1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY NGUYEN TUAN ANH PHOSPHORUS DOPED 1 DIMENSIONAL GRAPHITIC CARBON NITRIDE FOR PHOTOCAT[.]
THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY NGUYEN TUAN ANH PHOSPHORUS DOPED 1-DIMENSIONAL GRAPHITIC CARBON NITRIDE FOR PHOTOCATALYTIC DEGRADATION OF DICLOFENAC 10 BACHELOR THESIS 11 12 13 Study Mode : Full-time 14 Major : Environmental Science and Management 15 Faculty : Advanced Education Program Office 16 Batch : 2014 – 2018 17 18 19 20 21 Thai Nguyen, 20/08/2018 Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of Environmental Science and Management Student name Nguyen Tuan Anh Student ID DTN1453110003 Thesis Title Phosphorus doped 1-dimensional graphitic carbon nitride for photocalytic degradation of diclofenac Supervisor Prof Dr Ruey-an Doong- National Chiao Tung University, Taiwan Dr Duong Van Thao – Thai Nguyen University of Agriculture and Forestry Supervisor’s signature Abstract: In the past ten years, graphitic carbon nitride (g-C3N4) become an interesting metal-free material due to earth-abundance, nontoxicity, visible light respond, chemical and thermal stability as well as facile preparation, which can be used for a variety of environmental applications Nevertheless, some drawbacks of g-C3N4, such as low surface area, low charge separation efficiency and deficient visible light absorbance, limit its application Hence, the aim of this study is to fabricate1dimentional (1-D) structure along with the introduction of phosphorus dopant to overcome these short coming of g-C3N4 The results reveal that the phosphorus dopant and morphology design of tubular structure can enhance the photocatalytic abilities of g-C3N4 The results also showed that tubular g-C3N4 with 1.5 wt% of phosphorous dopant exhibit the highest photocatalytic performance toward Diclofenac (DCF) degradation under visible light irradiation Keywords 1-D structure, phosphorus doped g-C3N4, photocatalytic degradation, Diclofenac Number of pages 32 Date of Submission 25th September, 2018 i ACKNOWLEAGEMENT With all my heart, I would like to express my deepest appreciation to the cooperation between Thai Nguyen University of Agriculture and Forestry and University System of Taiwan, especially National Chiao Tung University for providing me an amazing opportunity to complete this thesis Foremost, I would like to say my sincere gratitude and deep regards to my Taiwanese supervisor: Prof Dr Ruey-an Doong whose guided and gave me suggestions wholeheartedly when I implemented this research Besides my Taiwanese supervisor, I would like to say thankful my second supervisor: Dr Duong Van Thao for his supervision, encouragement, advice, and guidance in writing this thesis My special thanks go to Luong Nguyen who offered me a warm welcome and provided the information and data necessary for my implementation process and helped me finish this thesis Besides, she was not so patient with my knowledge gaps only, but she also was very enthusiastic for providing me suggestions and methods to successful complete my experiments Furthermore, it was really fortunate for me to worked in Prof Ruey-an Doong’s lab, I want to deeply thanks to all the members in Professor Doong’s laboratory special Binh, David, Alice and Sara who helped me a lot during the time that I did my research in Taiwan My sincere thanks also go to my classmates – AEP K46 especially: Nam, Nguyen for supporting me when I stayed in Taiwan Last but not the least, I would like to thank all of my family members who always encourage and back me up unceasingly Hsinchu – Taiwan, June 2018 Nguyen Tuan Anh ii LIST OF CONTENT LIST OF FIGURE v LIST OF TABLE vi LIST OF ABBREVIATIONS vii PART INTRODUCTION 1.1 Research rationale 1.2 Research’s objectives 1.3 Research questions 1.4 Limitations PART LITERATURE REVIEW 2.1.Diclofenac in the environment 2.2 g-C3N4-based photocatalysts for photocatalysis 2.1.1 Principle of photocatalysis 2.2.2 Metal-free g-C3N4 photocatalyst 2.2.3 Non-metal doped-g-C3N4 10 PART METHOD 12 3.1 Chemicals 12 3.2 Experimental section 12 3.2.1 Synthesis tubular structures of Phosphorous-doped g-C3N4 (PCN) 12 3.2.2 Photocatalytic activities of P-C3N4 toward DCF 13 3.3 Analytical methods 14 3.3.1 X-ray Diffraction (XRD) 14 3.3.2 Brunauer-Emmett-Teller (BET) 15 3.3.3 Scanning electron microscope (SEM) 15 3.3.4 UV-visible spectroscopy (UV-Vis) and band gap 16 3.3.5 Fluorescence (FL) 16 PART RESULTS 17 iii 4.1 Characterizations of PCN 17 4.1.1 XRD spectra of pure g-C3N4 and phosphorus doped g-C3N4 17 4.1.2 Morphology of g-C3N4 and PCN 18 4.1.3 BET surface area analysis 18 4.1.4 UV-Vis analysis 20 4.2 Application of P-C3N4 for photocatalytic degradation of Diclofenac (DCF) Photocatalytic degradation of DFC under visible light irradiation 23 PART DISCUSSION AND CONCLUSION 25 5.1 Discussion 25 5.2 Conclusion 25 REFFERENCES 27 iv LIST OF FIGURE Figure 2.1 Sources and transport pathways of antibiotics in the environment Figure 2.2: Schematic representation of semiconductor photocatalytic mechanism of the semiconductor, the valence band electrons are agitated and move to the conduction band of the semiconductor Figure 2.2.2 Diagrammatic illustration of polymerization method for synthesis gC3N4 by condensation of melamine, urea, thiourea, cyanamide, dicyandiamide Figure 2.3 (a) Triazine and (b) tri-s-triazine/heptazine unit structures of g- C3N4 10 Figure 3.1 Schematic diagram of the synthesis boron, phosphorus co-doped 1-D C3N4 13 Figure 4.1 XRD patterns of pure g-C3N4 and PCN-1.5 17 Figure 4.3 SEM images of g-C3N4 and PCN samples 18 Figure 4.4 BET surface area and pore-size distribution analysis of pure g-C3N4 and PCN-1.5 19 Figure 4.5 UV-Vis diffuse reflectance spectroscopy (DRS) of pure g-C3N4 and PCNx samples 20 Figure 4.6 Corresponding band gaps of undoped-g-C3N4 and PCN-x 21 Figure 4.7 Photoluminescence emission spectra of pure g-C3N4 and PCN with different phosphorous doping obtain at room temperature 22 Figure 4.8 Photocatalytic degradation of DFC solution under visible light (catalyst dose: g/L, initial DFCs concentration: 10 mg/L) 24 v LIST OF TABLE Table 2.1 The chemical structure and physicochemical properties of diclofenac Table 3.1 The characteristics of analytical instruments used in this study 14 Table 4.1 Calculated band gap (eV) of pure g-C3N4 and PCN-x samples 22 vi LIST OF ABBREVIATIONS BET Brunauer-Emmett-Teller DCF Diclofenac FL Fluorescence g-C3N4 Graphitic carbon nitride H3PO4 Phosphoric acid NSAID Anon-steroidal anti-inflammatory drug PCN Phosphorous-doped g-C3N4 PL Photoluminescence SEM Scanning Electron Microscopy TEM Transmission Electron Microscopy UV Ultraviolet UV- vis Ultravioliet- visible and visible spectrophotometer vii PART INTRODUCTION 1.1 Research rationale Antibiotic contaminants leaching from industrial and/or domestic effluents may be harmful directly or indirectly to human health and balanced ecology, which results in reducing the quality of the aqueous environment Therefore, these pollutants should eliminate certain levels that not pose any damage to the environment before discharging Chemical, physical and biological methods have been widely used for the removal of antibiotics from effluents Among the available chemical methods, advanced oxidation processes (AOPs) have been explored as an alternative method forremoval a huge number of antimicrobial resistance as conventional treatment methods are inadequate for treatment of trace contaminants Graphitic carbon nitride (g-C3N4) is considered as a non-metal photocatalyst which has received numerous studies due to its unique properties and multifunctional applications in photo degradation of organic pollutants, photocatalytic water splitting, CO2 photoreduction, sensing, and energy conversion (Ma, et al, 2014) The promising properties enable g-C3N4 to obtain bright future in the photocatalytic application, disadvantages of g-C3N4, such as low surface area, high recombination rate and low electronic conductivity, result in low photocatalytic efficiency and limits its practical applications Therefore, more future researches and development to obtain efficient g- C3N4 based photocatalyst should be seriously consider Recently, various efforts have been studied to enhance the photocatalytic effectiveness of gC3N4 by modifying its band gap, morphology and separation of photogenerated electrons and holes, which including numerous modification routes, such as nonmetal and metal doping, coupling with semiconductors, and control of the morphology To date, g-C3N4 doping with non-metal elements are consider as cost1 effective, environmental-friendly and facile-synthesized strategies Along with nonmetal doping, the design of one-dimensional structures, such as nanorods, nano/microfiber and nano/micro tubes, are attractive candidates and seen as simple ways to improve photocatalytic activity of g-C3N4 In this study, the fabrication of gC3N4 with tubular structure design together with non-metal element doping for improvement of Diclofenac photocatalytic degradation were investigates 1.2 Research’s objectives The primary purpose of this study is to enhance the photocatalytic performance of graphitic carbon nitride (g-C3N4) by the introduction of non-metal dopant and design of one-dimensional structure for photocatalytic degradation of antibiotics under visible-light condition To accomplish this objective, g-C3N4 is taken as the base material with the various amount of phosphorous doping Melamine was used as aprecursor of g-C3N4, while phosphoric acid (H3PO4) was selected as the phosphorous source for phosphorous doping The surface morphologies of phosphorous doped-C3N4 structure were identified by scanning electron microscope (SEM) The crystalline structures were characterized by X-ray powder diffraction (XRD) The specific surface area and pore size distribution were calculated by Brunauer-Emmett-Teller (BET) method using a BET N2 adsorption analyzer The optical properties and band gaps were measured by Fluorescence and UV-Visible spectrometer 1.3 Research questions - What is the characteristics g-C3N4 of nanocomposites? - How to enhance the photocatalytic performance of graphitic carbon nitride (gC3N4)? 1.4 Limitations Since the time for an internship was too short, this research project could not perform any other experiments