THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY TRAN THI LE VAN TOPIC TITLE: FACILE PHOTOCHEMICAL SYNTHESIS OF GOLD NANOPARTICLES- GRAPHITIC CARBON NITRIDE (Au@g-C3N4) FOR 4-NITROPHENOL REDUCTION BACHELOR THESIS Study Mode : Full-Time Major : Environmental Science and Management Faculty : International Programs Office Batch : 2013 – 2017 Thai Nguyen, 20/08/2017 n Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of Environmental Science and Management Student name Tran Thi Le Van Student ID DTN1353110296 Thesis Title Facile photochemical synthesis of gold nanoparticles- graphitic carbon nitride (Au@g-C3N4) for 4-nitrophenol reduction. Ruey- an Doong- National Chiao Tung University, Taiwan. Tran Quoc Hung - Thai Nguyen University of Agriculture and Forestry, Vietnam. Abstract: In this study, we have demonstrated that Au/g-C3N4 nanocomposite with different Au contents has been fabricated via facile one-step synthesis as photodeposition of Au ions onto g-C3N4 nanosheets.
Au NPs with average diameter of 5-15 nm were deposited onto the surface of g-C3N4. The as-prepared Au/g-C3N4 nanocomposites exhibit excellent catalytic activity toward 4-nitrophenol reduction and is highly dependent on reactant concentration, metal loading and pH. The apparent rate constant for 4-NP reduction by 2 wt% Au/g-C3N4 is 0. The 2 wt% loading amount of Au NPs onto the g-C3N4 performs the highest conversion.
and can be reused for 10 consecutive catalytic cycles without a considerable loss in catalytic activity. The possible mechanism of binary catalyst for enhanced conversion efficiency of 4-nitrophenol was also investigated based on the experimental results. Our results clearly demonstrate that the combination of low mass of Au NPs and g-C3N4 is a reliable green chemistry with great potential applications for catalytic transformation in the field of environmental remediation. n Keywords Gold- carbon nitride, nanocomposite, 4-nitrophenol, NaBH4 , hole scavenger, reduction.
Number of pages 49 Date of submission 20th September, 2017 Supervisor’s signature n 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. 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: Assoc.
Tran Quoc Hung for his supervision, encouragement, advice, and guidance in writing this thesis. My special thanks go to Mr. Nguyen Thanh Binh (Ph.D) who offered me a warmly welcome, assisted me in the synthesis of nanoparticles and various other techniques. Besides, he was not so patient with my knowledge gaps only, but he 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: Mrs. Nguyen Thi Ngoc Anh, Ms. Khuat Thi Thanh Huyen, Ms.
Duong Thi Ngoc Anh who helped me a lot during the time that I did my research in Taiwan. My sincere thanks also go to my classmates – k45 AEP especially: Trung, Pim, Manh, Lam, Noy for supporting me when I stayed in Taiwan. n 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, May 2017 Tran Thi Le Van n TABLE OF CONTENT PART I.
Definition and sources of 4-nitrophenol:. Characteristics of 4-nitrophenol:. 4-nitrophenol pollution in the world and Vietnam. Effecting of 4-nitrophenol to environment and human’s health.
The characteristics and health effects of Sodium Borohydride (NaBH4). Method for treament 4-nitrophenol in aqueous solutions .2 Overview of Graphitic carbon nitride: (C3N4).3 Overview of nanocomposite. MATERIALS AND METHODS .1 The synthesis of C3N4 .2 The synthesis of Au@g-C3N4 .4 The methods for determining the characteristics of material .2 Scanning Electron Microscopy ( SEM) .3 Transmission Electron Microscopy ( TEM).4 High-resolution Transmission Electron Microscopy (HRTEM) .5 UV-vis spectrophotometer ( UV- vis). X-ray diffraction of g-C3N4 and Au@g-C3N4 nanocomposite .2 Morphology of g-C3N4 and Au@g-C3N4 nanocomposite .4 Application of Au@g-C3N4 for reduction of 4-nitrophenol .5 Effect of the concentration of NaBH4 on the catalytic activity of Au/g-C3N4.
DISCUSSION AND CONCLUSION. 37 n LIST OF FIGURES Figure 2.1: the crystal structure of the three forms of gold nanoparticle .2 the crystal structure of graphitic carbon nitride, g-C3N4.1: Some instruments used for this study.1 Schematic of the synthesis g-C3N4.2 Schematic of the synthesis Au@g-C3N4 .1: Schematics of X-ray diffractometer technique used for crystal structure analysis.2: Schematic diagram of SEM .3: Schematic diagram of TEM .4: The effect of pH on Zeta potential .5 Schematic of UV – vis .1: XRD patterns of g-C3N4 and Au@g-C3N4 nanocomposite .2 A : SEM images of the synthesis a) g-C3N4 and b) Au@ g-C3N4 composites .2 B : TEM images of the synthesis g-C3N4 and Au@ g-C3N4 (a,b) composites, c) HRTEM image of the prepared Au@g-C3N4.3 : The effect of pH to zeta potential of g-C3N4 and Au@g-C3N4 .4 : The reduction 4-nitrophenol by Au@g-C3N4 nanocomposite at pH=4 in aqueous solution at room temperature .5 : (a) Effect of the NaBH4 concentration on the reduction of 4-NP by Au/g-C3N4 nanocomposite and (b) k values for 4-NP reduction as a function of NaBH4 concentration.1: Proposed mechanism for 4-NP reduction by NaBH4 in the presence of Au/g-C3N4. 34 n LIST OF TABLES Table 2.1: Physical and Chemical Properties of 4- nitrophenol .1: Sources of chemical materials. 15 n LIST OF ABBREVIATIONS g-C3N4 Graphitic carbon nitride nanocomposite Au@g-C3N4 Gold- Carbon nitride nanocomposite C6H5NO3 4-nitrophenol NaBH4 Sodium borohydride XRD X-Ray Diffraction SEM Scanning Electron Microscopy TEM Transmission Electron Microscopy ZP Zeta Potential UV- vis Ultravioliet- visible and visible spectrophotometer n PART I.1 Research rationale: Economic and social development have produced many benefits – raising standards of living and improving quality of life across the world – it has also resulted in the depletion of natural resources, the degradation of ecosystems and environmental issues.
Environmental pollution is a controversial issue not only in Vietnam but also in the world. With about 70% of the earth’s cover being water, it undeniably becomes one of our greatest resources. Furthermore, roughly 70% of an adult’s body made up of water. So, water is very important for human.
Water pollution is an appalling issue, powerful enough to lead the world on a path of destruction. Water is an easy solvent, enabling most pollutants to dissolve in it easily and contaminate it. The most basic effect of water pollution is directly suffered by the organisms and vegetation that survive in water, including amphibians. On a human level, several people die each day due to consumption of polluted water contained 4-nitrophenol.
4-nitrophenol is known by using to manufacture insecticides, drugs, fungicides and dyes so they can accumulate in water environment, posing great threat to both human health and ecological environment. (Department of Health and Human Services, Atlanta, GA.) Besides, 4-nitrophenols can be formed in the air as a result of the breakdown of many other manufactured chemicals, or they are a breakdown product of other pesticides also. From that, they may severely irritate skin and eyes and poisonous by ingestion and moderately toxic by skin contact, moreover, inhalation or ingestion of 4- 1 n nitrophenol in humans causes headaches, drowsiness, nausea, and cyanosis (Agency for Toxic Substances and Disease Registry, U. In the fields of science and technology, gold nanoparticles (Au NPs) have been studied by the important role in some of catalytic processes including low-temperature CO oxidation, reductive catalysis of chlorinated or nitrogenated hydrocarbons and organic synthesis (American Chemical Society, J.
Due to the high cost so the top priorities for practical applications are the increasing of the catalytic efficiency and the reduction of the used amounts. In chemistry filed, graphitic carbon nitride (g-C3N4) is known by one of carbon nitride, because of the special semiconductor properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene. Coupling of Au NPs with g-C3N4, the Au@g- C3N4 nanocomposites can improve the optical adsorption ability as well as promote photogenerated electron−hole pairs separation and the activation of benzene. In the field of environmental protection, the research on the reduction efficiency of Au@g-C3N4 nanocomposites up to 4-nitrophenol showed that Au@g- C3N4 is a potential nanomaterial for the reduction of 4-nitrophenol in aqueous solution.
In consideration of above mentioned facets with the aim of exploiting the potential applications of Au NPs in water treatment, especially during the removal of 4- nitrophenol from the aqueous solution. I have chosen research direction of Au@g- C3N4 nanocomposites for reduction of 4-nitrophenol in the water solution and I propose my research “Facile photochemical synthesis of gold nanoparticles- graphitic carbon nitride (Au@g-C3N4) for 4-nitrophenol reduction”. Research’s objectives The objective of this study was to synthesize material and evaluate the reduction capacity for 4-nitrophenol in aqueous solution by Au@g-C3N4 nanocomposite. Research questions What is the characteristics Au@g-C3N4 of nanocomposites? How about the reduction capacity 4-nitrophenol of nanocomposites in aqueous solution? 1.
Limitations Because the time for an internship was too short, this research project could not perform any other experiments. Definition and sources of 4-nitrophenol: Table 2.1: Physical and Chemical Properties of 4- nitrophenol Chemical Name 4-Nitrophenol Phenol Common Name Structural Formula Chemical Formula C6H5NO3 100-02-7 CAS Registry Number Molar Mass 139.11 g·mol−1 Specific Gravity 1.001 mm Hg at 25 °C Vapor Pressure 7.5 ×10-6 cm3/mol Magnetic 4 n susceptibility (χ) 2. Characteristics of 4-nitrophenol: In recently, 4-nitrophenol is known by using to manufacture insecticides, drugs, fungicides and dyes so they can accumulate in water environment, posing great threat to both human health and ecological environment. In Hazardous Substances Data Bank (HSDB,1991), 4-nitrophenol is used as a chemical intermediate in the production of methyl and ethyl parathion, N-acetyl-p aminophenol dyestuffs, and leather preservatives.
Based on its vapor pressure, 4-nitrophenol is expected to exist in the gas phase in the atmosphere (as has been observed by Herterich and Hermann, 1990). So that, probable routes of human exposure to 4-nitrophenol are inhalation, ingestion, and dermal contact. EPA(1994), inhalation or ingestion of 4-nitrophenol may cause headache, drowsiness, nausea, and cyanosis. It is relatively harmful to humans when they contact with the eyes may cause irritation.
Respiratory effects, an increase in methemoglobin, effects on the liver, and corneal opacity were reported in studies of acute exposure to 4-nitrophenol in rats. 4-NP can create adverse effects on environmental and human health due to their toxicity. According to WHO, 4-nitrophenol can irritate the eyes, skin, and respiratory tract. It may also cause inflammation of those parts.
It has a delayed interaction with blood and forms methaemoglobin which is responsible for methemoglobinemia, potentially causing cyanosis, confusion, and unconsciousness. When ingested, it causes abdominal pain and vomiting. Prolonged contact with skin may cause allergic response. 4-nitrophenol pollution in the world and Vietnam.
5 n Nowadays, the environment of the world in general and of Vietnam in particular are facing with a plenty of challenges. With Vietnam- a developing country, pollution becomes increasingly prevalent in daily life. In some areas, it has a fairly negative impact on our health. Among all the pollutions, 4-nitrophenol is an important part which should be interested in.
Effecting of 4-nitrophenol to environment and human’s health. It is clearly that how a chemical affects your health depends on how much you are exposed to and for how long. As the level and length of your exposure increase, the effects are likely to become more severe. In the experiment of Agency for Toxic Substances and Disease Registry (ATSDR,1992), rats that breathed dusts of 4- nitrophenol for 2 weeks developed a blood disorder which reduces the ability of the blood to carry oxygen to tissues and organs.
However, these abnormalities disappeared a few days after exposure stopped.