| Summary: | 碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 104 === Solar P3HT(Poly 3-hexylthiophene)/TiO2 photocatalytic degradation of phenols (phenol & 4-CP) wastewater was investigated in this study. Nano-photocatalysts including P3HT(0.5%)/TiO2 and P3HT(1.0%)/TiO2 composites were prepared by a novel partial shell-core method. The physical and chemical properties of P3HT/TiO2 nano-particles were characterized by Scanning Electron Microscope (SEM), X-ray Energy Dispersive Spectrometer (EDS), X-ray diffraction (XRD), and UV/VIS Diffuse Reflectance Spectroscopy (UV/VIS DRS). The images of SEM showed the particle size of P3HT/TiO2 and TiO2 nano-particles with a similar range of 20-50 nm. The analysis of EDS confirmed that the molecule of P3HT with a desired content existed in the P3HT/TiO2 composite. Moreover, the results of XRD indicated the crystal pattern of TiO2 still presented mainly anatase form in P3HT/TiO2 composites. The spectrum of UV/VIS DRS showed that P3HT/TiO2 composites were much more responsive to visible light than TiO2. The higher the P3HT content, the more the absorption in the band of visible light.
Response surface methodology (RSM) with a 3*3 experimental design of Box-Behnken, ANOVA and a 3-1-1 model of artificial neural network (ANN) were applied to assess the effect of critical process parameters ([catalyst], P3HT content, O2 aeration rate) on treatment performance in terms of phenols molecular degradation efficiency and TOC mineralization efficiency. Optimized reaction conditions were established: [catalyst]: 1.36 g/L, P3HT content: 0.5%, a O2 aeration rate of 1 L/L/min and a reaction time of 90 min for reaching a 95% efficiency of phenol degradation; For photocatalytic degradation of 4-CP wastewater: [catalyst]: 1.5 g/L, P3HT content: 0.5%, a O2 aeration rate of 0.275 L/L/min and a reaction time of 120 min for reaching a 90% efficiency of TOC mineralization.
Under the optimized reaction conditions, the degradation efficiency of phenols wastewater could increase 42.64% and 29.74% for phenol and 4-CP, respectively as light irradiation increased from 250 to 750 W/m2. The degradation efficiency of phenols wastewater could increased 13.29% and 12.09% for phenol and 4-CP, respectively as wastewater temperature increased from 15 to 35 oC. Accordingly, it was supposed that solar energy consisting of light energy and heat irradiation could have a synergistic effect on the P3HT/TiO2 photocatalytic reaction, especially with the assistance of Fresnel lens.
Moreover, it was found that the degradation efficiency of phenols wastewater increased basically as the dosage of photocatalyst increased. An appropriate presence of P3HT content and O2 supply rate were beneficial to solar photocatalytic process. The dosage of photocatalyst was considered as the most weight parameter of phenols degradation on the basis of ANOVA and ANN model analysis. On the other hand, TiO2 were almost coated by P3HT in the shell-core type of P3HT/TiO2 photocatalyst, leading to a lower shift rate of electrons and a lower photocatalytic efficiency of phenols wastewater than the partial shell-core type of P3HT/TiO2 photocatalyst. A 10% increase of the abs@λmax reduction efficiency of phenols wastewater would be found as partial shell-core type P3HT/TiO2 instead of shell-core type P3HT/TiO2 used in a photocatalytic reaction.
Based on the results obtained in this study, it was revealed that the partial shell-core P3HT/TiO2 photocatalysts could effectively adsorb and employ solar irradiation for the degradation of phenols wastewater successfully.
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