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標題: | 腐植酸對三價鎵和銦之吸附作用 Adsorption of Trivalent Gallium and Indium by Humic Acid |
作者: | Wan-Ting Liew 廖婉婷 |
指導教授: | 王尚禮(Shan-Li Wang) |
關鍵字: | 鎵,銦,腐植酸,吸附,X 光吸收光譜, Gallium,Indium,humic acid,Adsorption,X-ray Absorption Spectroscopy, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 隨著半導體、光電和能源等高科技新興產業的發展,鎵和銦及其他具有特別理化性質的元素被使用於相關製程中,並釋放至環境當中。臺灣已發現許多科技產業園區周遭地下水的鎵和銦濃度較自然背景為高,可能造成土壤污染並藉由作物進入食物鏈對人體和生態產生危害,故必須瞭解這些污染物進入土壤後的物種型態與宿命。土壤中吸附反應決定金屬離子的移動性和生物有效性,腐植酸是土壤系統中有機物質中腐植物質組成分之一,因具有各類官能基而具有與重金屬錯合的能力,在土壤環境中金屬的傳輸扮演重要的角色。為了釐清土壤中有機物質對鎵與銦的影響,本研究將以腐植酸作為吸附劑進行鎵和銦離子的吸附反應,以期探討腐植酸與鎵和銦之間的反應機制。在低 pH 值 (pH 3.0 – 6.0) 環境溶液中,腐植酸對鎵和銦皆有高吸附量,形成不具移動性且穩定的錯合物型態。隨著 pH 值的遞增,在高 pH 值環境中 (pH 8.0 以上) ,鎵是以具移動性的物種型態存在,且其含量隨著溶液中可溶性碳濃度含量的增加而上升;銦則是以不具移動性的錯合物型態,且含量隨著 pH 值的遞增而增加。其中鎵和銦分別在鹼性及中性 pH 值環境中具有最大移動性。反應時間與溶液離子強度的增加同時促進了:溶液中具可移動性的鎵,具可移動性的銦 (pH 3.0 – 6.0) 及腐植酸-銦穩定型態錯合物 (pH 7.0 – 11.0) 含量的增加。從 XANES 及 EXAFS 光譜分析數據得知,吸附實驗中鎵和銦皆無沉澱物生成,表示在有腐植酸的系統中,鎵和銦產生沉澱物之機率降到最低。 因此鎵和銦被腐植酸所吸附時,其移動性和有效性可能因此而增加,導致環境風險隨之增加。 The development of semiconductors and optoelectronics industries has resulted in the release of gallium (Ga) and indium (In) into the environment, which could pose a threat to public health. To lower the environmental risk of these emerging pollutants, it is crucial to understand their fates in the environment. In soil environments, the adsorption and desorption reactions of pollutants by soil constituents determines their mobility and bioavailability. Humic acid is one of soil colloids, which play an important role in determining metal mobility and bioavailability in soil. This study investigated the adsorption mechanism of humic acid on Ga and In ions. The adsorption experiments were carry out under several different conditions including solution pH and ionic strength. The experimental results revealed that humic acid has strong affinity for Ga and In as indicated by the high adsorption capacity of humic acid for Ga and In. Ga and In were bound to humic acid through forming a non-mobile and stable complex in low pH range (pH 3.0-6.0) solution. A mobile species of Ga-humic acid complexes formed at pH 8.0 and above. Comparatively, In was reacted with humic acid to form an immobile complex at different pHs. Meanwhile, Ga and In have the highest mobility in alkaline and neutral pH conditions, respectively. The results of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) show that the coordination environment of Ga-humic acid complexes changed with increasing solution pH, while that of In-humic acid complexes remained the same. No precipitation occurred in either Ga or In system. Thus, the adsorption of Ga and In on humic acid may result in the increase in the mobility and availability of Ga and In, which may consequently increase their environmental risks. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/66803 |
DOI: | 10.6342/NTU202000024 |
全文授權: | 有償授權 |
顯示於系所單位: | 農業化學系 |
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