多數催化劑中以二氧化鈦(TiO2)最為廣泛使用,但需要以紫外光照射光觸媒才能產生較大的效益,且電子電洞對的再結合亦是問題之一。奈米碳管(Carbon Nanotube, CNT)具有高強度之機械性質及高化學穩定性,所以其複合材料CNT/TiO2更常被用來進行光催化水和空氣中的污染物。本研究以二氧化鈦添加多壁奈米碳管(MWCNT)及單壁奈米碳管(SWCNT)於觸媒之中,以不同添加量(0.1、0.2、0.5 g)針對亞甲基藍(Methylene Blue)之降解,比較CNT/TiO2光觸媒的光催化效果,並使用不同的實驗因子如光照時間、光源、批次或循環系統等來評估此光觸媒對亞甲基藍光解效率之差異,並找出最佳條件對五氯酚(Pentachlorophenol)進行降解測試。 研究結果顯示在X射線繞射分析儀(XRD)分析方面,確認本研究所採用之觸媒為銳鈦礦型為主的優勢晶體。而經由掃瞄式電子顯微鏡(SEM)之結果顯示MWCNT及SWCNT是以不同的管狀結構存在,添加的量不同也使得TiO2表面產生不同的型態;由傅立葉紅外線光譜儀(FT-IR)分析結果顯示當添加0.2 g MWCNT時,會產生最強的氫氧自由基鍵結;另外在光催化效率中發現以添加0.2 g MWCNT/TiO2於自然日光光照8 小時降解率(99 %)最高;添加0.2 g MWCNT/TiO2於氙燈光照8小時降解率為85 %;而在可見光下以添加0.2 g MWCNT/TiO2的降解率(70 %)最高;於循環光照處理中以添加0.5 g MWCNT/TiO2的降解率(18 %)較好;而以最佳條件處理為添加0.2 g MWCNT/TiO2進行五氯酚降解其降解效率可達61 %。
Titanium dioxide (TiO2) is one of the most widely used catalysts. However, it requires ultraviolet light to enhance its efficiency. The recombination of electron and hole is one of the problems. Carbon nanotubes (CNT) has the mechanical properties of high strength and high chemical stability; so, the composite materials of CNT/TiO2 were common used for the photocatalysis of water and air pollutants. In this study, titanium ioxide doped with Multi-Walled Carbon Nanotubes (MWCNT) and Single-Walled Carbon Nanotubes (SWCNT) using different amounts (0.1, 0.2, 0.5 g) were prepared for the degradation of methylene blue. Different experimental factors including exposure times, light sources, batch or circulatory systems were conducted to evaluate the photocatalytic efficiency of methylene blue solutions. The best experimental parameters were applied to study the degradation of pentachlorophenol (PCP). Degradation rates, toxicity, and chloride ion concentration were also investigated. The results of X-ray diffraction (XRD) analysis confirmed that the catalyst used in this study was anatase as the major crystal. The results of scanning electron microscopy (SEM) showed the existence of MWCNT and SWCNT in various tubular structures. Different types of TiO2 surface were showed on the different amounts used. Fourier transform infrared spectroscopy (FT-IR) analysis showed that 0.2 g MWCNT will produce the most hydroxyl radicals. The highest photocatalytic efficiency (99%) was found using 0.2 g MWCNT/TiO2 under 8 hours of natural daylight exposure. With 0.2 g MWCNT/TiO2 under xenon lamp reached 85% of degradation rate in 8 hours. Using visible light and 0.2 g MWCNT/TiO2 showed 70% of degradation rate. In the circulation treatment system, only 18 % of degradation rate was reached using 0.5 g MWCNT / TiO2. The best experiment conditions with 0.2 g MWCNT/TiO2 were used, and the degradation efficiency of PCP was up to 61%.
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