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  • 學位論文

合成奈米銀複合光觸媒降解水中壬基苯酚及利用Microtox法評估毒性效應

Photocatalytic Degradation of Nonylphenol in Aqueous Solution by Prepared Ag/TiO2 Nanocomposite Photocatalyst and Assessment of the Acute Toxicity from Microtox Assay

指導教授 : 王文裕 王順成
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摘要


本研究以溶膠凝膠法(Sol-Gel Method) 製備奈米級TiO2及Ag/TiO2複合光觸媒材料,利用不同製溶劑及添加金屬銀改善TiO2材料特性,研究中探討不同燒結溫度、添加金屬銀比例、污染物濃度多寡及光觸媒材料添加量等條件下對光催化之影響,得知降解壬基酚的最佳操作參數。製備完成之光觸媒利用TGA、XRD、BET、HPPS及SEM加以分析探討。 TGA分析顯示利用不同溶劑製備之TiO2熱穩定溫度介於500℃-600℃而複合Ag/TiO2熱穩定溫度提升600℃-650℃;XRD分析顯示TiO2及Ag/TiO2複合光觸媒材料於未經熱處理已有少量銳鈦礦晶相,而甲醇、乙醇、丙醇、異丙醇及丁醇最佳煅燒溫度為700℃、600℃、600℃、800℃及500℃,Ag/TiO2複合光觸媒於700℃以上仍保有銳鈦礦晶相;SEM分析顯示乙醇及異丙醇溶劑較適合用於製備TiO2,因此兩種溶劑製備TiO2時有粒徑小及顆粒均勻等優點,而添加金屬銀複合材料能降低顆粒大小;BET分析顯示乙醇比表面積相較於其他醇類來得高,則複合金屬銀會使TiO2表面被覆蓋使比表面積降低;HPPS分析顯示高溫煅燒500℃以上能有效去除材料中不純物或雜質,使水中團聚作用減少。 光催化試驗結果得知,光催化最佳壬基酚濃度為15 ppm及0.5 g的光觸媒添加量。而TiO2降解水中壬基酚之效果為乙醇以500 ℃製備者最佳,其次為甲醇700 ℃及異丙醇500 ℃,去除率分別為43%、39%及39%,可見鈦酸四丁酯於甲、乙及異丙醇中能有效分散,讓水解聚合反應更完整,顆粒較小,且比表面積增加,並增進光催化活性。Ag/TiO2複合材料降解壬基酚以3%複合銀材料,煅燒溫度300℃、500℃及700℃材料皆大於其他三種mole%銀材料,而500℃可有效去除72%的壬基酚濃度。 Microtox法檢測毒性分析結果為光降解壬基酚去除率,雖影響其毒性效應,但於降解過程產生之中間產物亦可能使毒性上升,隨光降解時間增加,其毒性有緩慢下降趨勢。

並列摘要


In this study, nanomaterials TiO2 and nanocomposite Ag/TiO2 photocatalyst had been prepared by sol-gel method with addition of silver. The effect of different solvent, Ag/TiO2 molar ratios and annealed temperatures on the properties of nanocomposite photocatalyst material has been discussed. The samples were characterized by various analytical instruments, such as thermogravimetry analyzer (TGA), X-ray diffractometer (XRD), low temperature N2 adsorption (BET), field emission scanning electron microscopy (FE-SEM) and high performance particle sizer (HPPS). The photocatalytic activites of the prepared samples were evaluated by Nonylphenol degradation and MicrotoxR toxicity. The analysis results of TGA revealed that the steady state temperature for crystal phase transition from anatase to rutile is 500-600℃ for TiO2, but the nanocomposite Ag/TiO2 improves the steady state temperature up to 600-650℃. The analysis results of XRD revealed that nanocomposite Ag/TiO2 has a significance of phase transition from anatase to rutile in comparison with pure TiO2 at comparable temperature. The optimum calcination temperature for TiO2 photocatalysts prepared with methanol, ethanol, propanol, isopropanol and butanol was 700℃, 600℃, 600℃, 800℃ and 500℃, respectively, but all of the Ag/TiO2 composite photocatalyst retains anatase phase at temperature above 700℃. The SEM pictures revealed that ethanol and isopropanol was more suitable for the preparation of TiO2 with smaller and uniform particles. The surface of Ag/TiO2 composite is covered with metal silver so that the specific surface area decreased. BET surface area of composite photocatalyst prepared with ethanol is higher than other type of alcohols. HPPS analysis results showed that the photocatalyst calcined at 500℃ can reduce agglomeration in water. Photocatalytic reaction results showed that the best dose of photocatalyst was 0.5 g for 15 ppm of nonylphenol. The photocatalytic reactions of nonylphenol with TiO2 prepared by different types of alcohol were accomplished. The degradation ratio was 43%, 39% and 39% for ethanol, methanol and isopropanol, respectively. Photocatalytic degradation ratios of nonylphenol by Ag/TiO2 composite with silver dose of 3 mole % and calcined at different temperatures (300℃, 500℃ or 700℃) were higher than the ratios by Ag/TiO2 composite with silver dose of 1%, 2% and 4%. MicrotoxR analysis results indicated the toxic of nonylphenol was degraded by photocatalysis, but the toxic increased at initial photocatalysis stage. It was proposed to generation of more toxic intermediates at initial photocatalysis stage. Toxic effects decline as photocatalytic reaction time increased.

並列關鍵字

nanocomposite sol-gel nonylphenol Photocatalytic Microtox

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