摘要

奈米銀微粒(AgNPs)因為擁有良好的抗菌性而在生活中被廣泛地使用，在32個國家的統計裡，奈米銀是日常用品中使用頻率最高的奈米材料(24%)，但是其產生的銀離子會與自然界中的天然有機物(NOM)結合並且於陽光下還原成AgNPs散布在環境中，因此，本研究主要探討在土壤、河川、汙水和湖泊中的溶解性有機物(DOM)對於銀離子的光還原反應所造成的影響。
本研究中我們使用了包括土壤、河川、汙水廠和湖泊等不同DOM，並且利用分光光譜儀所測出的七種光學參數來分析水體與AgNPs的產生，所使用的參數包括S275-295、 S350-400、 S290-600、 SR、SUVA 254、 SUVA 280和E2/E3。在結果中顯示，DOM的來源顯著地影響AgNPs在自然水體中的光化學生成，其中DOM的分子量大小和腐殖化程度扮演著重要的角色，在S275-295 和 E2/E3與AgNPs產率的線性回歸中有明顯的相關性，代表著DOM的分子量越大、腐殖化程度越高都會銀離子的光還原反應。
關鍵字:奈米銀、溶解有機物、光還原反應、分光光譜儀。

Abstract

Silver nanoparticles (AgNPs) are a commonly used nanoparticle and have useful characteristics such as excellent antibacterial property. A recent survey indicates that AgNPs are one of the most frequently used (24%) nanomaterials in the consumer products available on the markets across 32 countries. AgNPs once released into the environment could be oxidized to form silver ions which could be bound to dissolved organic matter (DOM). It has been shown that silver ions can be photoreduced to form AgNPs by natural organic matter (NOM) under sunlight conditions. Given that there is a range of DOMs that could be found in the environment, the aim of this thesis is to evaluate the effect of DOM samples isolated from soils, rivers, wastewater effluents, and lakes on the photoreduction of silver ion to form AgNPs.
In this study, we used ten different DOM samples isolated from soils, rivers, wastewater effluents, and lakes. We evaluated the characteristics of DOMs including spectral slopes (S275-295, S350-400, and S290-600), slope ratio, SUVA 254, SUVA 280 and E2/E3 in relation to their photoreduction of silver ions to form AgNPs. The result indicated that the sources of DOM significantly affected the formation of AgNPs in aqueous solutions. It was shown that molecular weight, DOM size, and the degree of humification played a role in the photochemical formation of AgNPs. The linear regression result of slope ratio, S275-295 and E2/E3 indicated that DOM samples with higher molecular weights and degree of humification correlated with their greater capabilities to effect photoreduction of silver ions.
Keywords : dissolved organic matter sources, formation of AgNPs, silver nanoparticles, UV-visible absorbance.

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