time-consuming and costly. Filtration with 0.1 µm filter was applied to prepare the wastewater surrogate. The particle size of nanoscale-Ag particles (nano-Ag) determined by DLS was 79.86 nm (PdI=0.206). The pHzpc of Ag nanoparticles was near pH 1. The zeta potential decreased with increasing pH. The particle size and polydispersant index of Ag nanoparticles keep stable in DI-water and wastewater surrogate at 4oC and 25oC. The concentration of dissolved Ag ions from Ag nanoparticles at 25oC is higher than that at 4oC. The preservation for nanoparticle samples was suggested to keep at 4oC without light. Microscale SiO2 (micro-SiO2) particles interfered the DLS measurement of Ag nanoparticles when SiO2/Ag concentration ratio was higher than 100. The Ag nanoparticles aggregated at pHzpc (pH 1). The effect of salt and humic acid in wastewater surrogate on DLS measurement of Ag nanoparticles was insignificant. The influences of three main aqueous parameters, pH, electrolyte, and humic acid, on nanomaterials in water were discussed. The obvious aggregation and sedimentation behaviors were found when the aqueous pH value was close to the pHzpc of Ag nanopartilces (~pH 1). The critical aggragation concentration (CAC) value of Ag nanoparticles was approximately 500 and 200 meq/L for NaCl and CaCl2, respectively. Humic acid did not cause the aggregation and sedimentation of Ag nanoparticles. To remove microscale particles, the centrifugation with 4060 G for 2 min was effective to separate nano-Ag particles from micro-SiO2/nano-Ag and nano-TiO2/nano-Ag, and the recoveries were 64% and 40%, respectively. The other technology was applied to separate different sizes of nanoparticles is hydrodynamic chromatography (HDC). HDC can separate different sizes of Ag nanoparticles in water, wastewater surrogate, and wastewater. The larger size of nanoparticles has the shorter retention time. We can measure the particle size by the particlee-retention time from the calibration curve built by the well-known size of nanoparticles in the tested medium. With the cooperation of ICPMS, the concentration of the separated nanoparticles of the separated nanopatticles, by HDC can be measured.

Inorganic nanoparticles, dynamic light scattering (DLS), wastewater surrogate, centrifugation, hydrodynamic chromatography (HDC), aggregation, sedimentation, stability