製備改質氮摻雜ZIF-67晶體應用於高級氧化程序移除有機染料

Synthesis of Modified N-doped ZIF-67 Crystals for Advanced Oxidation Processes for the removal of Organic Dye

康雅絜(YA-JIE KANG)

指導教授 ： 林義?

中原大學/工學院/化學工程學系/碩士(2022年)

https://doi.org/10.6840/cycu202201446

摘要

自十八世紀工業革命後，科技快速進步下促進了經濟發展，但也伴隨著對環境的破壞，其中水資源的汙染與缺水的問題日益嚴重，因此汙水處理技術成為了不可或缺的議題。在實際應用上以芬頓程序( Fenton Process)最廣泛使用，此程序有許多優勢，像是對於汙染物降解有高效效能、設備操作簡易等等，但在反應過程中會伴隨著二次汙染之問題，因此學者們致力於類芬頓程序( Fenton Prosess )的發展，又可稱做高級氧化程序(Advanced Oxidation Process, 簡稱AOPs)，高級氧化程序是以芬頓程序作為核心概念，使用異相觸媒取代芬頓程序中的均相觸媒，因此無難以分離的缺點及無二次污染的問題，且異相觸媒可對氧化劑保有高效之催化效能。近年來許多學者們將氧化劑改用過硫酸鹽來進行反應，其中所產生的硫酸根自由基(2.5~3.1 V)與傳統芬頓程序所產生的氫氧自由基(2.8 V)相比，有較高的氧化還原電位，其中硫酸根自由基能夠在更廣的pH值範圍中應用。

本研究以共沉澱法製備出ZIF-67晶體，藉由金屬有機配位沸石之高比表面積提高反應速率且過程中會添加單寧酸、聯胺進行改質，單寧酸可包覆ZIF-67晶體使其成為核殼結構，聯胺可提升金屬分散度及提高氮源，之後透過氮氣進行熱處理將金屬有機配位沸石轉換成碳材複合氧化鈷與金屬鈷，可更有效的與氧化劑進行反應，提升其降解效能。

另外本研究亦探討在催化過程中之操作參數及環境參數，例如:觸媒濃度、氧化劑濃度、環境酸鹼值以及抑制劑等。最終以操作參數，染劑濃度為10 ppm/10 ml，氧化劑PMS濃度為700 ppm/1 ml下有最佳降解有機汙染物之效能99.9 %。其中為了驗證本研究中主要之高氧化還原自由基，在實驗中加入抑制劑，可發現添加L-histidine、DMSO後降解效能大幅下降，且於EPR檢測中以TEMP作為捕捉劑，TEMP會與單線態氧形成TEMPO，能夠驗證本研究確實存在單線態氧。於再生實驗中可以觀察到此觸媒仍有優異之降解效能且具有磁性利於後續回收使用，由此可證，本研究所製備出觸媒具有高效且可回收再利用之優勢。

關鍵字

共沉澱法 ； 金屬鈷 ； 氮摻雜ZIF-67 ； 高級氧化程序 ； 過硫酸氫鉀

並列摘要

Since the industrial revolution in the 18th century, the rapid progress of science and technology has promoted economic development, but it has also been accompanied by damage to the environment. Among them, the pollution of water resources and the problem of water shortage have become increasingly serious. Therefore, wastewater treatment technology has become an indispensable issue. In practical applications, the Fenton Process is the most widely used treatment. This process has many advantages, such as high efficiency for pollutant degradation, simple equipment operation, etc., but it will cause secondary pollution during the reaction process. Therefore, scholars are committed to the development of Fenton-like Process, which can also be called Advanced Oxidation Processes (AOPs). The Advanced Oxidation Processes takes the Fenton Process as the core concept and uses a heterogeneous catalyst to replace the homogeneous catalyst in the process, so there is no disadvantage of difficult separation and no secondary pollution problems, and the heterogeneous catalyst can maintain high efficiency for oxidants the catalytic performance. In recent years, many scholars have switched the oxidant to persulfate for the reaction. Compared with the hydroxyl radical (2.8 V) generated by the traditional Fenton Process, the sulfate radicals (2.5~3.1 V) produced have higher redox potential, where sulfate radicals can be applied over a wider pH range.
In this study, ZIF-67 crystal was prepared by co-precipitation method. The high specific surface area of metal organic coordination zeolite increased the reaction rate, and tannic acid and hydrazine were added for modification during the process. Tannic acid coat ZIF-67 crystal to make it into a core-shell structure, and hydrazine can improve metal dispersion and increase nitrogen source. Then the metal organic coordination zeolite was converted into carbon composite cobalt oxide and metal cobalt by heat treatment with nitrogen, which could react with the oxidant more effectively and improve its degradation efficiency.
In addition, this study also discusses the operating parameters and environmental parameters in the catalytic process, such as catalyst concentration, oxidant concentration, environmental pH and inhibitors. Finally, according to the operating parameters, the best degradation efficiency of organic pollutants is 99.9% while the dye concentration is 10 ppm/10 ml, and the oxidant PMS concentration is 700 ppm/1 ml. Among them, in order to verify the main high redox free radicals in this study, an inhibitor was added in the experiment, and it was found that the degradation efficiency was greatly reduced after adding L-histidine and DMSO, and TEMP was used as a capture agent in the EPR detection. TEMP will form TEMPO with singlet oxygen, which can verify the existence of singlet oxygen in this study. In the regeneration experiment, it could be observed that the catalyst still had excellent degradation performance and was magnetic to facilitate subsequent recycling. This proves that the catalyst prepared in this study has the advantages of high efficiency and recyclability.

並列關鍵字

Co-precipitation ； Metallic cobalt ； Nitrogen-doped ZIF-67 ； Advanced Oxidation Processes ； Potassium persulfate

參考文獻

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