具再生系統之UV/NTFC 光催化觸媒反應器之研究

Abstract

奈米級零價鐵及二氧化鈦為近年來被廣泛研究與應用於處理環境污染物之材料。本研究室目前已發展出奈米級二氧化鈦/零價鐵複合材料(nanoscale TiO2/Fe0 composite, NTFC)，先前之研究顯示NTFC能有效的降解偶氮染料及硝酸鹽等污染物，其可改善二氧化鈦及零價鐵於應用上之限制。近年來亦有文獻指出，於二氧化鈦複合光觸媒處理污染物過程中，其處理環境之操作參數對於光觸媒處理污染物之效能亦具有極大之影響力。 本研究建立一具再生系統之UV/NTFC光催化觸媒反應器，以偶氮染料為目標污染物，進行效能測試及最佳化條件評估，效能測試以批次式試驗調整不同初始pH與溶液離子強度；最佳化評估中則以批次最適操作條件為依據進行實驗，實驗結束則以強力磁鐵進行觸媒顆粒的收集，進行再生試驗。反應同時進行溶液監測、分析污染物之降解以及顆粒粒徑分析。結果顯示，反應於酸性條件下能有效脫色及去除有機碳；而調整溶液離子強度環境中，結果指出在中高溶液離子強度條件下，均能有效脫色及去除總有機碳。連續流試驗中，使用過氧化氫進行奈米顆粒再生之效果較使用酸性再生佳。本研究證實此反應系統能使用NTFC顆粒有效於酸性條件下處理高色度廢水，並能利用過氧化氫有效進行奈米顆粒之回收與再生，可使顆粒再生後維持系統良好去除效率達24小時以上。

Nano-zero-valent iron (nFe0) and titanium dioxide (TiO2) are valid catalysts for the treatment of organic pollutants in wastewater. In previous studies, a novel TiO2/Fe0 composite (NTFC) material was prepared to overcome the restriction of utilizing nFe0 and TiO2. The NTFC can be successfully applied for degrading azo-dye in water. Also, many studies have indicated the significant impact of operating parameters on using the photocatalysts. The aim of this study was to develop a UV/NTFC pilot system to investigate the reductive ability of NTFC, the feasibility for azo-dye removal, as well as the optimization of operational conditions. In this work, the reactions departed into two parts, batch and continuous flow tests. The batch test adjusted the initial pH and ionic strength as the operating conditions. The continuous flow test proceeded under the optimal condition of batch test. Moreover, the catalysts were collected by the magnet after the reaction. The UV-Vis spectrometer and total organic compound (TOC) were used as parameters to evaluate the feasibility of azo-dye removal. Also, the colloidal particles of NTFC in UV/NTFC pilot system were determined by measuring their zeta potentials and particle size distributions. By monitoring pH, ORP and dissolved oxygen, it suggests the reaction follows a comprehensive mechanism of reduction and oxidation. The decolorization and TOC removal can be reduced by the batch test under acidic condition. Nevertheless, the decolorization and TOC removal rate could effectively decrease at different ionic strengths of solutions. In the continuous flow test, the result shows the catalysts can be regenerated by addition of the H2O2. And the reaction by regenerated NTFC can sustain for 24 hrs. In conclusion, the UV/NTFC pilot system can not only be successfully applied for the treatment of high color wastewater under acidic condition but also effectively regenerate the catalyst particles.