鑭摻雜二氧化鈦光催化劑對環境污染物降解應用之研究

The Application of Lanthanum Doped Titanium Dioxide Photocatalyst on Environmental Pollutant Degradation

張根穆(Chang-Ken Mu)

指導教授 ： 王雅玢

中原大學/工學院/土木工程研究所/博士(2019年)

https://doi.org/10.6840/cycu201900018

摘要

本研究藉由製備鑭金屬摻雜二氧化鈦光催化劑，再塗布於不同載體，探討其運用於不同環境污染物降解之效益及可行性，並藉由光催化動力分析，瞭解固-氣相及固-液相環境下光催化反應動力之差異，做為未來持續研究之參考。
首先利用酸浸法將廢螢光粉中的稀土金屬酸浸出來，並將其鑭金屬摻雜二氧化鈦，再利用PVDF薄膜經由低溫電漿改質，並以製備之鑭摻雜二氧化鈦塗佈於薄膜上，分別探討其光催化降解染劑之光催化活性及效益。光催化反應實驗結果顯示，以1wt%鑭添加劑量效果最好；於測試不同光源的實驗中，顯示藍光效果最好，並測試其光催化劑重複性，結果顯示，可重複高達11次。另將1wt%La-TiO2塗佈於薄膜上後，其光催化降解染料的效率略為下降，但可大幅提升其反應動力。La-TiO2/PVDF薄膜將大幅提升光催化劑之親水性及滲透性。
利用鑭金屬摻雜二氧化鈦及塗佈於玻璃纖維布，分別用於模擬光催化降解地下水污染整治SVE法尾氣中甲苯（Toluene）。其研究結果顯示在經由加濕處理於濕度60%的環境濕度，1 wt% La-TiO2塗部於玻璃皿上降解甲苯效果可達22.8%，而塗佈玻璃纖維布載體光催化降解實驗中，三片光催化玻璃纖維布可達94.84%，在可見光條件下，光催化La-TiO2/玻璃纖維布可達54.32%，綜合上述濕度及載體條件，採用環境濕度60%及1 wt% La-TiO2塗佈於玻璃纖維布為其研究開發光催化之模組設計。另若以載體附載密度評估光催化模組之成本效益，仍以使用1片載體布為較佳選擇。
另本研究以循環經濟為出發點，萃取廢棄螢光粉中鑭元素改質二氧化鈦，並利用含浸法將塗料均勻塗布於陶瓷過濾片上，並探討光催化材料於室內低濃度之污染氣體的處理性能。實驗結果顯示本研究製備之光催化空氣濾片，使用可見光降解丙酮以0.5wt%La/TiO2具最佳降解效果為36.9%，比商業二氧化鈦之23.5%更佳。且使用可見光降解一氧化氮以0.5wt%La/TiO2具最佳降解效果為77.2%與二氧化氮生成量8ppb，明顯優於商業二氧化鈦之NO降解效率且可抑制NO2生成率，同時抑制二氧化氮的生成。整體而於丙酮或一氧化氮的降解效果明顯較商業型二氧化鈦更佳，且塗布於陶瓷過濾片將能大幅提升光催化的降解效率。
最後彙整本研究以La改質TiO2在塗布於載體後於氣、液相光催化降解污染物之反應動力，由前述實驗結果及反應速率常數可知，La/TiO2-載體於可見光照射環境下，不論運用於氣相或液相相較商用二氧化鈦均可大幅提升光催化反應動力，其中以氣相降解NO反應動力最佳且反應時間最短。而於固液相及固氣相光催化實驗兩者所得之催化反應動力並無明顯優劣差異，顯示經由改質TiO2光催化劑及塗佈載體等程序製備之光催化劑，可同時適用於固液相及固氣相之光催化降解污染物用途，且整體反應動力表現較相關文獻研究結果類似或較佳。

關鍵字

光催化反應 ； 鑭摻雜二氧化鈦 ； 親水性 ； La-TiO2/PVDF薄膜 ； 載體

並列摘要

In this study, Lanthanum (La)-doped with TiO2 photocatalyst was synthesized by utilizing recycled La from the waste fluorescent powder. Subsequently, the feasibility and benefits of various pollutants degradation, coating of various carriers and photocatalytic kinetics under solid-gas phase and solid-liquid phase was investigated by photocatalytic dynamic analysis.
First, the rare earth metal in waste fluorescent powder was leached by acid agents and then La-doped TiO2 and coated on the PVDF film which was modified by low-temperature plasma. The photocatalytic activities and benefits of dye degradation were discussed. It was found that the best result is 1wt% La additive under the blue light (450-495 nm) irradiation and the result indicates that it could be repeated up to 11 times. Although the efficiency of photocatalytic dye degradation slightly decreased after coating the La/TiO2 on the film, however, the kinetic, hydrophilicity and permeability of reaction could be greatly improved.
The utilization of La-doped TiO2 and fiberglass cloth coating are used on simulating the photocatalytic degradation of toluene from the exhaust gas by SVE method applying on groundwater contamination site. The results interpret that 1 wt% La doping into TiO2 on glass is 22.8% of toluene degradation by humidity of 60%. The toluene degradation could reach up to 94.84% for three fiberglass cloth coated with La-TiO2 under UV light. The toluene degradation could still reach up to 54.32% under visible light irradiation. The recommended module design is under 60% of relative humidity and 1 wt% La-TiO2 coated on fiberglass cloth. The one piece of cloth is the best cost-effectiveness choice.
This study was also based on the circular economy. The lanthanum in waste fluorescent powder was extracted then doped with TiO2, and the La-TiO2 complex was coated on the ceramic filter by immersion method. The acetone degradation was 36.9% under 0.5wt% La/TiO2 coated on ceramic filter, while it is 23.5 % for the commercial TiO2. The best efficiency of NO degradation is 77.2% and NO2 generation was only 8ppb which is better than commercial TiO2. Accordingly, the degradation efficiency of acetone and NO for La-TiO2 coated ceramic filter is better than commercial TiO2.
The results of experiments and reaction rate constants indicated that the photocatalytic reaction of La/TiO2- assisted under visible light irradiation was greatly increased than commercial TiO2. The optimal degradation reaction for gas phase pollutants (NO, toluene, acetone) is NO with the shortest reaction time.

並列關鍵字

photocatalytic reaction ； La doped TiO2 ； hydrophilicity ； La-TiO2/PVDF membrane ； acetone, ； NO

參考文獻

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