Title Page
Contents
요약문 8
Abstract 12
Chapter 0. Introduction 18
Chapter 1. Photocatalytic Degradation of Sulfathiazole (STZ) Using Micro-sized TiO₂ 23
1. Background study 23
1.1. Photocatalyst 23
1.2. Mechanism of TiO₂ 24
2. Materials and methods 28
2.1. Synthesis of TiO₂ photocatalyst 28
2.2. Characterization of catalyst 29
2.3. Photocatalytic performance test 30
3. Results and discussion 31
3.1. Characterization of TiO₂ catalyst 31
3.2. Removal of Sulfathiazole using TiO₂ photocatalyst 34
4. Conclusions 41
Chapter 2. Photo-degradation of microplastics using a UV/TiO₂/Oxidant system 43
1. Background study 43
1.1. TiO₂ disadvantage 43
1.2. Activation of oxidizing agents upon light irradiation 45
2. Materials and methods 51
2.1. Materials 51
2.2. Photocatalytic degradation of MPs 51
2.3. Field Emission-Scanning Electron Microscopy (FE-SEM) 53
2.4. Fourier Transform Infrared Spectroscopy (FTIR) 53
2.5. X-ray Photoelectron Spectroscopy (XPS) 54
3. Results and discussion 55
3.1. SEM analysis 55
3.2. Weight loss 61
3.3. FTIR analysis 62
3.4. XPS analysis 69
3.5. Mechanism of MP photodegradation 81
4. Conclusion 94
Reference 97
Table 1. Periodate radical generation mechanism under UV irradiation 48
Figure 1.1. Illustration of TiO₂ activation and radical production under UV irradiation. 25
Figure 1.2. Schematic diagram of a photoreactor. 31
Figure 1.3. (a) XRD pattern and (b) library search data of the synthesized TiO₂. 32
Figure 1.4. SEM images of the synthesized TiO₂ at different magnifications of (a, × 300) and (b, × 3.0k). 33
Figure 1.5. Particle size distribution of TiO₂ catalyst. 34
Figure 1.6. Comparison of (a) STZ decomposition curves and (b) their kinetic studies at different calcination temperatures (200~500 ℃). 37
Figure 1.7. Comparison of (a) STZ decomposition curves and (b) their kinetic studies at different TiO₂ catalyst doses (0.025~2.0 g). 39
Figure 1.8. (a) STZ decomposition curves and (b) their kinetic studies at various initial pH conditions. 40
Figure 1.9. (a) STZ decomposition curves and (b) their kinetic studies at various initial STZ concentrations. 41
Figure 2.1. SEM images of PP particle surface of (a) untreated, (b) treated with UV irradiation, (c) UV/TiO₂, (d) UV/TiO₂/H₂O₂, (e) UV/TiO₂/periodate,... 56
Figure 2.2. SEM images of PE particle surfaces (a) untreated, (b) treated with UV irradiation, (c) UV/TiO₂, (d) UV/TiO₂/H₂O₂, (e) UV/TiO₂/periodate, and... 58
Figure 2.3. SEM images of PE particle surface of (a) treated UV/TiO₂ and component graph (b) of attached particles in an image (a) 59
Figure 2.4. SEM images of PS particle surfaces (a) untreated, (b) treated with UV irradiation, (c) UV/TiO₂, (d) UV/TiO₂/H₂O₂, (e) UV/TiO₂/periodate, and... 60
Figure 2.5. (a) FTIR spectra of PP samples after 300 h of UV irradiation combined with TiO₂ and oxidants, (b) enlarged spectra for the carbonyl... 65
Figure 2.6. (a) FTIR spectra of PE samples after 300 h of UV irradiation combined with TiO₂ and oxidants, (b) enlarged spectra for the carbonyl... 69
Figure 2.7. The low-resolution XPS spectra with C:O ratio of PP samples: (a) untreated, (b) treated with UV, (c) UV/TiO₂, (d) UV/TiO₂/H₂O₂, (e)... 71
Figure 2.8. Deconvolution of high-resolution spectra for C1s of PP samples. 74
Figure 2.9. Deconvolution of high-resolution spectra for O1s of PP samples. 75
Figure 2.10. The low-resolution XPS spectra and C:O ratio of PS samples: (a) untreated, (b) treated by UV, (c) UV/TiO₂, (d) UV/TiO₂/H₂O₂, (e)... 77
Figure 2.11. Deconvolution of high-resolution for C1s of PS samples for each system. 79
Figure 2.12. Deconvolution of high-resolution spectra for O1s PS samples for each system. 80
Figure 2.13. Polypropylene photo-degradation mechanism 86
Figure 2.14. Norrish I and II pathways of ketones produced from polypropylene photolysis. 87
Figure 2.15. Polyethylene photo-degradation mechanism 90
Figure 2.16. Polystyrene photo-degradation mechanism 93