大部分人們約有80%的時間待在室內，因此，室內空氣品質的重要性越來越高。室內空氣汙染物主要來自於揮發性有機物，其中甲苯極具代表性。甲苯主要汙染源來自油漆塗料、家具、消毒劑和化學藥劑中。甲苯本身具高毒性、致癌性且能長時間存在於空氣中，因此，有效去除室內空氣中甲苯的技術十分重要。
在移除室內之揮發性有機汙染物技術中，以光觸媒氧化法為主要選項，因為這方法能使揮發性有機汙染物轉換成二氧化碳與水，不會對環境造成二次汙染。最常使用的光觸媒為二氧化鈦，因為其成本低且具高穩定度、良好的光催化能力。但因二氧化鈦之吸收波段屬於紫外光範圍，不利將其使用於室內，因此需藉由改質方法來改善二氧化鈦對於可見光之利用效率。
本研究將透過摻雜硫、氮、石墨烯於二氧化鈦中以溶熱法製作成複合奈米光觸媒材料，以改善二氧化鈦本身吸收可見光之限制。從UV-visible 光譜的結果可得知摻雜硫、氮、石墨烯於二氧化鈦中可增加可見光的吸收強度。根據XPS、FTIR、Raman 的分析結果得知二氧化鈦複合光觸媒表面具有含氧官能基鍵結且具有化學缺陷結構。從XRD、SEM的結果得知摻雜還原氧化石墨烯會減少二氧化鈦的晶體尺寸。在光催化活性實驗中以含0.1wt%還原氧化石墨烯之硫氮摻雜二氧化鈦具有最佳的光催化活性，其轉化率達58％，添加過多的還原氧化石墨烯會造成光遮蔽效應，1wt%rGO表之轉化率僅為16％。以0.1wt%rGO光觸媒進行不同操作參數試驗中，1%RH時之轉化率最高為87％，提升水氣濃度至80％RH導致轉化率下降至44％，其可能是因為水氣與甲苯產生競爭吸附；提高操作溫度至45℃時可使轉化率增加至74％，是由於增加分子之間的碰撞機會以及吸附於表面的水減少；增加甲苯的進流濃度到4 ppm則造成轉化率下降為50％，但反應速率增加。在Langmuir-Hinshelwood之7個吸附模式中得到模式4最適合本研究結果。從操作參數與動力學試驗結果指出水氣對於甲苯光催化活性之影響遠大於溫度，因為甲苯和水氣會產生競爭吸附。根據FTIR 測試中發現甲苯在光催化過程中會生成苯甲醇、苯甲醛、苯甲酸，最後生成水和二氧化碳。

Most people spend about 80% of their time indoors, the indoor air quality has received much attention. Indoor air pollutants mainly come from volatile organics, which toluene is one of the most representative. The main source of toluene contamination comes from paints, furniture, disinfectants and chemicals. Toluene is highly toxic, carcinogenic and long persistence in indoor environment. Therefore, it is important to effectively remove toluene in the indoor air.
In the technology of removing indoor volatile organic pollutants, photocatalytic oxidation is one of the main methods. Because it can convert volatile organic pollutants into carbon dioxide and water, it will not cause secondary pollution to the environment. The most commonly used photocatalyst was TiO2 due to its low cost, high stability, and good photocatalytic capability. However, since the absorption band of TiO2 belongs to the ultraviolet region, it is not suitable for indoor. Therefore, it is necessary to improve the utilization efficiency of titanium dioxide for visible light by a modification method.
In this study, the photocatalysts were prepared through doping sulfur, nitrogen and graphene in TiO2 by a solvothermal method to improve the visible light absorption of TiO2. From the results of UV-visible spectroscopy, it can be seen that the doping of sulfur, nitrogen, and graphene in TiO2 increases its absorption intensity of visible light. According to the analysis results of XPS, FTIR, and Raman, it is known that synthesis of the rGO/S0.05N0.1TiO2 composite produces oxygen-containing functional group bond and chemical defect structure. From the results of XRD and SEM, it is known that doped reduced graphene oxide reduces the crystal size of TiO2. In the photocatalytic activity experiment, 0.1wt%rGO/S0.05N0.1TiO2 has the best photocatalytic activity and adding too much reduced graphene oxide will cause a light shielding effect. In operating parameters tests, the increase in water vapor concentration resulting in a decrease in the conversion rate may be due to the competitive adsorption of water vapor and toluene; the increase in operating temperature may increase the conversion rate due to the increased chance of collisions between molecules and the reduction of water adsorbed on the photocatalyst surface. Increasing the influent concentration of toluene results in a decrease in the conversion rate. Langmuir-Hinshelwood model 4 is best suited to this study, the water vapor has more effect on the toluene conversion than the temperature. According to the FTIR test, toluene oxidation has been found to generate benzyl alcohol, benzaldehyde, and benzoic acid during the photocatalytic process, and finally to produce water and carbon dioxide.

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