Photocatalytic degradation of formaldehyde in indoor air by graphene/S N/TiO2 nanocomposite photocatalyst using a fluorescent lamp

摘要

Nowadays people spend more than 80% of time in indoor environments in modern social way of life Therefore indoor air quality should be paid more attention due to the indoor air pollutants impact on human health through directly chronic inhalation Formaldehyde most often appears in the indoor environment where can be escaped from furnishing cleaning agents and paints And it has been confirmed to be carcinogenic to the human body Thus the elimination of formaldehyde is essential for improving air quality Indoor environmental conditions are usually room temperature high humidity and often with low concentration pollutants which are not easy to collect Fortunately photocatalytic oxidation is a suitable technology with low-cost no secondary pollution and low energy consumption Titanium dioxide is most widely used in photocatalytic applications However titanium dioxide absorption band is mostly in the range of ultraviolet light this drawback limits the removal of indoor air pollution by titanium dioxide In this study the photocatalysts were prepared through doping sulfur nitrogen and graphene in titanium dioxide by a solvothermal method to improve the visible light absorption of titanium dioxide The UV-visible absorption spectrum indicates that doping of S N and graphene can improve visible light absorption intensity and reduce the band gap The XPS FTIR and Raman spectra show that synthesis of the rGO/S0 05N0 1TiO2 composite produces new chemical defect and bonding by introducing oxygen-containing functional groups further enhances the photocatalytic effect The XRD SEM TEM and BET results show that crystallite sizes of rGO/S0 05N0 1TiO2 are reduced by introduction of graphene sheets The TiO2 particles are attached to the rGO surface and interposed between the rGO layers promoting an increase of specific surface area rGO can enhance the overall photocatalytic efficiency due to its excellent electron transport capacity and high specific surface area but excess rGO could shield the light In this study 0 1 wt% rGO is the best doping amount The reaction rate of formaldehyde is mainly affected by water vapor concentration Too little water vapor may reduce the generation of hydroxyl radicals; Too much water vapor may cause competitive adsorption of water with formaldehyde Langmuir-Hinshelwood model 4 is best suited to this study the water vapor has more effect on the formaldehyde conversion than the temperature under building room environment Regarding the conversion mechanism was verified by FTIR formaldehyde may be first converted to formate then carbon monoxide and finally carbon dioxide

獎項日期	2017 6月 20
原文	English
監督員	Hsin Chu (Supervisor)