以天然多醣類製備光觸媒ZnO及其光催化特性之探討; Preparation and Photocatalytic Activity of ZnO Using Natural Polysaccharides as Templates.

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Title:	以天然多醣類製備光觸媒ZnO及其光催化特性之探討;Preparation and Photocatalytic Activity of ZnO Using Natural Polysaccharides as Templates.
Authors:	李俊福
Contributors:	環境工程研究所
Keywords:	多醣類;氧化鋅;光催化劑;表面改質;polysaccharical;ZnO;surface modification;photocatalyst;環保工程
Date:	2010-08-01
Issue Date:	2011-07-12 14:17:04 (UTC+8)
Publisher:	行政院國家科學委員會
Abstract:	事業廢水的處理在目前仍為環境工程界極具挑戰性的課題。依現今發展的科技成果，為解決嚴重的廢水問題已有許多技術被開發出來，但至目前為止這些方法可能都不盡完善，因其會產生許多後續再處理問題。近年來興起使用觸媒來幫助處理廢水，觸媒運用得當，可以以最少藥劑達到處理的最佳效果。最常做為研究題材的光觸媒材料，以二氧化鈦及氧化鋅為主，不過又以二氧化鈦居多，因為二氧化鈦有較佳的光化學穩定性與高處理效率。氧化鋅與二氧化鈦雖然有相似的光激發躍遷能階，但二者相較，氧化鋅可吸收光波範圍較廣，在可見光激發下，可以比二氧化鈦吸收較多光子；另外，氧化鋅在鹼性條件下對某些染料降解效率顯然較二氧化鈦為佳，而氧化鋅也兼具價格便宜、毒性較低與反應基質干擾較少等優點，故氧化鋅光催化特性的探討仍深具研究價值。文獻常被應用於製造氧化鋅光催化劑的方法有雷射剝離法、水熱法、溶膠-凝膠法與噴霧熱解法等，而每種製備方法皆有其缺點及待改進之處。基於上述前提，本研究乃選取成本低廉，對環境友善且廣泛存在於農畜業廢棄物中之多醣體 (如纖維素、甲殼素等)為基質，預期以三年時間將其表面進行衍生化改質並以脫水熱解及加熱裂解法合成氧化鋅並探討其光催化降解有機污染物的特性。全程研究內容首先探討天然多醣體與重金屬鋅之親和力以做為後續改質(衍生化)的依據，接續將多醣體以不同方式進行接枝與交聯反應以提昇金屬鋅和多醣體衍生物之錯合程度，關鍵步驟則依據配位與有機化學學理的推論並藉助製藥業使用成熟的鍛燒熱解技術來裂解有機金屬聚合物以製備氧化鋅，多醣體衍生物及氧化鋅均將以TEM、SEM、NMR、X-ray、LRSS、RHEED 等精密儀器鑑定其表面官能基理化特性。氧化鋅對特定污染物之光催化能力探討將以完備之實驗程序來完成，其光催化效率將與傳統化學合成法合成之氧化鋅來進行比較，最後由多醣類及其衍生物所製備的氧化鋅和二氧化鈦間之光催化污染物比較亦列為研究重點之一，其他光催化綜合效應的探討亦併入本計劃研究內容中。基於完整文獻資料的蒐集與彙整，結合本團隊歷年累積的研究經驗和初步研究成果的展現，以及依據基礎配位與有機化學學理的合理推論，我們深信本研究以天然多醣體合成之氧化鋅其光催化特性的了解是可以被預期的。 How to treat industrial wastewater is an important issue in the present day. In order to reduce environmental pollution, many kinds of technologies for treating various wastewaters have been developed. However, the developed technologies are still deficient for completely solving all problems up to now. Frequently, photocatalyst is used to increase removal efficiencies of contaminants in the recent years. This way could reduce the addition of chemical reagent to wastewater. The photocatalysts such as titanium dioxide (TiO2), and zinc oxide (ZnO) are generally applied to examine the results of contaminant removal ratios. Because titanium dioxide possesses the higher photostability and the better photodegradation efficiencies for contaminants, it is most commonly selected as photocatalysts. Photoluminese exited level of zinc oxide is similar to that of titanium dioxide. However, zinc oxide possesses a relatively wider range of absorbed wavelength, leading to greater photon adsorbed. In addition, zinc oxide in base solution to photodegrade dye can produces the higher efficiency. Also, zinc oxide has the advantages of economy, low toxicity, and low interference. Moreover, photocatalyst, zinc oxide, to photodegrade organic compounds needs to be studied further. Synthesis method of photocatalyst includes laser ablation, hydrothermal, sol-gel and spray pyrolysis. Some of disadvantages for these methods need to be improved. In this study, the dehydration condensation reaction and hydrothermal method was used to produce the photocatalyst of zinc oxide. Polysaccharide (e.g. cellulose and chitosan) was used as the reactant. The project of photodegrading organic compounds will be finished for three years. First, the affinity of natural polysaccharides for zinc was studied to be a reference of following derivatization study. Then, various graft copolymerization and gelation process will be applied to increase complex ability of the derivative between polysaccharide and zinc. The key point is pyrolysis of high temperature calcinations to synthesize zinc oxide based on the ligand theory. The surface characteristics of derivative and oxide zinc are analyzed using TEM, SEM, NMR and X-ray. The photodegradation efficiency of oxide zinc obtained from the proposed method is compared with that from the traditional method. Finally, the difference in photodegradation efficiency between the zinc oxide synthesized via polysaccharide and its derivative and titanium dioxide are also discussed. 研究期間：9908 ~ 10007
Relation:	財團法人國家實驗研究院科技政策研究與資訊中心
Appears in Collections:	[Graduate Institute of Environmental Engineering ] Research Project

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