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  • 學位論文

以摻釕和錳之活性碳去除全氟丁烷磺酸之研究

Removal of Perfluorobutanesulfonic Acid by Ru/Mn-loaded Activated Carbon

指導教授 : 駱尚廉

摘要


全氟化合物 (Perfluorinated chemicals, PFCs) 是一人工合成物,為良好之界面活性劑,被廣泛應用於工業與民生用品中,隨著長碳鏈PFCs之危害研究越來越多,現今許多產業逐步將短碳鏈PFCs作為長碳鏈之替代品,如全氟丁烷磺酸 (Perfluorobutanesulfonic acid, PFBS),因其具較小之毒性與生物累積性。然而,近年來在環境與生物體中陸續測得短碳鏈PFCs之存在,歐盟於2020年將PFBS加入高度關切物質清單中,美國環保署也於2021年修訂PFBS對人體健康之安全暴露劑量,因此發展有效去除短碳鏈PFCs之方法為重要之議題。 本研究利用改質活性碳 (OAC) 去除水中之PFBS,分析改質前後活性碳之比表面積、界達電位、表面結構和組成成分與鍵結,並探討pH值、OAC量、PFBS濃度和系統溫度對去除效果之影響。研究結果顯示,初始PFBS濃度為200 ppm且pH值為3.2之水樣,控制系統溫度為25 ℃時,加入10 g/500 mL之OAC反應30分鐘,有最佳PFBS去除效果,去除率為99.412 %,吸附量為9.901 mg/g,此吸附過程符合擬一階吸附動力模式與Freundlich等溫吸附模式。上述結果說明改質過程改變了活性碳的物化性質,進一步增加了OAC的吸附能力。 此外,將吸附過後之OAC重複利用,每次吸附後都會有部分的OAC吸附位置被填滿,造成去除速度和去除率逐次降低,去除率由第1次99.412 %降至第10次66.797 %,吸附量亦由第1次9.901 mg/g減少至第10次6.689 mg/g。 最後,將OAC用以吸附其他常見之PFCs,並比較PFBS和全氟辛酸 (Perfluorooctanoic acid, PFOA)、全氟辛烷磺酸 (Perfluorooctanesulfonic acid, PFOS) 之競爭吸附關係,實驗發現PFOS最易被吸附,PFBS最不易被吸附。而將OAC應用於實廠廢水,實驗結果顯示,實廠廢水中的有機物可能會和PFBS競爭吸附或阻擋吸附位置,使得PFBS之去除效果降低。

並列摘要


Perfluorinated chemicals (PFCs), a type of synthetic organic compounds, are widely used in industrial and household surfactants. Because of concern of their environmental and health hazards, many industries are gradually shifting the uses of long-chain PFCs to short-chain PFCs. The short-chain PFCs, such as perfluorobutanesulfonic acid (PFBS), have lower toxicity and bioaccumulation. However, short-chain PFCs have recently been detected in the environment and organisms. The European Union listed PFBS as a substance of very high concern in 2020. The US Environmental Protection Agency also updated the safe dose assessment for PFBS in drinking water sources in 2021. Therefore, development of effective methods for removal of short-chain PFCs is of importance. In this study, modified activated carbon, called OAC, was used to remove PFBS in wastewater. The Modification of activated carbon’s physical and chemical properties include its surface area, Zeta potential, surface structure, components and bonding on activated carbon. Additionally, the influences of pH, OAC doses, PFBS concentration and system temperature on the PFBS removal were also investigated. The experimental results indicated that the best removal of PFBS occurred when the initial PFBS concentration = 200 ppm, pH = 3.2, the system temperature = 25 ℃, and OAC dose = 10 g/500 mL. After 30 minutes, the removal reached 99.4 %, and the adsorption capacity was 9.90 mg/g. The adsorption process could be well fitted by the Pseudo-first order kinetic model and the Freundlich isotherm. The modification process changed the properties of activated carbon, which increased the adsorption capacity of OAC. Experiments were also conducted to evaluate the reusability of OAC. The removal was reduced from 99.4 % for the first run to 66.8 % for the tenth run, and the adsorption capacity also reduced from 9.90 mg/g to 6.69 mg/g, correspondingly. A competitive adsorption study among PFBS, perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS) was also conducted; it was found that the adsorption on OAC is PFOS > PFOA > PFBS. Finally, the experimental results of using actual wastewater suggested that the organic substances present in wastewater might decrease PFBS removal.

參考文獻


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