Xúc tác quang hóa ti o2 pha tạp vanadi ứng dụng xử lý nước thải

TRƯỜNG ĐẠI HỌC BÁCH KHOA HÀ NỘI LUẬN VĂN THẠC SĨ Xúc tác quang hóa TiO2 pha tạp vanadi ứng dụng xử lý nước thải NGUYỄN ĐỨC MẠNH Manh.ND202421M@sis.hust.edu.vn Ngành Hóa học Giảng viên hướng dẫn: PGS TS Nghiêm Thị Thương Viện Kỹ thuật Hóa học, ĐHBKHN TS Esteban Mejia Viện LIKAT, ĐH Rostock HÀ NỘI, 10/2022 Chữ ký GVHD Chữ ký GVHD HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY MASTER THESIS Visible light-driven photocatalysts based on V-doped TiO2 for wastewater treatment NGUYEN DUC MANH Manh.ND202421M@sis.hust.edu.vn Master of Science in Chemistry Supervior: Assoc Prof Nghiem Thi Thuong School of Chemical Engineering, HUST Dr Esteban Mejia Leibniz Institute for Catalysis, UR Hanoi, 10/2022 Signature Signature ĐỀ TÀI LUẬN VĂN Tên đề tài: Xúc tác quang hóa TiO2 pha tạp vanađi ứng dụng xử lý nước thải Giảng viên hướng dẫn Giảng viên hướng dẫn phụ PGS TS Nghiêm Thị Thương TS Esteban Mejia Acknowledgments First of all, I would like to express my deepest gratitude towards Dr Esteban Mejia, Department of Biocatalysis & Polymer Chemistry, Leibniz Institute for Catalysis, for giving me the great opportunity to work in his group and for his guidance as well as his outstanding support during my master’s research I would like to thank Dr Nguyen Van Anh, School of Chemical Engineering, Hanoi University of Science and Technology, for giving me the concept of my thesis and her helpful guidance I am also thankful to Assoc Prof Nghiem Thi Thuong, School of Chemical Engineering, Hanoi University of Science and Technology, for her all advice and her much support throughout the master’s program I am also indebted to M.Sc Paul Hünemörder, M.Sc Gustavo Alvarez and M.Sc Shuoping Ding at Leibniz Institute for Catalysis, who supported my research with a great deal of valuable discussions Special thanks go to my Vietnamese friends, namely Hung, Thuyen, Tuan, M.Sc Phong Dam, as well as the Vietnamese pioneers, namely Dr Huyen Vuong, Dr Hieu Do, Dr Binh Ngo, M.Sc Trang Pham, M.Sc Quyen Phung, M.Sc Vien Che, for their understanding and for giving me the warm atmosphere in Rostock I would like to thank the RoHan project for giving me the excellent opportunity to visit Germany for studying with fully financial support Last but not least, I am wholeheartedly grateful to my family, especially my parents, my sister, my uncle and his wife for their unconditional love, their encouragement and never-ending support Abstract Trichloroethylene (TCE) is a volatile chlorinated organic compound (VCOC) commonly used as a solvent in automotive, metal, finishing, and textile industries Wastewaters contaminated with TCE are a pollutant of serious concern in groundwaters, as it is harmful to aquatic and surface ecosystems and to the human health There are various reported methods for the degradation of TCE in aqueous media, including the “air stripping method”, where the volatilization is often incomplete, and consequently a residual amount of TCE can still be found in the treated water Moreover, gas-phase degradation of TCE produces toxic by-products such as phosgene and dichloroacetyl chloride Photocatalytic degradation of VCOCs in the aqueous phase using semiconductors such as TiO2 is well known and offers a promising alternative owing to its costeffectiveness and nontoxicity However, pure TiO2 can only absorb UV light, which accounts for 5% of the solar spectrum, thus restricting its practical application Furthermore, the rapid recombination of photogenerated electron-hole pairs kinetically impedes many desired routes to complete pollutant mineralization In this regard, vanadium ions doping has been considerably investigated to improve the optical properties of TiO2 as well as to promote separation of electron-hole pairs In this work, vanadium-doped TiO2 photocatalysts were prepared via a simple one-step hydrothermal method for photocatalytic degradation of TCE at a high concentration in aqueous phase Different characterization methods were employed to reveal the role of vanadium in the enhancement of visible light absorption as well as charge separation, which lead to an improved photoactivity of catalysts In addition, the study also provides evidence for the formation of V 2O5 on the surface of TiO2 when doping at high vanadium concentrations and its influence on the photodegradation of TCE under visible light was also discussed Master student NGUYEN DUC MANH Table of Contents LIST OF FIGURES i LIST OF TABLES iv LIST OF ABBREVIATION v CHAPTER I INTRODUCTION I.1 Water Crisis I.2 Trichloroethylene I.2.1 I.2.2 identity and Properties Disposal I.2.3 effects and Human’s health risks I.3 I.3.1 Applications and Environmental Nanostructured Titanium Dioxide Crystallographic properties I.3.2 properties I.3.3 Chemical methods Structural and Optical 12 Preparation 16 I.4 Photocatalysts based on TiO2 materials in wastewater treatment .22 I.5 Research objectives 28 CHAPTER II MATERIALS AND METHODS 29 II.1 Chemicals 29 II.2 Materials characterization 29 II.3 Materials preparation 31 II.4 Photocatalytic activity experiments 32 II.5 Recycling experiments for catalysts 33 CHAPTER III RESULTS AND DISCUSSION 34 III.1 XRD analysis 34 III.2 FT-IR and Raman spectra 36 III.3 ICP-OES analysis 38 III.4 SEM – EDX data 38 III.5 BET surface area and pore distribution 40 III.6 XPS measurements 41 III.7 Morphological properties 43 III.8 Optical properties 44 III.9 Photocatalytic performance 46 III.10 Proposed mechanism 49 CHAPTER IV CONCLUSION 53 REFERENCES 54 APPENDIX 58 LIST OF FIGURES Figure I.1 Families collecting water from water well in Africa (left) and the industrial wastewater disposal in Asia (right) (Source: UNICEF, 2020) Figure I.2 Proportion of population using safely managed drinking water services, 2017 [1] (%) Figure I.3 Applications of Trichloroethylene (all images were taken without permission from public internet sites The rights belong to the corresponding sources) Figure I.4 Illustration of air-stripping technology (Source: Federal Remediation [12] Technologies Roundtable) Figure I.5 Unit cell of TiO2 phases: (a) Anatase, (b) Rutile, and (c) Brookite; blue and [21] red spheres represent titanium and oxygen atoms, respectively Figure I.6 Crystallite structure of TiO2 phases: (a) Anatase, (b) Rutile, and (c) Brookite Figure I.7 the XRD patterns and the ball-and-stick structures of (a) anatase, (b) rutile, [28] and (c) brookite 11 [22] [34] Figure I.8 The ideal structure of TiO 2(B) 12 Figure I.9 Comparison of recombination pathways of electron-hole pairs within the [41] direct band-gap semiconductor and the indirect band-gap semiconductors 14 Figure I.10 Photo-induced reactions in the TiO2 photocatalysis versus the [42] corresponding time 16 [44] Figure I.11 Effect of the initial pH on the TiO morphology 18 Figure I.12 Different possible growth mechanisms for the formation of TiO2 [28] nanostuctures 19 [47] Figure I.13 The proposed condensation pathway for the nucleation of TiO crystals 22 Figure I.14 Photocatalytic activities of different shape-controlled TiO2 nanomaterials [50] for MO degradation and SEM images of TiO2 nanomaterials 23 Figure I.15 Mechanism of photocatalytic reactions of V-doped TiO2 under UV-Vis irradiation 25 Figure I.16 The PL spectra and catalytic activity of V-modified TiO2 samples calcined at 300 oC from [54] 26