lời mở đầu, tỉnh hình vít tải Việt Nam, kết luận chung. -_ Chỉnh sửa sai lệch don vi. Ngày tháng năm Giáo viên hướng dẫn Tác giá luận văn CHU TICH HOI DONG DECLARATION IN LIEU OF OATIL By “Duong Nguyen Thi Thuy” ‘This is to confirm my Master ‘thesis was independently composed/authored by myself using solely the referred sources and support additionally assert that this Thesis has not been part of another examination process ACKNOWLEDGEMENT I would first like to sincerely express my thankfulness to my supervisors, Prof. Dang Kim Chi, Dr.
Dirk Hollmam of Institute for Chemistry at Rostock University and Dr. Ly Bich Thuy at Institute for Environmental Science and Technology. Dang Kim Chi was very willing lo spend her time on discussing wilh me and give me Imowledgeable advices and support whenever | ran into troubles and steer me to the right direction of my thesis. Dirk Hollman thoroughly instructed me a lot of experiment skills in laboratory and always supported ine during my lime researching in Germany.
Ly Bích Thuy is a person always providing me valuable comments and feedback with her high responsibility and expertise on my work from time totime io help me carry oul the scientific work wilh high efficiency Tam also gratelisl fo faculty of School of the Fnvirommental Scicnec and Technology - Hanoi University of Science and ‘Technology who enthusiastically guided, taught and helped me during the process of studying, researching and completing this thesis. also would like to thank Prof. Le Minh Thang and ROILAN Project - Rostock - Hanoi DAAD SDG Graduate School and all colleagues at Technical Chemistry Group, University of Rostock for supporting and creating favourable conditions for me to attend the Master Research Exchange Program at the Institute for Chemistry, University Rostock, Germany Finally, my great. gralilude is for my family and my friends who always believed and encouraged me so much during, my years of study.
This achievement would not have been possible without them, Author, Duong Nguyen ‘thi Thuy ABBREVIATION Absorbance PMRs Pholovalalytic membrane reactors MB Methylene blue XRD X-Ray Diffraction RC Regenerated Cellulose ICP-MS Inductively coupled plasma mass spectromety UV Ultraviolet VIS Visible Mw Molecular weight SPR Surface Plasmon Resonance PTEE Poly ‘Tetra Fluorethylene Ti0; Tianium đioxiđe Au/TiOs Gold nanoparticles deposited on titanium dioxide TABLE OF CONTENTS DECLAR.ATION IN LIEU OF OATH.ce iv ABBREVIATION. a wo TAHLE OF CONTUNTS. TARLE OF FIGURES. HH HH eeriere a TABLE OF TABLES INTRODUCTION.
Introduction about photocatalyst 1. Overview of photocatalyst 1. Introduction about titanium dioxide 13. Gold nanoparticle supported on titanium dioxide (Aw/TiO2) 2.
Photocatalytic membrane reactor 2. Research works on photocatalytic membrane reactor. 3, Researches and application of AwTiO2 in water treatment 4, Organic pollutant status. Experimental seơtioi.
so cào 2t sec 1. Chemical and materials 2. Synthesis of Aw’TiO, photocatalyst 2. AwTiOx characteristic analysis method 2.
into membrane surface 2. Design and construction of a PMR rcactor.4, valuation of the system in removal of organic matter from feed water. Evaluation of batch reaetion. livaluation of suspended reaclion.3, Evaluation of muưnobnlized syslemL Chapter 3.
Resulls and Discussion. Characteristics of photocatalyst:. 2, Coating AwLiQ2 on membrane surface eee 3, Evaluation of photocatalyst in batch reaction. livaluation of suspended PMR.
Tivaluation of imưnobilized PMR. CONCLUSIONS RECOMMENDATION REFERENCES ANNEX TABLE OF FIGURES Figure 1. Crystal structure of titanium dioxids phases of rutile, brookile and artalase (anzeer, 2013). Mechanism of photocatalytic reaction (Xu, Rangaiah, & Zhao, 2014).
Comparison between TiO2 and Au/TiO? reaction 16 Figure 4. The number of publications on the topic of PMR and PMR for water treatment. Annual average BODs content in majer rivers in Vietnam (2005-2009). Process of study experiment.
Diagram of Au/TiO2 synthesis process - - 30 Figure 8. Spraying Au nanoparticles on membrane surface. Schematie diagram of a lab-scale PMIR system. Schematic diagram of (a) tangential (crass) flow filtration and (b) dead— end filtration (HI Safty & Hoa, 2012).
UV-VIS absorbance of Au/TiQ2 photocatalyst - 37 Figure 12. Performance of Photocatalyst in different concentration - 40 Figure 13. Performance of different membrane MW at different amount of Aw‘liO2 Al Figure 14. Performance during the reaction time 42 Vigure 15.
Performance of different filtration mode im continuous flow.43 TABLE OF TABLES Table 1 Classification of PMRs configuration ‘Table 2. Advantagesand disadvantages of different configurations of PMR. Table 3 Experiments description Table 4. ICP result of Au/TiO2 sample.
Mass of Au/l102 coated in membrane surface Table 6 Solutions used to avoid photo catalysts peeling off the membrane. TNTRODUCTION Water is a unique natural resource playing an essential role in maintaining global ecosystems and quality of life. It is estimated that 97% water on earth is saline while the freshwater makes up only 3% but it is unevenly distributed over the world in different. forms of rivers, lakes, streams or glaciers, ele.
Despile very stall proportion, however, many freshwater bodies nowadays face increasingly serious pollution caused by human activities in various regions. Additionally, freshwater scarcity has happened conunorily over the decades. The causes of water shorlage are selated to climate change, rapid growth of population, increase in water demand for economic sectors ineffective water usage, and mostly quality degradation. In the modern cra, water pollution and contamination are regarded as one of the most substantial and worrisome problems that demands an immediate and practical solution.
According to United Naliou World Water Development (UNWWD) reporL, around 748 million people de not have access to pure drinking water around the world, and the water demand for industrial manufacturing will increase to 400 percent by 2050. ‘Under this context, the importance of development water treatment technologies is largely realized by researchers. Among wide array of water purification methods, photocatalysis has emerged as very promising solution because it requires low cost while showing great efficiency in pollutant removal without dangerous by-products The pholocatalysl-based method itself has derionstrated its effectiveness in trealing wide range of pollutants including organic and inorganic compounds from aqueous or gas phase syslems clean-up. Besides, in order 1o prevent photocalalyst.
from being, snixed with output flow, a scparation process is required. Membrane technology is well-known as an effective and mature method for a wide range of separation applications such as removal of small suspended solids or micro-organism. Thus, iL is reasonable to consider coupling the membrane process with photocatalysis to collect and reuse photocatalysts in the photocatalytic system to create Photocatalysis Membrane Reactar (PMR). This technique has paved the way for researchers to discover and achieve an applicable environmental-friendly solution (o address water pollution issues.
An order to develop a purifier for drinking water with small contaminant concentration at household scale, the study approached a PMR system using photocatalyst activated by visible light In which, the Au/TiO2 photocatalyst is selected 1o be applied. TiO2 is known as high and stable activity catalyst besides its large commercial potential and non-toxic characteristics. However, TiO, is only effective under UV light due to its large band gap (-32cV). Deposition of Au nano-particles on surface of the photocatalyst for purpose of take advantage of Surface Plasmon Resonance (SPR) is chosen to improve the effect of the photocatalytic system under visible irradiation.
This thesis aims to develop a simple configuration of an equipment of photocatalytic anembrane for organic pollutant degradation i walor. Tn order lo achieve the main objective, the following activities were caried out: «Synthesis of Aw’TiO» photocatalyst = Preparation of photocatalyst coated on regenerated cellilose membrane = Fvaluation of two PRM configuration in removal of orgaric matler (Methylene blue) from feed water: suspended system and immobilized system. In the purpose of develop a real device which consists of a combined PMR/pure MR. reactor for purification of drinking water, this study conducted taboratory experiments in degradation of Methylene Bluc.
The research synthosized and evaluated photocatalyst of AuliO: under visible light to approach application of photocatalysis to drinking water teatment in practical condition. Entire process of experiments was carried out at the laboratory at Interdisciplinary Faoulty Life, Light and Matter, Institute of Chemistry, University of Rostock. Introduction about photocatalyst 1. Overview of photocatalyst 1.
Definition of photocatalyst As part of catalysis - and more precisely of heterogeneous catalysis - heterogeneous photocatalysis is an area of chemistry impacting many reactions as varied as oxidation reactions, dehydrogenation reactions, metal deposition, hydrogen transfors, cto. Lleterogencous photocatalysis can be described as the acceleration of photoreaction in the presence of a catalyst. Basically, photocatalysis differentiates from oonventional calalysis by the activalion of the catalytic solid because iL ts aclivated ‘by adsorbing a photon and is capable of accelerating a reaction without being consumed. This photonic activation thus requires the use ofa semiconductor material as calalyst, provided that the radiation wavelengths are greater than ils band gap, which corresponds to the energy gap between both conduct ion and valence bands of the semiconductor.
Generally, the photocatalysis discipline exisls through the ability of a material, usually is semiconductor, to simultancously interact with light and reactants, through both absorption and adsorption phenomena, respectively. ‘here is a wide array of photowalalysl such aa TiQ2 (3,2 €V), SrTiO (3,4 eV), FeaOs (2,2 eV); Cds Œ,5 eV), WO (2,8 eV); ZnS (3,6 eV}, FeliOs (2,8 eV), ZrO2 (5 eV), V20s (2,8 eV): Nb20s (3,4 eV); SnOz (3,5 eV). Applications of photocatalyst Pholavatalyst has beer: provent as art ideal methed whieh can be used for various purposes such as degradation of different organic pollutants in wastewater, purification of air, and antibacterial activity. When compared with other methods, photocatalysis is rapidly growing and gaining more attention from the rescarchers due to its several advantages such as low cost, non-toxicity and attractive efficiency.
Introduction about titanium dioxide 1. History of discovery and research about titanium dioxide Among different kind of photocatalyst, TiQ2 has been most common and widely studied. Photocalalys! has found ils way since in 1972 by Fujishima and Honda when they had discovered Titanium Dioxide (TiO2). During that time, the purpose of TiD2 was for water splitting into hydrogen and oxygen in a photo-5 electrochemical cell.
This discovery has propagaled researchers Lo explore the usage of TiO2 in many arcas especially in photocatalysis. One of the earlier works on photocatalysis for wastewater treatment was conducted by Bahnemann in 1991 using TiO suspensions. They reported on the influence of light intensity, temperature and pH on the degradation rate of halogenated hydrocarbons using, ‘1iO2 photocatalyst suspensions. They have concluded that this technology has a bright potential for wastewater freatmen.
applications and detailed study are needed to further develop this technology. Inspired from this, a lot of research works have been conducted by using TiO: as photocatalyst for many applications because of its characters: chemical stability, nom-toxiciy, low cost, strom: oxidizity: abilities for the decomposition of organic pollutants, superhydrophilicity, long durability, nontoxicity, and transparency to visible light (Nakata & Fujishima, 201). Characteristics of titanium oxide Physival characteristics of TiOz = White powder, tum into yellow at high temperature = Stiffness, melting point is 1870°C = M—79.25 g/em? TiO: have many crystal structures including three main structures which are anatase, brookite and rutile. Anatase ( Rutile Brookite Figure 1.
Crystal structure of titanium dioxide phases of rutile, brookite and anatase (Janzeer, 2013). Mechanism of photocatalytic reaction of titanium dioxide The most commonly assumed photodegradation mechanism of TiO2 is based on Langmuir-Hinshelwood kinetic model. TiO: + hv > h’ +e ht +e" — heat hỶ + (FRO/OH*), OH(aq) e+. Or Reactantso + S <> Reactant OH: + Reactant Products When an electron in the balance band of the semiconductor absorbs a photon with energy greater than the band gap (AE) of the semiconductor, that electron becomes excited and jumps to the conduction band, leaving a positively charged hole in the valence band.
Besides the potentiality to recombines with the electron, the positively charged hole can oxidize water molecules to form hyper-reactive hydroxyl free radicals (OHs). The resulting hydroxyl radicals are the main agent that attack the chemical pollutant molecules or microorganism cells to purify water.