Photocatalytic Mechanisms and Pathways of metronidazole Antibiotic in aqueous solutions over modified metal oxide catalysts: Doctoral Thesics- Major: Chemical and Material Engineering

長庚大學化工與材料工程學系

博士論文

Department of Chemical and Materials Engineering

Chang Gung University

Doctoral Thesis

利用改質之金屬氧化物觸媒光催化水溶液中甲硝唑

抗生素之機制與降解路徑

Photocatalytic Mechanisms and Pathways of

Metronidazole Antibiotic in Aqueous Solutions over

Modified Metal Oxide Catalysts

指導教授：莊瑞鑫 博士

Advisor: Ruey-Shin Juang, Ph.D.

研究生：陳梅蓮

Graduate Student: Tran Mai Lien

中華民國 109 年 01 月

January 2020

Chang Gung University

Recommendation Letter from the Thesis Advisor

This thesis is by TRAN MAI LIEN (Author) of the graduate

program in Department of Chemical and Materials Engineering, entitled:

Photocatalytic Mechanisms and Pathways of Metronidazole Antibiotic

in Aqueous Solutions over Modffied Metal Oxide Catalysts, which is

written under my supervision, and I agree to propose it for examination.

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ACKNOWLEDGMENTS

First and foremost, I would like to express my sincere gratitude to my advisor Prof. Ruey￾Shin Juang for his patience, encouragement, and enthusiasm during my Ph.D. study. His guidance

and suggestions helped me with all the steps of my research.

I would like to thank Chang Gung University (CGU) for the scholarship giving me a chance

to study in Taiwan, a beautiful island. Financial support for this work through grants from the

Ministry of Science and Technology and the Chang Gung Medical Foundation, Taiwan is greatly

appreciated.

My sincere thanks also go to professors in the Department of Chemical and Materials

Engineering helping me in studying all courses, sharing the knowledge, and encouraging me during

the time I study here.

I also would like to thank the Industrial University of HoChiMinh City for continuous

supporting me during a four-year study in Taiwan.

I am grateful to Ph.D. student Chun-Chieh Fu, labmates, and other students of CGU for their

help and advice for my experiments.

I also wish to thank Vietnamese friends in CGU who always side by side with me to share

all the difficulties and troubles during my study time.

Last but not least, my sincerest thanks to my family: my parents and my sister for their love

and encouragement to live stronger and approach to self-improvement.

iv

摘要

甲硝唑(Metronidazole, MNZ)是最常見的抗生素之一，本論文首先使用兩種具有潛力

之催化劑 TiO2和 ZnO 光降解去除 MNZ。通過應用中央複合設計(Central composite design,

CCD)、反應表面法(Response surface methodology, RSM)和中間產物分析對光降解過程進

行優化比較。在 20oC 下照射 60 分鐘 100 W 紫外光(UV)後發現，最佳之光降解條件為在

pH 6.0 下使用 1.5 g L-1 TiO2（去除 86%之 50 mg L-1 MNZ）和在 pH 9.5 下使用 0.5 g L-1 ZnO

（去除 60.3%之 30 mg L-1 MNZ）。此外，無論是 TiO2/UV 或 ZnO/UV 系統，都存在的諸

如氫氧根自由基(·OH)，電子洞(h

+

)和超氧自由基(·O2

-

)等活性基參與氧化 MNZ，其中電子

洞和超氧自由基起著至關重要的作用。通過液相層析飛行質譜儀(LC-QTof/MS)分析確認

之 10 種主要降解中間產物，上述兩個系統中有 5 種相同，顯示可能由於不同處理系統及

條件而產生不同之降解中間產物，導致降解路徑(Degradation pathways)之變化。

使用光降解效率較高之 TiO2 討論不同溶液成份對 MNZ 光降解作用之影響，包括陰

離子（Cl-、SO4

2-、NO3

-、HCO3

-及 H2PO4），陽離子（Ca2+、Mg2+及 Fe

3+），天然有機物

（腐植酸），以及藥物賦形劑（葡萄糖）等。在這些溶液成份中，H2PO4

-、Fe3+及腐植酸

(Humic acid)的存在導致 MNZ 降解效率從 20%降到 60%，而葡萄糖的存在將降解速率提

高了近 3 倍。經由中間產物之檢測表明，（1）當葡萄糖降解時，葡萄糖會通過 MNZ 及其

中間產物與其他有機物之副反應而增加 MNZ之去除率；（2）腐植酸可激活電荷轉移，導

致產生不同之光降解產物；（3）Fe3+在光吸收方面與 MNZ 相互競爭；（4）HPO4

-通過與

TiO2相互作用而不改變途徑來減慢 MNZ 之降解速度。

使用 TiO2 光降解系統應用於 MNZ 和另一種抗生素安莫西林(Amoxicillin, AMX)之混

合物溶液，以探討降解競爭和路徑之變化。儘管 TiO2/UV 系統釋放之所有活性氧化物質

（·OH、·O2

-及 h

+）均可攻擊 AMX分子，但·OH在 MNZ降解中表現出微弱之攻擊能力；