evaluation of sterilization possibility in water environment of activated nano mno2 coated on calcined laterite

ĐẠI HỌC QUỐC GIA HÀ NỘI TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN Cao Việt EVALUATION OF STERILIZATION POSSIBILITY IN WATER ENVIRONMENT OF ACTIVATED NANO MnO 2 COATED ON CALCINED LATERITE CHUYÊN NGÀNH: QUẢN LÝ CHẤT THẢI VÀ XỬ LÝ VÙNG Ô NHIỄM (CHƯƠNG TRÌNH ĐÀO TẠO QUỐC TẾ) LUẬN VĂN THẠC SĨ KHOA HỌC GIÁO VIÊN HƯỚNG DẪN: PGS.TS. TRẦN HỒNG CÔN Hà Nội - 2011 Table of contents Abbreviation i List of Figures ii List of Tables iii Chapter 1 1 INTRODUCTION 1 1.1 Water situation in general 1 1.2 Water sterilization 3 1.2.1 Boiling 4 1.2.2 Chlorine 5 1.2.3. Ozone 5 1.2.4 Ultraviolet light 6 1.2.5 Hydrogen peroxide 7 1.2.6 Solar disinfection 7 1.2.7 Photocatalysis on semiconductors 7 1.2.8 High speed water sterilization using one-dimensional nanostructures 7 1.3 Nanotechnology 8 1.4 Manganese dioxide 10 1.5 Laterite 11 Chapter 2 13 OBJECTIVES AND RESEARCH METHODS 13 2.1 Objectives 13 2.2 Materials and Research methods 13 2.2.1 Material and instruments 13 2.2.2 Research methods 14 2.2.2.1 Synthesis of nano MnO 2 adsorbents 14 2.2.2.3 Investigation of sterilizing capability of nano MnO 2 adsorbents 15 Chapter 3 17 RESULTS AND DISCUSSION 17 3.1 Synthesis of nano MnO 2 adsorbents 17 3.2 Investigation of sterilizing capability of nano manganese dioxide 23 3.2.1 Investigation in static condition 24 3.2.2 Investigation in dynamic condition 28 3.3 Mechanism of sterilization of MnO 2 coated on calcined laterite in water 33 3.3.1 Investigation the influence of Mn 2+ in sterilizing capability 33 3.3.2 Examine the mechanism of sterilization of MnO 2 35 Chapter 4 38 CONCLUSION 38 REFERENCES 40 i Abbreviation MD Manganese Dioxide UV Ultraviolet DNA Deoxyribonucleic Acid SODIS Solar Disinfection CNT Carbon Nanotube AgNWs Silver Nanowires‟ TEM Transmission Electron Microscopy SEM Scanning Electron Microscope EPA Environmental Protection Agency E. coli Escherichia coli BRM Bacteria removing material MPN Most probable number EBCT Empty Batch Contact Time ii List of Figures Figure 1: Nanoscale materials 10 Figure 3: Coating process 18 Figure 4: MnO 2 nanoparticles with the magnification of 40000 times 19 Figure 5: MnO 2 nanoparticles with the magnification of 60000 times 20 Figure 6: MnO 2 nanoparticles with the magnification of 100000 times 21 Figure 7: Creation of adsorbent coating by nano MnO 2 particles (100k) 22 Figure 8: Creation of adsorbent coating by nano MnO 2 particles (200k) 22 Figure 9: Shaking equipment for static condition investigation 23 Figure 10: Column device for dynamic condition investigation 24 Figure 11: Samples in contact time‟s influence experiment 25 Figure 13: Samples in BRM/water ratio‟s influence experiment 27 Figure 14: Samples in BRM/water ratio‟s influence experiment 28 Figure 15: Model of column device 29 Figure 16: Samples in flow rate in BRM column‟s influence experiments 30 Figure 17: Influence of flow rate on bacteria sterilizing in BRM column 30 Figure 18: Samples in the experiments 32 Figure 19: Influence of column height on bacteria sterilizing in BRM column 32 Figure 21: Influence of Mn 2+ in sterilizing capabilities 35 iii List of Tables Table 1: Influence of contact time on bacteria sterilizing 24 Table 2: Influence of the ratio of BRM and water on bacteria sterilizing 27 Table 3: Influence of flow rate on bacteria sterilizing in BRM column 29 Table 4: Influence of column height on bacteria sterilizing in BRM column 31 Table 5: Influence of Mn 2+ in sterilizing capabilities 34 Chapter 1: Introduction 1 Chapter 1 INTRODUCTION 1.1 Water situation in general Water is one of the world‟s most essential demands for human life, and the origin of all animal and plant life on the planet. Civilization would be impossible without steady supply of fresh and pure water and it has been considered a plentiful natural resource because the sensitive hydrosphere covers about 75% of the Earth's surface. Its total water content is distributed among the main components of the atmosphere, the biosphere, oceans and continents. However, 97% of the Earth's water is salty ocean water, which is unusable for most human activities. Much of the remaining 3% of the total global water resource, which is fresh-water, is locked away in glaciers and icebergs. Approximately 20% of the freshwater resources are found as groundwater, and only 1% is thought to be easily accessible surface water located in biomass, rivers, lakes, soil moisture, and distributed in the atmosphere as water vapor. [1] In the process of rapid development of science and technology, the demand for pure water is increasing to serve multifarious purposes in different types of industries. Global water consumption raised six folds in the past century, double the rate of population growth. In addition, the boom in world‟s population during recent decades, has contributed to the dramatically rising demand of pure water usage for both household and industrial purposes. The high population density and industrialization speed have triggered the hydrosphere to be polluted with inorganic and organic matters at a considerable rate. Moreover, to satisfy the food demand, a number of harmful chemicals such as pesticides and herbicides Chapter 1: Introduction 2 are used in order to improve the productivity in agricultural production, which also causes the scarcity of clean resources. [1] The contamination of ground water (mostly by toxic metal ions due to both natural and anthropogenic reasons) is also one of concerning issues on clean water. It is necessary to assess the quality of water used in industry, household activities and drinking purpose. Understanding of the importance of clean water in human life, many countries has gradually adjusted their environmental regulations more stringently to reserve clean water resources. With the purpose of overcoming the water pollution problems, and to meet the stricter environmental regulations, scientists and researchers have focused on improving exist water purification processes and approaching to alternative water treatment technologies as well, so as to increase the efficiency of those decontamination methods. It is surveyed that human awareness about the seriousness of water pollution has enhanced over the world. People have also started realizing that water is not an unlimited resource, hence it needs to be protected and smartly used. An ideal water treatment process should have the capability to mineralize completely all the toxic organic components without leaving behind any harmful by-products and to recover all toxic metals from wastewater. In broader classification, biological, mechanical, thermal, chemical or physical treatments, or their combinations may be applied to purify contaminated water. The choice of the proper water treatment processes depend on the nature of the pollutants presenting in water, and on the acceptable contamination level in treated water. There are two main purposes of water treatment study – the reduction of contaminant level in the discharged stream to meet environmental standards, and Chapter 1: Introduction 3 the purification of water to ultrapure water in order to be able to use in semiconductor, microelectronic and pharmaceutical industries. Moreover, the cost or effectiveness of the water treatment processes also plays a significant role in choosing a particular one. Biodegradation, adsorption in activated carbon, air stripping, incineration, ion-exchange, coagulation-precipitation, membrane separation, thermal and catalytic oxidation, oxidation by permanganate, chlorine, ozone and hydrogen peroxide are widely applied in conventional water treatment processes for organic and inorganic pollutant containing water. Besides advantages, each process has their own shortcomings which are being improved gradually via new technologies. [1, 2] 1.2 Water sterilization Water sterilization technology is useful in various ways for our daily life. For example, it is used in water and sewerage systems treatment. Methods commonly used for sterilization include chemicals, heat, ultraviolet (UV) radiation, and ozone. Chemicals (chlorine, peroxide, etc.) are utilized extensively for sterilization because of their simplicity; however, they probably form unexpected effects, such as modifying the quality of the target. In addition, sterilization by chlorine usually generates odorous substances and bio-hazardous materials. [2] It is not totally accurate to assess whether water is of an appropriate quality only by visual examination. Simple procedures such as boiling or the use of a household activated carbon filter are not sufficient for treating all the possible contaminants that maybe present in water from an unknown source. Even natural spring water – considered safe for all practical purposes in the 1800s – must now be tested before determining what kind of treatment, if any, is needed. Chemical Chapter 1: Introduction 4 analysis, while expensive, is the only way to obtain the information necessary for deciding on the appropriate method of purification. [3] Simple techniques for treating water at home, such as chlorination, filters, and solar disinfection, and storing it in safe containers could save a huge number of lives each year. Sterilization is accomplished both by filtering out harmful microbes by and also adding disinfectant chemicals in the last step in purifying drinking water. Water is disinfected to kill any pathogens which pass through the filters. Possible pathogens include viruses, bacteria, including Escherichia coli, Campylobacter and Shigella, and protozoa, including Giardia lamblia and other cryptosporidia. In most developed countries, public water supplies are required to maintain a residual disinfecting agent throughout the distribution system, in which water may remain for days before reaching the consumer. Following the introduction of any chemical disinfecting agent, water is usually held in temporary storage - often called a contact tank or clear well to allow the disinfecting action to complete. [4] 1.2.1 Boiling Boiling is an easy, cheap and common way to eliminate contaminations and microorganisms in developing countries, but this method is only practical for small amounts. When the water has boiled for 5 – 10 min all the pathogens have been killed and the water is safe to drink. [2] The main disadvantage of this method is that it requires a continuous source of heat and appropriate equipment. [...]... purposes in this part: One is to examine whether the mechanism of sterilization of MnO2 coated on calcined laterite is influenced by the high oxidation potential of MnO2 The other is to survey the effects of Mn2+ on sterilizing process of MnO2 by changing the concentration of Mn2+ 16 Chapter 3: Results and Discussion Chapter 3 RESULTS AND DISCUSSION 3.1 Synthesis of nano MnO2 adsorbents Working solution of. .. addressed as follows: - To synthesize MnO2 nanoparticles coated on calcined laterite; - Analyzing of MnO2 nanoparticles formation portion and its physical structure; - To investigate the sterilization possibilities of created material; - To examine the mechanism of sterilization of MnO2 coated on calcined laterite in water 2.2 Materials and Research methods 2.2.1 Material and instruments All chemicals were... 2.2.2.3 Investigation of sterilizing capability of nano MnO2 adsorbents The routine monitoring of the bacteriological quality of drinking water relies on the use of the indicator organisms Escherichia coli (E coli) and coliforms which are used to indicate fecal contamination or other water quality problems such as failures of disinfection, bacterial regrowth within the distribution system or ingress... was binding energy, was there reformation of nanoparticles or inactivation, etc That confusion should be investigated in following time 3.2 Investigation of sterilizing capability of nano manganese dioxide In this research, total coliform was chosen as indicating bacteria for all bacterial removing investigation The bacteria number was determined in the initial water sample and followed the time of sterilizing... formed by ozonation, it has been discovered that the use of ozone produces a small amount 5 Chapter 1: Introduction of the suspected carcinogen bromate, although little bromine should be present in treated water Another of the main disadvantages of ozone is that it leaves no disinfectant residual in the water Ozone has been used in drinking water plants since 1906 where the first industrial ozonation plant... characterized using Scanning Electron Microscope (SEM) to obtain information on its physical structure Consequently, the coating process was carried out as shown in Figure 3 17 Chapter 3: Results and Discussion Dried laterite grains Nano solution Soaking Sucking excess liquid Drying Washing Drying Figure 3: Coating process The TEM images of MnO2 nanoparticles solution clearly reveal the presence of a large... sterilizing process Static and dynamic condition were chosen to conduct the experiments Figure 9: Shaking equipment for static condition investigation 23 Chapter 3: Results and Discussion Figure 10: Column device for dynamic condition investigation 3.2.1 Investigation in static condition 3.2.1.1 Influence of detention time on bacteria sterilizing Detention time is an important parameter to determine the... some inorganic (e.g CN- ions) compounds For more than ten years the interest of scientists has turned into application of the heterogeneous photocatalytic methods to water detoxification [6] 1.2.8 High speed water sterilization using one-dimensional nanostructures One-dimensional nanostructures have been extensively explored for a variety of applications in electronics, energy and photonics Most of these... material and water sample were chosen as fundamental parameters Therefore, other parameters which affect the alteration of contact time and the ratio between material and polluted water sample, such as the column height, the flow rate, etc in the dynamic condition, were taken into consideration 2.2.2.4 Examine the mechanism of sterilization of MnO2 coated on calcined laterite in water There are two main purposes... coating, the surface of laterite was quite smooth; but after coating there were nanoparticles of MnO2 in barbed sphere shape distributed tight all over laterite surface 22 Chapter 3: Results and Discussion The clinging of MnO2 nanoparticles on calcined laterite surface was recognized for application purpose, but the essence of this phenomenon was not determined so far There may were any chemical bond, . Investigation of sterilizing capability of nano manganese dioxide 23 3.2.1 Investigation in static condition 24 3.2.2 Investigation in dynamic condition 28 3.3 Mechanism of sterilization of. MnO 2 coated on calcined laterite in water 33 3.3.1 Investigation the influence of Mn 2+ in sterilizing capability 33 3.3.2 Examine the mechanism of sterilization of MnO 2 35 Chapter 4 38 CONCLUSION. TỰ NHIÊN Cao Việt EVALUATION OF STERILIZATION POSSIBILITY IN WATER ENVIRONMENT OF ACTIVATED NANO MnO 2 COATED ON CALCINED LATERITE CHUYÊN NGÀNH: QUẢN LÝ CHẤT THẢI