The grain size of the rutile-type nano-SnO2 was calculated to be 4.5 nm using XRD. The antimicrobial activity of the developed four nanomaterials; nano-SnO2, Sn(OH)4 nanofluid and Ag doped SnO2 particles were tested.
Theoretical aspects of characterization and investigation techniques
Chapter Two Experimental Pages
Determination of thermal conductivity of Sn(OH) 4 nanofluid using thermal conductometer
Experimental procedure of the study of antimicrobial activities of synthesized nanomaterials
Development of transparent conducting oxide (TCO) 86
Chapter Three Results and Discussions Pages
Thermal conductivity of Sn(OH) 4 nanofluid 118
Bacterial cell structure.(a) A Gram-positive bacterial cell wall is composed of a thick and multi-layered peptidoglycan (PG) coat outside the cytoplasmic membrane. Elements in an EDX spectrum are identified by the energy content of the X-rays emitted by their electrons as these electrons are transferred from a higher energy shell to a lower energy shell.
List of Tables
Background and present state of the problem
Tin oxide (SnO2) nanoparticles are one of the attractive materials due to their wide applications. The main objective of the study was to develop a new, simple and efficient method for the preparation and characterization of nanosized SnO2 as particles and liquid.
Nanomaterials
- The sources of nanomaterials
- Advances in Nanomaterials
- Classification of Nanomaterials
- Examples of Nanomaterials
Siegel: zero (atomic clusters, filaments, and cluster assemblies), one (multilayer), two (ultrafine-grained overlying layers or buried layers), and three (nanophase materials consisting of nanometer-sized equiaxed grains) as shown in Figure 2. Nanomaterials (gold, carbon, metals , metaoxides and alloys) with different morphologies (shapes) are depicted in Figure 3.
Why are nanomaterials important?
Magnetic nanocomposites have been used for mechanical power transmission (ferro-fluids), for high-density information storage and magnetic refrigeration. v) Nanostructured metal clusters and colloids of mono- or pure metallic composition have a particular influence in catalytic applications. Enantioselective catalysis was also achieved using chiral modifiers on the surface of nanoscale metal particles. vi) Nanostructured metal oxide thin films are receiving growing attention for the realization of gas sensors (NOx, CO, CO2, CH4 and aromatic hydrocarbons) with increased sensitivity and selectivity.
Nanomaterial - synthesis and processing
- Methods for creating nanostructures
- Sol-gel process
Removal of liquid from the sol produces a gel, and the sol/gel transition controls the size and shape of the particles. Gel drying, when water and other volatile liquids are removed from the gel network.
Properties of Nanomaterials
- Optical properties
- Electrical properties
- Mechanical properties
- Magnetic properties
Reduced imperfections are also an important factor in determining the properties of the nanomaterials. With the Cd-Se semiconductor nanoparticles, a simple change in size changes the optical properties of the nanoparticles.
Selected Application of nanomaterials
- Fuel cells
- Catalysis
- Phosphors for High-Definition TV
- Next-Generation Computer Chips
- Elimination of Pollutants
- Sun-screen lotion
- Sensors
However, the gate is p-doped and its presence has the effect of depleting the number of electrons in the region of the nanowire below the gate. Sensors rely on the highly active surface to initiate a reaction with minimal change in the concentration of the species to be detected.
Important feature on tin(IV) oxide 1. Short description on tin(IV) oxide
- Phonon modes of stannic oxide
- Crystal structure and surface composition (low index surfaces) of stannic oxide (SnO 2 )
- Surface chemistry of SnO 2
- General remarks on molecular reactions at SnO 2 surfaces
- Amphoterism
- Comparison between stannic and stannous oxide
The silent modes correspond to vibrations of the Sn and O atoms in the direction of the c-axis (B1u) or in the plane perpendicular to this direction (A2g). Thus, various surface reactivities can be explored on the SnO2 surfaces depending on the coordination environment and the charge state of the Sn cation.
Applications of tin oxide
- Transparent conductors
- Heterogeneous catalysis
- Solid state gas sensors
In the next three subsections we attempt to provide a brief overview of the current knowledge of the key properties of SnO2 and related materials that make them suitable for these applications. SnO2 belongs to the important family of oxide materials that combine low electrical resistance with high optical transparency in the visible range of the electromagnetic spectrum. In all applications of the material, the charge carrier concentration and thus the conductivity is further increased by extrinsic dopants.
In this mechanism, the molecules are oxidized by consuming lattice oxygen from the oxide catalyst, which in turn is reoxidized by oxygen in the gas phase. However, the dispersive conduction band with its minimum at the C-point and the high mobility of the charge carriers ensure that a change in the charge carrier concentration results in a strong change in the electrical conductivity of the material.
The concept of Nanofluid
- Theoretical study of nanofluid thermal conductivity
- Experimental study of nanofluid thermal conductivity
- Experimental study of nanofluid heat transfer
- Potential applications and benefits of nanofluids
- Improved Heat Transfer and Stability
- Reduced Pumping Power
- Minimal Clogging
- Miniaturized Systems
- Cost and Energy Savings
- Technology for production of nanofluids
- Measurement of Viscosity
- Synthesis and Preparation of Nanofluid
- The Single-step Process
- The Two Step Process
Therefore, the thermal conductivity of fluids containing suspended metallic solid particles can be expected to be significantly higher than that of conventional heat transfer fluids. This discovery theoretically shows the possibility of nanofluids, i.e., metal nanoparticles are able to significantly increase the thermal conductivity of conventional heat transfer fluids. The increased thermal conductivity will result in higher heat transfer than that of the base (pure) fluid without dispersed nanoparticles.
Measurements of heat transfer coefficients of nanofluids have shown that the heat transfer capability of water increased by 15% with a distribution of less than 1% volume of copper oxide nanoparticles [89]. However, the addition of dispersants can affect the heat transfer performance of nanofluids, especially at high temperatures i.e.
Antimicrobial activity of nanoparticles (NPs)
- Improvement of antimicrobial properties to classical antimicrobial agents by Nanoparticles
- Mutual interaction of nanoparticles and antimicrobs
- Role of the cell wall
- Role of the NP type and surface
- Role of microbs growth rate
- Role of biofilm formation
These are the role of the cell wall, the role of NPs types and surface, the rule of microbial growth rate and the role of biofilm formation. The outer membrane of Gram-negative bacteria often confers resistance to hydrophobic compounds including detergents and contains as a unique component lipopolysaccharides, which increase the negative charge of cell membranes and are essential for the structural integrity and viability of the bacteria (Figure 16b) [125]. The structure of the cell wall plays an important role in the tolerance or susceptibility of bacteria in the presence of NPs. Species susceptibility is not only related to the structure of the cell wall in Gram-positive and Gram-negative bacteria [128].
One of the major shortcomings of antibacterial agents and NPs is their failure to fight with bacteria [e.g. S. Biofilms are known to be a significant problem because biofilm formation protects pathogenic bacteria against antibiotics and is one of the main causes of the development of chronic infections [135].
Theoretical aspects of characterization and investigation techniques
- Scanning Electron Microscope (SEM) and Energy dispersive X-ray EDX analysis
- Scanning Electron Microscope (SEM) Technique
- Energy dispersive X-ray (EDX)
- X-ray diffraction
- Metallography and Optical microscopy
- Thermo & Differential Gravimetric Analysis (TGA/DTA)
- Thermogravimetric analysis or thermal gravimetric analysis (TGA)
- Differential gravimetric analysis (DTA)
- Thermal conductometer of (nano) fluid/liquid
The design and function of the SEM are very similar to the EPMA and there is significant overlap in capabilities between the two instruments. It is a technique used to identify the elemental composition of the sample, or a region of interest thereof. Elements in an EDX spectrum are identified based on the energy content of the X-rays emitted by their electrons when these electrons transition from a higher energy.
Light microscopes are designed for placing the smooth surface of the sample on the sample stage, either upright or inverted. The area under a DTA peak is the enthalpy change and is not affected by the heat capacity of the sample.
Chemicals and equipment 1. Chemicals
- Equipment used in the experiments
Synthesis
- Synthesis of Sn(OH) 4 nanofluid
- Synthesis of SnO 2 nanoparticle
- Synthesis of Ag doped SnO 2 nanoparticles
Next, the white residue was dried at 100°C and ground with a mortar and pestle to obtain powder. 50 ml of the synthesized liquid and 10 ml of concentrated nitric acid (65%) were mixed and refluxed until the mixture boiled off. Then, an appropriate amount of AgNO 3 (1:3 and 1:5 molar ratio of Ag and Sn to synthesize two products) was added into the boiling mixture and the boiling was continued for the next 15 minutes and the mixture was cooled at room temperature.
During the addition of the NaOH solution, the bright white mixture turned into a deep coffee-colored gel. The gel was washed 15 times with ultrapure water and dried under a vacuum evaporator (100 mbar, 80oC). Then, the dried deep coffee-colored residue was ground with a mortar and pestle to obtain a powder and finally heated at 600 oC for 3 h to produce the desired nano-Ag doped nano-SnO2.
Identification techniques 1. X-ray diffraction Experiment
- SEM and EDX Experiments
- Experiments of other characterization techniques
A 2θ scan was taken from 10° to 70° to obtain possible fundamental peaks with the pitch of 0.020 and time for each step data acquisition 2.0 sec. The morphology of the synthesized materials and their energy dispersive X-ray spectra were investigated using a field emission scanning electron microscope (FE-SEM) (JSM-7600F, JEOL, Tokyo, Japan). UV-visible spectroscopy, FT-IR, TGA/DTA and metallography and optical microscopy (MOM) were also used and their manufacturers' recommended experimental procedures were followed.
Determination of viscosity of Sn(OH) 4 nanofluid
The clearance was small to prevent natural convection in the fluid and the fluid was presented as alumina with area πdml and thickness Δr for heat transfer from the plug to the jacket. The plug was made of aluminum and contained a cylindrical heating element whose resistance at operating temperature was accurately measured. Due to the positioning of the thermocouples and the high thermal conductivity of the materials involved, the measured temperatures were in fact the temperatures of the hot and cold faces of the liquid lamina.
A small keypad connected the flexible cables to the plug/jacket assembly and provided control of the voltage supplied to the heating element. An analog voltmeter enabled determination of the input power, and a digital temperature indicator with a resolution of 0.1 K displayed the temperature of the plug and jacket surfaces (Figure 26, see introduction chapter).
Experimental procedure of the study of antimicrobial activities of synthesized nanomaterials
- Bioassay
- Antimicrobial Assay
The diameter of the halozone was measured and the result was expressed as the mean ± standard error of three replications of each dose of each compound.
Development of transparent conducting oxide (TCO)
Characterization of synthesized nanoparticles 1. Characterization of SnO 2 nanoparticle
- XRD of SnO 2 (Data treatment and calculation)
- SEM and EDX of nano-SnO 2
- FT-IR of nano-SnO 2
- UV-Visible spectroscopy of nano-SnO 2
- Characterization of Sn(OH) 4 nanofluid
- DLS study on Sn(OH) 4 nanofluid
- FT-IR of Sn(OH) 4 nanofluid
- UV-Visible spectroscopy of (SnOH) 4 nanofluid
- Characterization of Ag doped SnO 2 nanoparticles
- XRD of Ag doped SnO 2 (Ag:Sn = 1:3) [Data treatment and calculation]
- XRD of Ag doped SnO 2 (Ag:Sn = 1:5) [Data treatment and calculation]
- Findings on XRD of Ag doped SnO 2
- SEM and EDX of Ag doped SnO 2 nanoparticles
- FT-IR of Ag doped SnO 2 nanoparticles
- UV-Visible spectroscopy of Ag doped SnO 2 nanoparticles
The corresponding graph of the data in the above tables is given in Figure 45. The corresponding graph of the data given in the above tables is given in Figure 49. The data determined the reaction pattern involved in the formation of the two products as well.
In addition, the lattice parameters of the nanoparticles (SnO2 and Ag in both compounds) were calculated from N.R. SEM was used to determine the morphology of the synthesized Ag-doped SnO2 nanoparticles.
Thermal conductivity of Sn(OH) 4 nanofluid
These two peaks may occur due to different sizes of Ag nanoparticles (Ag: 11.03 nm in a 1:3 compound and Ag: 22.28 nm in a 1:5 compound) present in the two compounds .
Viscosity of Sn(OH) 4 nanofluid
Development of transparent conducting oxide (TCO)
In addition, metallographic and optical microscopy images (Figure 71 [A, B, C, D, E, F, G, and H) were used to examine the surface of the TCO. Both SEM and optical microscopy images revealed that the surfaces of the TCO had a smooth and planar texture. Similarly, Ag-doped SnO2 nanoparticles were used to develop the same type of TCOs, but no TCOs were developed that formed rather colored solid thin films.
Antimicrobial activities of nano-SnO 2 , Sn(OH) 4 nanofluid and Ag doped SnO 2 nanoparticles
- Antimicrobial activities of Ag doped SnO 2 nanoparticles
- Effect of Ag-SnO 2 nano particles on Bacterial Pathogen (Fish Pathogen) EP-10
- Effect of Ag-SnO 2 nano particles on strawberry pathogen P-25
- Effect of Ag-SnO 2 nano particles on Fungus (strawberry pathogens) CG-12
- Effect of Ag-SnO 2 nano particles on Fungus (strawberry pathogens) CG-33
- Major findings and remarks on antimicrobial activities of Ag doped SnO 2 nanoparticles
Some significant results were found from the study on the antimicrobial activities of Ag doped SnO2 nanoparticles. To summarize the result, a comparison of the effects on the four microbes is given in Table 24. On the other hand, a clear selectivity of the two nanomaterials was observed for Fungi (strawberry pathogens) of CG-12 and CG-33.
With XRD, the diameter of the grains of the nano-SnO2 and lattice parameters were measured. Using the nanofluid as a starting material, Ag-doped SnO2 nanomaterials were synthesized where the size of the nano-Ag was controllable.
Data treatment & calculation of thermal conductivity of Sn(OH) 4 nano fluid
Data treatment & calculation for determination of viscosity of Sn(OH) 4 nanofluid
