Solar Photocatalytic Degradation Of Phenols Wastewater With Ag/P3HT@TiO2 Nanocatalysts

• Main Authors: CHIU,PEI-SHAN, 邱沛珊
• Other Authors: KUO,WEN-SHIUH
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/58842591209223215465

碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 105 === Solar Ag/P3HT(Poly 3-hexylthiophene)@TiO2 photocatalytic degradation of phenols (phenol & 4-CP) wastewater was investigated in this study. Nano-photocatalysts Ag/P3HT@TiO2 composite was prepared by a novel partial shell-core method and photo-reduction method. The physical and chemical properties of Ag/P3HT@TiO2 nano-particles were characterized by Flame Atomic Absorption Spectrometry (AA), Scanning Electron Microscope (SEM), X-ray Energy Dispersive Spectrometer (EDS), X-ray diffraction (XRD), and UV/VIS Diffuse Reflectance Spectroscopy (UV/VIS DRS). The results showed that a 60-80% of the noble metal (Ag0) was deposited on the surface of TiO2 photocatalyst and the silver can be deposited onto the TiO2 surface in 15 to 30 minutes. The images of SEM showed the particle size of Ag/P3HT@TiO2 and TiO2 nano-particles with a similar range of 12-20 nm. The analysis of EDS confirmed that the molecule of P3HT and Ag with a desired content existed in the Ag/P3HT@TiO2 composite. Moreover, the results of XRD indicated the crystal pattern of TiO2 still presented mainly anatase form in Ag/P3HT@TiO2 composites. The spectrum of UV/VIS DRS showed that Ag/P3HT@TiO2 composites were much more responsive to visible light than TiO2. The higher the P3HT and Ag content, the more the absorption in the band of visible light. Using composition of the optimal Ag(0.05%~0.15%)/P3HT(0.5%)@TiO2 nanocatalysts, with catalysts of 0.5 g/L, a light irradiation of 500 W/m2 and a reaction time of 120 min could reach 79%~83% and 90%~92% efficiency of the abs@λmax reduction and 90%~93% and 99% efficiency of degradation, for phenol and 4-CP wastewater, respectively. Also the abs@λmax reduction efficiency of phenols wastewater could increase 9.15% (120 min) and 14.63% (90 min) for phenol and 4-CP wastewater, respectively as O2 aeration rate increased from 0 L/L/min to 0.5 L/L/min, which could contribute the overall reaction. If the photocatalytic experiment is carried out in the absence of oxygen (aeration N2) in the wastewater, the electrons can not react with enough oxygen to reduce the generation of superoxide radical, resulting in the organic pollutants in the wastewater can not be completely decomposed, so the appropriate provision of dissolved oxygen in the wastewater to aid the photocatalytic oxidation reaction. Moreover, the abs@λmax reduction rate efficiency of phenols wastewater could increase 3.46 and 4.49 times for phenol and 4-CP wastewater, respectively as light irradiation increased from 250 to 750 W/m2; the abs@λmax reduction efficiency of phenols wastewater could increase 17.05% and 7.2% for phenol and 4-CP, respectively as wastewater temperature increased from 15 °C to 25 °C, when the wastewater temperature increased to 35 °C, the degradation efficiency of wastewater promoted slowly. Based on the results, increasing the light irradiation can accelerate the generation of electrons and holes, thus accelerating the formation rate of hydroxyl radicals, and promoting the oxidation reaction. Appropriate increasing wastewater temperature could contribute to increase the frequency of collision between molecules and molecules, which is beneficial to improve the photocatalytic efficiency. However, the wastewater temperature effect is slowed down under fixed light intensity. With the assistance of Fresnel lens in the solar photocatalytic degradation of phenols wastewater could greatly enhance the degradation rate of phenols wastewater. The feasibility of photocatalytic technology using the composite nanocatalysts synthesized in this study was obvious. On the other hand, the photocatalytic efficiency of using solarlight as the light source was promoted, which can significantly save the operation cost . Based on the results obtained in this study, using the noble metal-Ag and P3HT (Poly 3-hexylthiophene) to modify the TiO2, can improve the TiO2 can only absorb ultraviolet light and electron-hole pairs of easy to re-combination. In this study, the partial shell-core type Ag/P3HT@TiO2 composite nanocatalysts can promote the photocatalytic degradation the difficult to decompose organic wastewater such as phenols wastewater and practical application of the increase, by the assistance of Fresnel lens in the actual solar light source. Keywords：partial shell-core type P3HT/TiO2, photocatalysis, phenols wastewater, phenol, 4-chlorophenol, Fresnel lens