THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY DUONG THI NGOC ANH TITANIUM DIOXIDE DOPING ZINC FERRITE WITH ENHANCED ULTRAVIOLET AND VISIBLE LIGHT PHOTOACTIVITY FOR METHYL ORANGE DEGRADATION BACHELOR THESIS Study Mode : Full-time Major : Environmental Science and Management Faculty : International Training and Development Center Batch : 2011-2015 Thai Nguyen, September 2015 n DOCUMENTATION PAGE WITH ABSTRACT Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of environmental Science and Management Student name Duong Thi Ngoc Anh Student ID DTN1153180128 Titanium dioxide doping zinc ferrite with enhanced Thesis Title ultraviolet and visible light photoactivity for methyl orange degradation 1, Prof. Ruey-an Doong, National Tsing -Hua University, Taiwan. Nguyen Thanh Hai, Thai Nguyen University of Agriculture and Forestry, Vietnam. Abstract: In this report, zinc ferrite (ZnFe2O4) and Titanium dioxide doping zinc ferrite nanoparticles (TiO2@ZnFe2O4) were prepared by hydrothermal method.
Ultraviolet – visible (UV-Vis) spectroscopy results show that absorption edge of TiO2@ZnFe2O4 has moved to the visible spectrum range in comparison with the undoped TiO2 and Zinc ferrite doped Titanium dioxide narrows band gap of TiO2. X-ray diffraction (XRD) result point out that zinc ferrite doping titanium dioxide promotes the phase transformation of Titanium dioxide from anatase to rutile and Transmission Electron Microscopy (TEM) result indicated that when TiO2 was doped with ZnFe2O4, it is particle size will decrease with average particle size in the range of 25-30 nm. The photocatalytic experimental results indicated that zinc ferrite doped titanium dioxide powders can effectively photodegrade methyl orange under visible light irradiation and ultraviolet irradiation. The result also indicated ii n that ZnFe2O4 doping TiO2 will enhance the photocatalytic activity of TiO2.
Keywords ZnFe2O4, TiO2@ZnFe2O4, hydrothermal, photocatalytic, methyl orange. Number of papers 40 Date of submission September 30th, 2015 Supervisor’s signature iii n ACKNOWLEDGEMENT Fortunately, I have a precious internship opportunity to learning and professional development in Department of Biomedical Engineering and Environmental Sciences in National Tsing Hua University (NTHU), Taiwan. First of all, I want to thanks my supervisors Prof. Ruey-An Doong and Dr.
Nguyen Thanh Hai, who took time out to hear, guide, support and encourage me on the correct path and allowing me to carry out my study to have successful results. Especially, their priceless advices are not a small contribution in orienting my careers and future. Moreover, I am grateful to Nguyen Thanh Binh (Ph.D) about the help dedicated of his during my studies and research in this laboratory. He was hearted guidance, given the comments and the orientation in my experiment steps as well as the process of writing my report.
I would like to thank Amber, Amy, Judy and Ruby for their guidance to use a variety of important machinery serving my experiment, Rama and Duncan for their help in perform analysis of TEM and XRD samples. I would also like to thank all FATECOL members, Biomedical Engineering and Environmental Sciences, National Tsing-Hua University, Taiwan, they going on supports and suggestions. Last but not least, thanks to my parents and good friends who always encourage me and offer support and love. Sincerely, Duong Thi Ngoc Anh iii n TABLE OF CONTENTS LIST OF FIGURES.
1 LIST OF TABLES. 3 LIST OF ABBREVATIONS. Overview of Titanium dioxide. Titanium oxidation structures and properties.
The photocatalytic activity of TiO2. Increasing the photoactivity of pure TiO2. Overview of Zinc ferrite. Properties of Zinc Ferrite.
Overview of research and application of nanomaterial. Some methods synthesized ZnFe2O4 and TiO2@ZnFe2O4. Sol-gel method. Co-precipitation methods.
15 iv n PART III. Synthesis of Zinc Ferrite nanoparticles. Synthesis zinc ferrite doped titanium dioxide P25. Photodegradation of methyl orange by TiO2@ZnFe2O4 nanocomposite.
UV-Vis spectra study. Morphology of TiO2@ ZnFe2O4. Degradation of methyl orange. Degradation of methyl orange under UV light irradiation.
Degradation of methyl orange under visible light irradiation. DISCUSSION AND CONCLUSION. 37 v n LIST OF FIGURES Figure 1. Structure of methyl orange dye.
Crystal structures of the 3 forms of titanium dioxide. Band gaps of selected photocatalyst. Preparation of Zinc Ferrite by hydrothermal method. Photograph of ZnFe2O4 nanoparticles after drying.
Preparation of Zinc Ferrite doped Titanium Dioxide via hydrothermal method. TiO2@ ZnFe2O4 nanoparticles after drying. Calibration curve of methyl orange at 465 nm. Schematic diagram of transmission electron microscope.
The process TEM characterization. Schematic diagram of ultraviolet-visible spectrometer. UV-Vis spectra of pure ZnFe2O4, TiO2@ ZnFe2O4 and P25 TiO2. hν- (hνF(R∞))2 curve of ZnFe2O4.
TEM images of TiO2@ ZnFe2O4 nanocomposite. XRD patterns of pure ZnFe2O4, TiO2@ ZnFe2O4 and P25- TiO2. Photocatalytic degradation of MO by P25- TiO2 under UV light. Photocatalytic degradation of MO by TiO2@ZnFe2O4 under UV light.
The effect of spinel ferrite on the degradation of methyl orange under ultraviolet light irradiation (PH=7). Photocatalytic degradation of MO by P25- TiO2 under visible light. Photocatalytic degradation of MO by TiO2@ZnFe2O4 under visible light. The effect of spinel ferrite on the degradation of methyl orange under visible light irradiation (λ = 465 nm).
34 2 n LIST OF TABLES Table 4. P25-TiO2 and TiO2@ZnFe2O4 reacted with methyl orange (PH =7). P25-TiO2 and TiO2@ZnFe2O4 reacted with methyl orange (PH =7). 33 3 n LIST OF ABBREVATIONS Abbreviations Full text content XRD X-Ray Diffraction TEM Transmission electron microscopy MO Methyl orange UV Ultra-violet Vis Visible EHP Electron-hole pairs NHE Normal hydrogen electrode 4 n PART I.
Research rationale Environmental pollution over the world is the greatest problem that human will face in the 21 st century. Population explosion, the process of industrialization and urbanization, strengthening of agricultural and industrial activities are the leading cause of environmental pollutant and destroy the ecosystem. Water has a very important role for human life as well as other produce activities. However, the pollution of the water environment is becoming serious when dye synthesis, electroplating, pulp and paper mills, printing, food, cosmetic and textile are major source of contamination responsible for the continuous water pollution.
Heterogeneous photocatalysis has been widely used to remediation environmental pollutants. Titanium dioxide (TiO2) is one of the most widely used for photocatalyst due to high photoactivity, low cost, non toxicity and good chemical and thermal stability and strong oxidizing power. However, titanium dioxide is a wide band gap semiconductor and can only absorb about 5% of sunlight in the ultra-violet region, which greatly limits its practical applications (Cheng et al. Recently, it has been found that spinel zinc ferrite, ZnFe 2O4, is a narrow bandgap semiconductor.
Because of it is sensitivity to visible light, so it has a potential application in the conversion of sunlight. However, zinc ferrite has lower valence band potential and poor property in photoelectric conversion. Therefore, it cannot be used in the photocatalytic degradation of organic pollutants (Kaur, 2012). Titanium dioxide has high photoactivity under ultra-violet light irradiation, while zinc ferrite is susceptible to visible light.
So the doping of these 5 n two semiconductors may produce a new nanomaterial capable to absorb with visible light and ultraviolet light and have the potential for waste water purification through utilization of solar energy (Jeremy, 2005). Considering all aspects and issues mentioned above, I propose research:" Titanium dioxide doping zinc ferrite with enhanced ultraviolet and visible light photoactivity for methyl orange degradation". Research objective The primary objective of the study is synthesis and explores the potential of zinc ferrite nanoparticles doping titanium dioxide for the remediation of industrial dye waste. The characteristics of nanocomposite materials were determined by XRD, TEM and UV-Vis spectroscopy.
To assess efficiency of TiO 2@ZnFe2O4 in photocatalytic degradation of methyl orange dye under visible light and ultra-violet light compared with commercial product P25-TiO2. Research question a) What is the method synthesis of TiO2@ZnFe2O4? What is the purpose of using this method? b) What are the advantages of ZnFe2O4 doping on the photocatalytic actives of TiO2? c) What is the effect of TiO2@ ZnFe2O4 on the degradation of methyl orange? 1. Limitation Because the thesis training time was too short, this research project can not perform many other experiments. Definitions Ferrites: Ferrites are chemical compounds consisting of ceramic materials with iron (III) oxide (Fe2O3) as their principal component.
A ferrite is formed by the reaction of ferric oxide (iron oxide or rust) with number of other metals, it including magnesium, aluminum, barium, manganese, copper, nickel, cobalt, zinc, or even iron itself (Kaur, 2012 ) Spinel structure: Spinel is an important class of mixed-metal oxides, which has the general chemical composition of AB2O4. Normally A is a divalent atom such as Mg, Fe, Mn, Zn, and Cu. and B is a trivalent atom such as Ti, Fe, Al, and Co. The structure consist of a cubic closed-packed array of 32 oxide ions, which forms 64 tetrahedral holes and 32 octahedral holes in one unit cell (containing eight formula units (AB2O4 )8) (Kaur, 2012) Methyl orange (MO): Methyl orange dye is a well known acid/base indicator and is a model of a series of common azo-dyes.
The structure of MO dye (Fig 1.1) consists of two benzene rings connected by an azo group, in which one of the rings contains a dimethyl amine and the other contains a sulfonic acid group. The degradation of MO dye is commonly studied as model compound to determine photocatalytic activity (Erik et al. Structure of methyl orange dye (Erik et al. 7 n Photocatalysis: Photocatalysis can be defined as the acceleration of a chemical reaction by either direct irradiation or by the irradiation of a catalyst that in turn lowers the activation energy for the primary reaction to occur (Wade, 2005).
A process which utilize photo (UV/Visible) to activate photocatalyst such as semiconductors, to induce pollutant undergoing reduction or oxidation Semiconductor + light (e-, h+) 8 n PART II. Overview of Titanium dioxide 2. Titanium oxidation structures and properties Titanium dioxide (TiO2) exists as three different polymorphs: anatase, rutile and brookite (Shanon, 2012).1 show the crystal structure of the crystal structure of the three forms of titanium dioxide. Crystal structures of the 3 forms of titanium dioxide (Shanon, 2012) All three polymorphs can be readily synthesized in the laboratory and typically the metastable anatase and brookite will transform to the thermodynamically stable rutile upon calcination at temperatures exceeding 600ºC (Kaur, 2012).
The primary source and the most stable form of TiO2 is rutile. Titanium dioxide is typically an n-type semiconductor due to oxygen deficiency. The band gap is 3.2 eV for anatase, 3.0 eV for rutile, and ∼3.2 eV for brookite and Anatase and rutile are the main polymorphs ( Pelaez et al. The photocatalytic activity of TiO2 TiO2 is the most widely investigated photocatalyst due to high photo-activity, low cost, low toxicity and good chemical and thermal stability (Jeremy, 2005).
Titanium dioxide has high photoactivity and superior property in photoelectric 9 n conversion. The degradation of pollutants is highly correlated with the photocatalytic activity of TiO2 (Dionysios et al. However, TiO2’s band gap is large so it is favorable for ultraviolet photocatalysis while it is highly inefficient for visible light applications that greatly limits its practical applications (Cheng et al.Titanium dioxide photocatalysis was first used for the remediation of environmental pollutants in 1977. This led to a dramatic increase in the research in this domains because of the potential for water and air purification through utilization of solar energy.
Extensive efforts have been made in the development of titanium oxide photocatalyst that can efficiently utilize sunlight or indoor light (Pelaez et al. Increasing the photoactivity of pure TiO2 On a general level, there are three rudimentary parameters that affect the photocatalytic activity of any photocatalyst including TiO 2: its light absorption spectrum and coefficient, the rate of redox reactions that occur at its surface, and the rate or probability of electron-hole pairs (EHP) recombination within the semiconductor (Sesh et al.