- 學位論文
應用普魯士藍有機金屬架構於鉈污染水體的復育與生物有效性監測
Applying prussian blue metal-organic frameworks on removing toxic Tl(I) in water and monitoring of bioavalability
摘要
鉈[Thallium, Tl(I)]為新興污染物且對生物體具有高毒性，目前針對去除水中鉈污染的方法仍有限。本研究利用胡等人於2012年所提出的合成方法合成普魯士藍有機金屬架構(PB-MOFs)，並評估其去除Tl(I)的能力。此法合成之PB-MOFs為邊長約190 nm的正立方體，其表面積約132 m2/g，且孔洞大小主要分布於10.77 Å。PB-MOFs對吸附Tl(I)具有高pH值依賴性，於pH = 2到10之吸附量隨pH值上升，並於pH = 8-9具有最大吸附容量約380 mg/g；在實驗結果中發現PB-MOFs於pH = 11時崩解導致吸附效果不佳。其吸附行為符合偽二級吸附動力曲線與Temkin等溫吸附曲線。水中干擾離子如Na+、K+、Mg2+、Cu+僅些微降低PB-MOFs的吸附容量，且PB-MOFs對環境濃度Tl(I)(50 μg/L)仍具顯著的吸附效果，我們推估PB-MOFs具有內外兩種吸附Tl(I)機制：(1)表面吸附：PB-MOFs於pH > 2時表面帶負電荷以吸附帶正電Tl(I)吸附速率高；(2)內層吸附：利用PB-MOFs的直徑約6.22 Å的內孔洞束縛住與內孔洞直徑相似的Tl(I)(水合直徑6.6 Å)，此吸附行為有專一性但所需時間較長，Tl(I)內外層吸附容量約略相等。PB-MOFs對青鱂魚（Oryzias latipes）幼魚不具急毒性且可有效移除Tl(I)之生物毒性；本研究進一步利用PB-MOFs對Tl(I)的吸附選擇性，將其吸附量與青鱂魚成魚中不同器官之Tl(I)累積量進行比較，以評估水中Tl(I)污染的生物有效性與毒性風險。
並列摘要
Thallium (Tl) is known as a technology-critical elements (TCE) with higher toxicity due to its non-biodegradable nature. The current methods for removing Tl pollution in water are still limited. This study used (proposed by Ming et. al (2012)) synthesized prussian blue metal-organic frameworks (PB-MOFs) and assessed the ability of PB-MOFs to remove Tl(I) in water. The PB-MOFs have a cube-haped streucture with a side length of 190 nm, and the surface area is about 132 m2/g. Our results showed that PB-MOFs have a high pH-dependency for Tl(I) sorption. The sorption capacity increased with pH value from pH 2 to10, with a maximum sorption capacity of approximately 380 mg/g at pH = 8-9. The sorption behavior followed the pseudo second order kinetic model and Temkin isotherm curve model. Environmental interference ions in natural water, such as Na+, K+, Mg2+, Cu+ only slightly reduced the sorption capacity of PB-MOFs. PB-MOFs still had significant sorption efficiency for Tl(I) at environmental concentration (50 μg/L). We proposed that PB-MOFs had both surface and inner layer sorption mechanisms. For surface sorption, PB-MOFs were negatively charged on the surface at pH > 2 to adsorb positively-charged Tl(I) at a fast rate. In the inner layer, the pores diameter of PB-MOFs are about 6.22 Å, which could trap Tl(I) with similar size (about .6.6 Å in hydrated diameter). While the inner layer sorption was more specific it required a much longer time compared to the surface sorption, thus leading to approximately equal sorption capacity on the inner and outer layers of PB-MOFs. This study further utilized larva medaka fish (Oryzias latipes) as a model organism and discovered that PB-MOFs did not cause acute toxicity while effectively reducing the toxicity of Tl(I) in fish. This study further evaluated Tl(I) adsorption selectivity of PB-MOFs and compared its sorption capacity to the cumulative amount of Tl(I) different organs of in medaka to understand the bioavailability and toxicity risk of Tl(I) pollution in environmental water.