利用磁性光觸媒去除水中甲基第三丁基醚之研究

Removing MTBE in water by using magnetic photocatalysts

沈志修(Chih-Hsiu Shen)

指導教授 ： 駱尚廉

國立臺灣大學/工學院/環境工程學研究所/博士(2011年)

https://doi.org/10.6342/NTU.2011.02070

摘要

本研究以溶膠凝膠法(Sol-Gel)改良傳統TiO2光觸媒，藉由添加Fe3O4或NH4VO3促進Rutile晶型結構生成，形成TiO2-Fe3O4及V-TiO2複合式光觸媒，以增加光觸媒對可見光之利用性。以SEM分析TiO2-Fe3O4及V-TiO2 光觸媒，經過研磨過篩後，其表面顆粒達20 nm 之奈米級粒徑。經XRD分析反應前之TiO2-Fe3O4及V-TiO2 光觸媒，皆存在著Anatase及Rutile晶體結構，經降解MTBE後，發現TiO2-Fe3O4主要高峰2θ值有25.4（Anatase）、36.2（Rutile）、48.2（Anatase），晶體結構仍保有Anatase及Rutile。相反地，反應後之V-TiO2，其2θ值27.5峰值消失，代表Rutile結構產生破壞。
以TiO2-Fe3O4複合式光觸媒進行結晶紫染料退色反應測試中，三次重複回收之磁性光觸媒，其染料退色試驗結果並無明顯差異，且無論在可見光或UV光源下複合式TiO2-Fe3O4光觸媒都比TiO2光觸媒有更佳的光催化效應，證明複合式TiO2-Fe3O4光觸媒的耐久性。 在最佳劑量試驗中，以5 g的TiO2-Fe3O4複合式光觸媒催化劑，對水溶液中MTBE可達到較高的移除效率（91 %），其次分別為10 g、2 g及1 g；V-TiO2則是以0.10VT-I合成比例具有82 ％MTBE移除率。
本實驗設計分別以循環式及密閉式系統降解MTBE，於循環式光反應系統中，TiO2-Fe3O4光觸媒於pH10具有較佳MTBE降解效果，而V-TiO2光觸媒則是pH7具有較佳降解效果。於密閉式反應系統中，pH7及pH10對V-TiO2、TiO2-Fe3O4而言，降解MTBE效果相近。考量核心材料Fe3O4及NH4VO3所造成成本之差異，在相近移除率下，應以成本低者優先考量，再者，Fe3O4具有磁性，具有利用磁場回收再使用之可能，故TiO2-Fe3O4光觸媒較具實場應用優勢。

關鍵字

溶膠凝膠法 ； 甲基第三丁基醚 ； 可見光 ； 高溫金紅石 ； TiO2-Fe3O4 ； V-TiO2

並列摘要

The objective of this research was using Sol-Gel method to improve the conventional TiO2 catalysts. In order to increase the utility of visible light, ferroferric oxide and ammonium vanadate were composite of TiO2-Fe3O4 and V-TiO2 to provide the Rutile type structure, respectively.
Both TiO2-Fe3O4 and V-TiO2 catalysts treated by grinding and sieving, their average particle sizes were near 20 nm by SEM analysis. As shown in XRD results, Anatase type and Rutile type structures appeared in both TiO2-Fe3O4 and V-TiO2 catalysts before MTBE decomposition. Otherwise, the major 2θ values of TiO2-Fe3O4 appeared in 25.4（Anatase）, 36.2（Rutile）and 48.2（Anatase）, so it means Anatase type and Rutile type structures still existed after MTBE decomposition. Oppositely, one 2θ peak in 27.5 of V-TiO2 disappeared after MTBE decomposition, owing to Rutile type structures broken.
Observed the continuous discoloration experiments by composite TiO2-Fe3O4, the results of discoloration seemed to be not different in spite of three time reuses. Whether photocatalysts irradiated by Visible light or UV light, the performance of composite TiO2-Fe3O4 was rather than pure TiO2, and this also meant the durability of composite catalysts.
In the optimum doses experiment, it showed adding 5 g TiO2-Fe3O4 could achieve 91 % MTBE removals, and followed by the 10 g, 2 g and 1 g. Besides, V-TiO2 catalysts has 82 % MTBE removals, which atomic ratio of vanadium to TiO2 was 0.1 (0.10VT-I).
Continuous and close photoreactor systems were designed to degrade MTBE in this research. Under continuous system, pH10 was helpful for TiO2-Fe3O4 catalysts to gain better MTBE removals, but V-TiO2 photocatalytic degradation has better results under neutral pH 7. However, both V-TiO2 and TiO2-Fe3O4 have similar photocatalytic degradation results under close system whatever the pH value was pH 7 or pH 10.
Considered the material cost difference between Fe3O4 and NH4VO3, it should be adopted lower price first if their removals were very similar. Moreover, the Fe3O4 material has magnetism, so TiO2-Fe3O4 could be reused by external magnetic field while TiO2-Fe3O4 has more potential value in real.

並列關鍵字

Sol-Gel method ； methyl tert-butyl ether ； visible light ； Rutile type ； TiO2-Fe3O4 ； V-TiO2

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