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국회도서관 홈으로 정보검색 소장정보 검색
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Title Page

Contents

Abbreviations 12

Abstract 13

Ⅰ. INTRODUCTION 15

1. Microplastics (MPs) 15

1.1. Definition, classifications, and types of MPs 15

1.2. Environmental and human health risk exposed MPs 19

2. Overview of MPs removal technologies 23

2.1. Introduction of MPs removal technologies 23

2.2. Biological degradation 25

2.3. Filtration using membranes 27

2.4. Electro/chemical coagulation 29

3. Bioinspired coagulation using coordination bonds 34

3.1. Coordination bonds between metal and phenolic molecules 34

3.2. Coordination bonds-based complexation 36

4. Risk assessment of MPs 39

4.1. In vitro studies for risk assessments 39

4.2. In vivo studies for risk assessments 41

5. The objective of this thesis 47

Ⅱ. EXPERIMENTAL SECTION 50

1. Two steps-surface modification of MPs 50

1.1. Formation of coordination bonds-based complex 50

1.2. Surface modification of polystyrene (PS) or polyethylene (PE) beads 50

1.3. Coagulation of PS/PE beads and filtration of coagulated beads 51

1.4. In vitro studies for risk assessments 52

1.5. In vivo studies for risk assessments 55

2. Single step-surface modification of MPs 62

2.1. TA-CS conjugates 62

2.2. Characterizations of TA-CS 62

2.3. Surface modification of microbeads (MBs) using TA-CS 63

2.4. Coagulation of beads and filtration of coagulated beads 63

2.5. In vitro studies for risk assessments 64

Ⅲ. RESULTS AND DISCUSSION 68

1. Two steps-surface modification of MPs 68

1.1. Identification of coordination bonds in coordination complex 68

1.2. Characterizations of surface modification 70

1.3. MPs Removal efficiency 80

1.4. Risk assessments of PS beads by concentration in vitro 88

1.5. Biodistribution, toxicity, ROS, SOD and inflammatory responses in vivo 90

2. Single step-surface modification of MPs 102

2.1. Characterizations of TA-CS 102

2.2. Surface modification of beads using TA-CS 105

2.3. Removal efficiency of PS/PE/Poly(methyl methacrylate) (PMMA) beads 108

2.4. Risk assessments of PS/PE/PMMA beads in vitro 112

Ⅳ. CONCLUSION 114

Ⅴ. REFERENCES 116

요약 133

Curriculum Vitae 135

List of Tables

Table. 1. Toxic substances bound to MPs that form in the environment. Substances such as halogens, toxic substances and organic pollutants are easily detected by binding to MPs that... 20

Table. 2. A summary of MPs purification technologies of biological degradation, filtration, and coagulation methods. 33

Table. 3. Pathological, toxicological, and behavioral changes to MPs treatment in rats and mice. 44

List of Figures

Figure 1. Classification of plastics by size. Plastics with a size of 5 mm or less are classified as MPs. 16

Figure 2. Pathways by MPs produced in the environment. Primary MPs produced by industrial production, and secondary MPs produced by degradation of plastics. 17

Figure 3. Types of MPs in the ocean through 39 studies. (a) PS, PP, PE, and PP&A were representative types of MPs (b) Distribution in the ocean of MPs produced by polymer types. 18

Figure 4. Human exposure routes to MPs. MPs are exposed to humans through a variety of routes, including air, food, and bottled water. 21

Figure 5. Annual intake of MPs from exposure routes such as air, food, and bottled water. Exposure to large amounts of MPs person per year. 22

Figure 6. Overview of microplastics separation methods in simple and complex matrices. 24

Figure 7. The growth curve of (a) Bacillus cereus and (b) Bacillus Gottheilii for the MPs biodegradation. 26

Figure 8. Schematic of a pilot scale anaerobic membrane bioreactor system with three sampling zones. 1: untreated wastewater, 2: preliminary wastewater, 3: final wastewater. 28

Figure 9. Schematic diagram of the removal of MPs using the electrocoagulation method used in the investigation. 31

Figure 10. Schematic diagram of coagulation and ultrafiltration processes for MPs removal [41]. MPs: microplastics, PAM: polyacrylamide, UF: ultrafiltration. 32

Figure 11. Adhesion found in mussels. A catechol group called 3,4-dihydroxyphenylalanine (Dopa) in mussels is coordinated by a metal ion. 35

Figure 12. Schematic diagram of pH-responsive drug delivery system using pH-dependent coordination complex. 37

Figure 13. Self-healing type applications using the properties of weak or strong coordination bonds. 38

Figure 14. The effect of HepG2 cells on cell viability and malondialdehyde (MDA) content on various concentrations of PS, PS-COOH and PS-NH2. (a) Cytotoxicity to MPs in HepG2... 40

Figure 15. Routes of exposure in humans and various routes of toxicity of MPs. 42

Figure 16. Effect of intestinal mucus secretion by PS MPs exposure. Normalizing mucus secretion used the ratio of mucus secretion area to the total colon area after AB-PAS (alcian... 46

Figure 17. Schematic diagram of removal of microplastics via phenolic compounds-mediated coagulation and risk assessment. (a) Removal of microbeads via a two steps of... 49

Figure 18. A coordination complex formed by mixing an aqueous TA solution and an aqueous Fe³⁺ solution. (a) After mixing, the color changed to black, and the coordination... 69

Figure 19. Scanning electron microscopy images of (a) 90 μm -sized PS beads (b) PS beads modified with CS (PS beads/chitosan) (c) PS beads additionally modified with TA (PS... 71

Figure 20. Scanning electron microscopy images of (a) 0.5 μm -sized PS beads (b) PS beads modified with CS (PS beads/chitosan) (c) PS beads additionally modified with TA (PS... 73

Figure 21. Scanning electron microscopy images, atomic percentage, zeta potential of (a) 106-125 μm -sized PE beads (b) 45-53 μm -sized PE beads. 75

Figure 22. Size and zeta potential according to the surface change of PS beads (0.5 μm). (a) CS 24 h and GA 2 h treatment (b) CS 6 h and TA 2 h treatment (c) CS 6 h and GA 2 h treatment. 77

Figure 23. Size and zeta potential as a function of surface change of PS beads (0.5 μm) (a) PDADMAC 24 h and TA 2 h treatment (b) PDADMAC 24 h and GA 2 h treatment (c)... 79

Figure 24. (a) Photograph by treatment of fluorescent PS beads (0.5 μm). #1: Untreated fluorescent beads. #2: 5 min after adding Fe³⁺ to the modified phenolic surface. #3: After... 81

Figure 25. Removal efficiency of fluorescent PS beads (0.5 μm) under various conditions. (a) reaction (coagulation) time (b) concentration of PS beads (c) volume of sample (d) actual... 83

Figure 26. Removal efficiency of fluorescent PS beads according to CS treatment time and GA treatment. Chitosanx-TAy or GAy: x and y are the treatment times (hours) for PS beads. 85

Figure 27. Removal efficiency of fluorescent PS beads according to PDADMAC treatment time and GA treatment. PDADMACx-TAy or GAy: x and y are the treatment times (hours)... 87

Figure 28. Using IEC18, in vitro tests of (a) cell viability, (b) oxidative stress (reactive oxygen species) levels, (c) inflammation, and (d) cytokines of treatment with PS beads (0.5... 89

Figure 29. Total amount of PS beads (0.5 μm) accumulated in each organ: The values of biodistribution are based on mass of PS beads present in each organ, calculated by... 91

Figure 30. Effect of PS NP on the biochemical markers and histopathological structure of the three organs. The group-dependent expression levels of (a) aspartate aminotransferase... 92

Figure 31. Effect of PS beads on inflammatory mediators and cytokines in liver tissue. (a) Expression levels of iNOS and COX-2 protein in liver tissue of PS beads treated groups. (b-... 94

Figure 32. Effect of PS beads on oxidative stress mediators in liver tissue. (a-b) ROS concentration and SOD activity in liver tissue of PS beads treated groups. (c) Expression... 95

Figure 33. Effect of PS beads on inflammatory mediators and cytokines in kidney tissue. (a) Expression levels of iNOS and COX-2 protein in kidney tissue of NP treated groups. (b-e)... 97

Figure 34. Effect of PS beads on oxidative stress mediators in kidney tissue. (a-b) ROS concentration and SOD activity in kidney tissue of NP treated groups. (c) Expression levels... 98

Figure 35. Effect of PS beads on inflammatory mediators and cytokines in intestinal tissue. (a) Expression levels of iNOS and COX-2 protein in intestinal tissue of PS beads treated... 100

Figure 36. Effect of PS beads on oxidative stress mediators in intestinal tissue. (a-b) ROS concentration and SOD activity in intestinal tissue of PS beads treated groups. (c) Expression... 101

Figure 37. TA-CS characterizations by TA concentration. (a) Structure of TA-CS (b) TA-CS 1H NMR according to TA concentration (c) TA-CS phenolic content according to TA... 104

Figure 38. Scanning electron microscopy images of (a) 90 μm -sized PS beads (b) PS beads modified with TA-CS (PS beads-TA-CS) The yellow square area of the beads surface was... 106

Figure 39. Zeta potential of (a) 106-125 μm -sized PE beads (b) 75-90 μm -sized PMMA beads following modifications of PS beads. 107

Figure 40. (a) Photograph by treatment of PS beads (90 μm). #1: Untreated beads. #2: 5 min after adding Fe³⁺ to the modified phenolic surface. (b) Untreated beads #1, (c and d)... 109

Figure 41. Removal efficiency of PS beads (90 μm), PE beads (105-125 μm), and PMMA beads (75-90 μm). CS and TA-CS were the removal efficiencies obtained from PS beads (90... 111

Figure 42. Using IEC18, in vitro tests of (a) cell viability, (b) oxidative stress (reactive oxygen species) levels, (c) inflammation, and (d) cytokines of treatment with PS beads (90... 113

초록보기

미세플라스틱 (MPs)은 전 세계적으로 공기, 바다 및 토양에 분포되어 있다. 환경에서 MPs가 환경과 잠재적으로 인간의 건강에 미치는 유해한 영향에 대한 인식이 증가하고 있다. 일반적으로 MPs 제거를 위해 여과, 생물학적 분해 및 응고 (MPs를 더 큰 응고물로 결합하는 과정)의 세 가지 방법이 사용된다. 여과법의 제거 효율은 필터의 기공 크기나 응고된 MPs의 크기에 따라 다르다. 생물학적 분해는 친환경적이지만 MPs 분해가 4주 동안 5%만의 제거되는 단점이 있다. Fe- 또는 Al-염은 금속 이온과 MPs 사이의 정전기 상호 작용을 갖는 응집제로 사용되지만 응집제 농도가 높은 경우에도 제거 효율이 40% 미만이다.

본 논문에서는 단시간에 MPs 크기에 독립적인 제거효율 향상을 위해 금속-페놀 배위결합을 응집법으로 새롭게 적용했다. 식물유래 페놀분자를 이용하여 금속-페놀에서 형성되는 강한 결합인 배위결합을 응고에 사용했다. 탄닌산 (TA)과 갈산 (GA)은 페놀 분자로 MBs의 표면을 페놀성으로 변경했다. 페놀성 표면을 가진 MBs는 Fe3+와의 계면에서 배위 결합을 형성했다. 변형된 0.5 µm 크기의 폴리스티렌 (PS) 비드의 제거 효율은 다양한 조건에서 5분 이내에 95% 이상이었다. 이는 기존 응고 방법의 2배다. 또한, 응고된 MBs는 5분 내 소량의 응고제와 배위결합에 의해 형성되었다. MPs는 대부분의 동물 장에 축적되기 때문에 MBs를 마우스의 장 IEC18 세포에서 위험 평가와 마우스의 간, 신장 및 장의 위험 평가 및 생체 분포를 평가하는 데 사용했다. 세포 실험에서 산화 스트레스와 염증성 사이토카인 수치는 PS 비드의 농도에 의해 증가했다. 그러나 응고 기반 정제수는 PS 비드가 없는 물과 비교하여 유사한 수준을 나타냈다. 동물실험에서 2주 동안 PS 비드를 경구투여로 노출된 ICR 마우스를 분석했다. PS 비드는 간, 신장, 장에서 검출되었으나 PS 비드의 축적은 장에서 가장 높았다. 활성산소종 (ROS), 슈퍼옥사이드 디스뮤타제 (SOD), 염증 반응 및 사이토카인 수준이 PS 비드에 노출된 간, 신장 및 장에서 증가했습니다. 그러나, 비히클 처리군과 비교하여 응고 기반 정제수에서 유사한 염증 수준을 나타냈다.

MPs의 표면 개질에는 키토산과 탄닌산이 결합된 TA-CS를 이용해 단일 단계로 처리 시간을 단축했다. TA-CS를 사용하여 표면 개질된 90-125 µm 크기의 PS/폴리에틸렌 (PE)/폴리(메틸메타크릴레이트) (PMMA) 비드에서 제거 효율은 80% 이상이었다. 동일한 농도의 PS/PE/PMMA 비드는 IEC 18 세포에서 다른 수준의 산화 스트레스와 염증성 사이토카인을 나타냈지만 응고 기반 정제수는 더 낮은 수준이었다.

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