- 學位論文
以不同晶相之二氧化鈦光觸媒催化分解酚
Use of Titanium Dioxide Catalysts with different crystallines for the Photodegration of Phenol in Aqueous Solutions
摘要
近年來因工業的高度發展，造就大量難分解的人工合成有機物，其成分複雜且不易被一般微生物代謝分解，一旦任意排放至自然環境中，不僅不易被微生物代謝分解，甚至引起生物積蓄作用，必定會對生態環境帶來相當大的衝擊。其中酚及其化合物在工業與日常生活中應用非常廣泛，在化學反應過程中，會形成相當穩定的化合物。由於這些污染物會累積在生物體內，殘留在環境中的時間很長，且毒性高具有致癌性，會破壞生態及人體健康。 本實驗以溶膠凝結法(Sol-gel)製備具有Aanatase相與Rutile相TiO2觸媒，並以高壓汞燈(400W)做為光降解酚水溶液中之光源，並藉由改變觸媒濃度添加量 (0 g~1.5g)、初始酚濃度(0.1 mM~1.05 mM)、pH值改變(pH4~pH10)等條件進行比較性實驗，來探討光觸媒降解過程中的變化，並與商用型Degussa P-25觸媒做光催化降解效果比較。利用XRD、UV-Vis與SEM等分析儀器分析Sol-gel製備Anatase相與Rutile相觸媒兩者晶相、吸收波長等差異性，由實驗結果發現在TiO2/UV 系統中若添加過多觸媒則會因遮蔽效應而使得光催化效率的降低，且由實驗觀察出具備Anatase相觸媒與商用型P-25觸媒兩者在降解酚濃度的趨勢非常的相似，酚化合物濃度會在30 min內快速降低，而30 min後的降解速率則逐漸趨向線性呈現，並由降解實驗結果可得知，以商用型P-25觸媒的解效率為佳(C0=0.47mM 0.5g TiO2)，此外單一晶相觸媒光催化效率並非是最佳，而是Anatase與Rutile混和的晶相降解效率較佳。
並列摘要
The development of industrialization contributes in generating great quantity of synthesized organic matters. The composition of those is usually complicated and difficult to decompose. That will result in the environmental pollutants if those matters are discharged irregularly. In addition, it may cause bio-accumulation since the compounds might be troublesome for microorganisms. Among of those matters, phenol and its derivates characterized with toxicity for human health are common chemicals utilized in the industrial production. Therefore, a promising method applied for dealing such chemicals is required. In the present work, anatase type and rutile phase type TiO2 were prepared by sol-gel procedure. Phenol was degraded using high-pressure mercury light (400W). Various parameters like the dosage TiO2 (0 g~1.5g), initial phenol concentration (0.1mM~1.05mM), pH value (pH4 ~ pH10)were changed in order to understand the process of degradation and compare with Degussa P-25. The physical properties, such as a crystalline size, band gap, etc., were characterized by XRD, UV-Vis spectra analyses. Sol-gel prepared TiO2 and its photocatalytic activity for phenol degradation were investigated. The experimental results indicated that photodegradation of phenol with TiO2 over dosage causes light shielding and the photocatalystic efficiency decrease. In addition, the effect of crystalline structure on phenol photocatalysric degradation was investigated by using the prepared TiO2 as well as commercial Degussa P-25. In this system, the concentration of phenol decreases quickly within 30min, but then becomes slowly and stable decrease. For the Photocatalytic reaction of phenol, the best photodegradated efficiency was Degussa P-25. The results showed that the Photocatalytic activity of prepared TiO2 is lower than that of the Degussa P-25 and a synergistic effect between anatase and rutile form of TiO2 was found for the Photocatalytic oxidation of phenol.