微波水熱法合成N-TiO2：鑑定與光催化降解5-氟尿嘧啶之研究

Abstract

隨著各種污染物的增加以及生活習慣的改變，癌症成為現代社會聞風喪膽的文明病，使得抗癌藥物 ( anticancer drugs ) 的種類及用量逐年遞增，因此主要針對藥品和個人護理用品 ( pharmaceuticals and personal care products, PPCPs ) 中的抗癌藥物進行研究。由於此類藥物大多數不易被生物分解而造成持久性及生物累積性，並透過食物鍵或飲水系統進入生態圈，導致抗藥性的提高甚至蓄積在生物體內而引發內分泌失調、生育力下降等風險。本研究主要利用具有氧化能力強、處理效率高及操作程序簡單等優點之光催化反應，藉以降解 5-氟尿嘧啶 ( 5-fluorouracil ) 及環磷醯胺 ( cyclophosphamide )。 本實驗改變四種實驗參數以合成可見光光觸媒 N-TiO2，分別為 NH4OH 水溶液之浸泡濃度、微波水熱反應時間、微波水熱反應溫度，及於管狀高溫爐中通 NH3 鍛燒的時間，並利用 5-fluorouracil 之降解評估最佳化合成 N-TiO2 之製備條件，再利用最佳化之光觸媒，進行 cyclophosphamide 之光催化降解。實驗將著重於改質後之 N-TiO2 與改質前之 P25 TiO2 進行比較，使用 XRD、UV-Vis、表面積分析儀、 SEM 及 TPD 進行觸媒結構與表面分析，藉以探討與光催化活性之關聯性。 研究結果顯示，經由 N改質之TiO2 光觸媒，與 P25 TiO2 相比較，其表面鹼量下降，並能使吸收波長往可見光波長位移且光觸媒能隙 ( band gap ) 變小，但平均粒徑大小增加為 30 ~ 40 nm，顆粒有變大的趨勢，且有明顯的團聚現象。於藍光下對 5-fluorouracil 催化降解，得到最佳化觸媒 N6-TiO2 之製備參數為：管狀高溫爐中通 NH3 鍛燒 6小時、微波水熱反應 3小時、微波水熱反應溫度為 180℃ 及浸泡於 1 M之 NH4OH 水溶液中。而N6-TiO2 於藍光下降解cyclophosphamide，其去除效率並未較 P25 TiO2 佳，故最佳化之光觸媒對於降解 5-fluorouracil 有較佳的光催化活性，但對於降解其他的藥物並不是最適化。

Cytostatic drugs are a class of pharmaceuticals that are increasingly prescribed for cancer therapies, among which 5-fluorouracil and cyclophosphamide are the most commonly used cytostatic (antineoplastic) drugs in the world. These pharmaceuticals could interfere with the structures and functions of DNA and have been reported to cause cytotoxic, genotoxic, mutagenic, and carcinogenic effects on non-target organisms. This study applied photocatalytic oxidation to remove 5-fluorouracil and cyclophosphamide. Nitrogen doped TiO2 nanoparticles were synthesized through a microwave hydrothermal process using ammonia water as the doping species. The resulting materials were characterized by XRD, UV-Vis, BET, SEM, TPD and zeta potential analyzer. XRD patterns can be well indexed to the mixed phases of anatase and rutile, and the modification of the TiO2 particles by N did not cause any change in their peak positions and shapes compared with the neat TiO2 (P25). UV-Vis results indicated that the light absorbance edge of nitrogen doped TiO2 nanoparticle was red-shifted to visible light region. The process of nitrogen modification caused a reduction in the specific surface area and the presence of mesoporous structures. From SEM pictures, the N-doped TiO2 was 30-40 nm in size and obviously aggregated compared with the neat TiO2 (P25). With nitrogen modification, the basicity on the N-TiO2 surface decreased and the pHZPC values did not change apparently. The highest level of photocatalytic activity was N-TiO2 which was synthesized by 1 M NH4OH immersion, 3 hours microwave at 180℃ and 6 hours calcination in NH3 gas at 550℃ for degradation of 5-fluorouracil. Cyclophosphamide removal by optimized N-TiO2 was not better than that of P25. In conclusion, the optimized N-TiO2 has more efficient photocatalytic activity in degrading 5-fluorouracil; however, it is not necessary the most optimized form for photocatalytic degradation of other contaminants.