新穎高效能奈米TiO2/Fe0複合材料及UV/NTFC光催化反應系統之最佳化研究---製備與應用及光催化複合材料回收與再生

Abstract

零價鐵金屬與二氧化鈦已被廣泛應用於還原與氧化有機污染物，零價鐵應 用之主要缺點與限制為長期操作後表面包附氫氧化鐵氧化層，使得反應無法繼續 進行；二氧化鈦應用之主要限制為電子與電洞再回覆現象。因此，本研究擬以二 氧化鈦產生之標準電位差(-0.2 to 3.0 eV)延緩零價鐵表面氧化層之快速形成，並 利用氧化鐵為電子接受者，將二氧化鈦電子導引開，延緩電子與電洞再回覆現 象。依此理論提出新型奈米級二氧化鈦覆膜於奈米級零價鐵複合材料(nanoscaled TiO2/Fe0 composite；NTFC) 之開發，並結合冷陰極管紫外線(Cold Cathode Fluorescent Light; CCFL) 建立一UV/ NTFC反應系統以有效處理污染物。本研究 首先以新穎方式合成低溫、中性和具100% anatase 晶相之二氧化鈦，並將其覆膜 於零價鐵合成NTFC。所製備之NTFC將以FE-SEM, XRD, XPS, SQUID分析其特 性，並以2,4-dichlorophenol 環境荷爾蒙之去除作為光催化效能測試。研究內容 包含：（1）奈米級零價鐵與奈米級二氧化鈦合成方法之研究，（2）複合材料合 成之研究，（3）奈米級零價鐵與奈米級二氧化鈦添加比例對本複合材料還原與 氧化有機污染物效應之探討，（4）本複合材料處理污染物之機制與電子能階傳 遞相關性之探討，(5)建立高效率及高選擇性(氧化/還原)複合觸媒材料之製備流 程，(6) 建立全自動NTFC 奈米顆粒回收再生與再利用裝置，(7) pilot scale UV/NTFC反應系統之建立及程序最佳化之研究，期將此技術應用於產業界。

Zerovalent iron (ZVI) and titanium dioxide (TiO2) have been widely used in degradations of organic pollutants. The major obstacle of Fe0 application is the decreasing efficiency with time due to the formation of a surface oxide layer, while the electron-hole recombination in photocatalyst TiO2 hinders the reactivity of TiO2. The reduction potential of photocatalyst TiO2 is sufficient to transform ferric ion to ferrous ion. In this study, an innovative method is proposed to synthesize a novel TiO2/Fe0 composite (NTFC) to extend the life span of ZVI by retarding the formation of surface oxide layer on ZVI. The novel composite will be synthesized with a special chemical method from TiO2 and Fe0 nanoparticles, which will be prepared in the lab by a neutral sol-gel process and wet precipitation, respectively. The surface characteristics of the NTFC will be examined by using FE-SEM, XRD, XPS and chemical analysis. The photocatalytic performance of NTFC will be evaluated by the degradation of 2,4-dichlorophenol. The scope of the study include: (1) synthesis of ZVI and TiO2, (2) preparation and characterization of NTFC, (3) effect of ZVI and TiO2 ratio on catalytic efficiency of NTFC, (4) recovery, regeneration and reuse of spent NTFC, (5) optimization of a pilot UV/NTFC reactor with automated NTFC reuse system. The ultimate goal is to develop an applicable UV/NTFC reactor system of high selectivity and efficiency to remove persistent organic pollutants (POPs).