CeO2–ZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards liquid-phase oxidation of benzene.
The document summarizes the synthesis and characterization of chitosan/silver biopolymer nanocomposites. Chitosan/silver nanocomposite films were synthesized using ultrasonication and spin coating methods. The films were characterized using UV-Vis spectroscopy, FTIR, XRD, dielectric measurements, and four probe resistivity measurements. The characterization confirmed the presence of silver nanoparticles embedded in the chitosan polymer matrix. The dielectric constant was found to decrease with increasing frequency. Electrical measurements showed linear current-voltage behavior consistent with Ohm's law. The document concluded the synthesis and characterization techniques provided an understanding of the chitosan/silver nanocomposite materials.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Biopolymer based nanomaterials as potential biosorbents for toxic metal ionsAlexander Decker
This document summarizes a research study on the use of ternary nanoparticles composed of chitosan, yeast, and gelatin for removing toxic copper ions from water. The nanoparticles were characterized using FTIR and TEM analysis. FTIR showed the presence of functional groups from the three biopolymers and shifts upon copper ion adsorption. TEM revealed nanoparticle sizes ranging from 50-150 nm. Batch experiments showed over 90% copper ion removal, with adsorption fitting well to the Langmuir isotherm model. The effects of biopolymer composition, metal ion concentration, pH, and temperature on adsorption capacity were also examined.
Synthesis, characterization and electrocatalytic activity of silver nanorods ...kutty79
This paper describes a simple method of synthesizing silver nanorods using the polyol process, where propylene glycol serves both as a reducing
agent and as a solvent in the presence of a capping reagent such as polyvinylpyrrolidone (PVP). The diameter and length of silver nanorods could be
controlled by changing the AgNO3/PVP ratio. The end-to-end assembly of the silver nanorods was found. The silver nanorods were characterized by
using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and absorption spectroscopy. The catalytic activity of a
glassy carbon electrode with Ag nanorods exhibits extraordinary electrocatalytic activities towards the electro-reduction of benzyl chloride.
Biological and Medical Applications of Graphene NanoparticlesAI Publications
Graphene which is one of the latest additions to nanocarbon family has peculiar band structure, extraordinary thermal and electronic conductance and room temperature quantum Hall effect. It is used in for various applications in diverse fields ranging from catalysis to electronics. In addition to being components in electronic devices, GO have been used in nanocomposite materials, polymer composite materials, energy storage, biomedical applications, catalysis and as a surfactant with some overlaps between these fields Graphene oxide is a unique material that can be viewed as a single monomolecular layer of graphite with various oxygen containing functionalities such as epoxide, carbonyl, carboxyl and hydroxyl groups.
Electrochemical Synthesis of MoO3 Nanoparticles Effect of Temperature Convert...IJERA Editor
MoO3 nanorods were prepared by electrochemical reduction method using the tetra propyl ammonium bromide (TPAB) was structure directing agent in an organic medium viz. tetra hydro furan (THF) and acetonitrile (ACN) in 4:1 ratio and at current density 14mA &18 mA. The reduction process takes place under atmospheric condition over a period of 2 h. Dried sample was calcinated in muffle furnace at 500ºC. The parameters such as current density and concentration of stabilizers were used to control the size of nanorods. The synthesized MoO3 nanorods were characterized by using UV-Visible, FT-IR, XRD, SEM-EDS and TEM analysis techniques.
SYNTHESIS OF COPPER SILVER NANOPARTICLES BY SOLUTION COMBUSTION SYNTHESIS MET...Zuhair Bin Jawaid
1. The document describes a project to synthesize silver and copper nanoparticles using a solution combustion synthesis method. This method involves mixing metal nitrates with fuels like glycine or urea in solution, resulting in a self-sustaining exothermic reaction that produces nanopowders.
2. Key parameters that affect the combustion synthesis process and properties of the synthesized nanoparticles include the flame type, characteristic temperatures during combustion, amount of gas generated, and the fuel to oxidizer ratio. Control of these parameters allows for tuning of the particle size, morphology, and crystallinity.
3. The solution combustion synthesis method offers a single-step process for rapidly producing pure and homogeneous nanopowders for applications in areas like energy
56.Synthesis, Characterization and Antibacterial activity of iron oxide Nanop...Annadurai B
This document summarizes the synthesis, characterization, and antibacterial activity of iron oxide nanoparticles. Key points:
- Iron oxide nanoparticles were synthesized using a co-precipitation method by adding mixtures of metal salts to a sodium hydroxide solution, producing particles between 14-68 nm in size.
- Characterization using XRD, FTIR, VSM, and SEM confirmed the crystalline cubic spinel structure and magnetic properties of the nanoparticles. Particle size decreased with increased manganese substitution.
- Magnetic measurements showed saturation magnetization and coercivity decreased with increased manganese content due to changes in exchange interactions between metal sites.
- Antibacterial tests showed the nanoparticles had moderate antibacterial effects against E
The document summarizes the synthesis and characterization of chitosan/silver biopolymer nanocomposites. Chitosan/silver nanocomposite films were synthesized using ultrasonication and spin coating methods. The films were characterized using UV-Vis spectroscopy, FTIR, XRD, dielectric measurements, and four probe resistivity measurements. The characterization confirmed the presence of silver nanoparticles embedded in the chitosan polymer matrix. The dielectric constant was found to decrease with increasing frequency. Electrical measurements showed linear current-voltage behavior consistent with Ohm's law. The document concluded the synthesis and characterization techniques provided an understanding of the chitosan/silver nanocomposite materials.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Biopolymer based nanomaterials as potential biosorbents for toxic metal ionsAlexander Decker
This document summarizes a research study on the use of ternary nanoparticles composed of chitosan, yeast, and gelatin for removing toxic copper ions from water. The nanoparticles were characterized using FTIR and TEM analysis. FTIR showed the presence of functional groups from the three biopolymers and shifts upon copper ion adsorption. TEM revealed nanoparticle sizes ranging from 50-150 nm. Batch experiments showed over 90% copper ion removal, with adsorption fitting well to the Langmuir isotherm model. The effects of biopolymer composition, metal ion concentration, pH, and temperature on adsorption capacity were also examined.
Synthesis, characterization and electrocatalytic activity of silver nanorods ...kutty79
This paper describes a simple method of synthesizing silver nanorods using the polyol process, where propylene glycol serves both as a reducing
agent and as a solvent in the presence of a capping reagent such as polyvinylpyrrolidone (PVP). The diameter and length of silver nanorods could be
controlled by changing the AgNO3/PVP ratio. The end-to-end assembly of the silver nanorods was found. The silver nanorods were characterized by
using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and absorption spectroscopy. The catalytic activity of a
glassy carbon electrode with Ag nanorods exhibits extraordinary electrocatalytic activities towards the electro-reduction of benzyl chloride.
Biological and Medical Applications of Graphene NanoparticlesAI Publications
Graphene which is one of the latest additions to nanocarbon family has peculiar band structure, extraordinary thermal and electronic conductance and room temperature quantum Hall effect. It is used in for various applications in diverse fields ranging from catalysis to electronics. In addition to being components in electronic devices, GO have been used in nanocomposite materials, polymer composite materials, energy storage, biomedical applications, catalysis and as a surfactant with some overlaps between these fields Graphene oxide is a unique material that can be viewed as a single monomolecular layer of graphite with various oxygen containing functionalities such as epoxide, carbonyl, carboxyl and hydroxyl groups.
Electrochemical Synthesis of MoO3 Nanoparticles Effect of Temperature Convert...IJERA Editor
MoO3 nanorods were prepared by electrochemical reduction method using the tetra propyl ammonium bromide (TPAB) was structure directing agent in an organic medium viz. tetra hydro furan (THF) and acetonitrile (ACN) in 4:1 ratio and at current density 14mA &18 mA. The reduction process takes place under atmospheric condition over a period of 2 h. Dried sample was calcinated in muffle furnace at 500ºC. The parameters such as current density and concentration of stabilizers were used to control the size of nanorods. The synthesized MoO3 nanorods were characterized by using UV-Visible, FT-IR, XRD, SEM-EDS and TEM analysis techniques.
SYNTHESIS OF COPPER SILVER NANOPARTICLES BY SOLUTION COMBUSTION SYNTHESIS MET...Zuhair Bin Jawaid
1. The document describes a project to synthesize silver and copper nanoparticles using a solution combustion synthesis method. This method involves mixing metal nitrates with fuels like glycine or urea in solution, resulting in a self-sustaining exothermic reaction that produces nanopowders.
2. Key parameters that affect the combustion synthesis process and properties of the synthesized nanoparticles include the flame type, characteristic temperatures during combustion, amount of gas generated, and the fuel to oxidizer ratio. Control of these parameters allows for tuning of the particle size, morphology, and crystallinity.
3. The solution combustion synthesis method offers a single-step process for rapidly producing pure and homogeneous nanopowders for applications in areas like energy
56.Synthesis, Characterization and Antibacterial activity of iron oxide Nanop...Annadurai B
This document summarizes the synthesis, characterization, and antibacterial activity of iron oxide nanoparticles. Key points:
- Iron oxide nanoparticles were synthesized using a co-precipitation method by adding mixtures of metal salts to a sodium hydroxide solution, producing particles between 14-68 nm in size.
- Characterization using XRD, FTIR, VSM, and SEM confirmed the crystalline cubic spinel structure and magnetic properties of the nanoparticles. Particle size decreased with increased manganese substitution.
- Magnetic measurements showed saturation magnetization and coercivity decreased with increased manganese content due to changes in exchange interactions between metal sites.
- Antibacterial tests showed the nanoparticles had moderate antibacterial effects against E
The Effect of Size of the CuO Nanoleaves on the Sunlight Driven Photocatalyti...IRJET Journal
This document summarizes research on the effect of surfactant concentration on the size and photocatalytic properties of copper oxide nano leaves. Copper oxide nano leaves were synthesized using different concentrations of polyvinyl pyrrolidone (PVP) as a surfactant. Characterization with XRD, FTIR and SEM showed that increasing PVP concentration decreased particle size and altered morphology from narrow leaves to shortened, broadened leaves. Photocatalytic testing demonstrated that the sample with the highest PVP concentration degraded Congo Red dye in sunlight most effectively within 4 hours, indicating smaller size and higher surface area enhanced photocatalytic activity.
Since the Nobel prize for Physics was awarded to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene”, the eyes of the scientific world have been focused on this so-called miracle material.
A numerical analysis of various p h level for fiber optic ph sensor based on ...Journal Papers
This document summarizes research on the development and characterization of an optical fiber pH sensor. Key points:
- Researchers coated the core of a plastic clad silica fiber with a sol-gel film containing the pH indicator bromophenol blue. The intensity of light transmitted through the fiber was measured at different pH levels.
- Statistical analysis identified pH2 as providing the highest significance in changes in light intensity, indicating it could be used as a reference point for the sensor.
- The sensor was characterized using techniques like FESEM, UV-vis spectroscopy, and spectrophotometry to analyze its structure and optical properties. Calibration curves were generated relating light intensity to pH.
- The sensor is
Photochemistry Mediated Synthesis and Characterization of Thyroxine Capped Si...priyanka raviraj
Thyroxine capped silver nanoparticles were synthesized using a one-step photochemical method. Characterization showed the nanoparticles were spherical, ranging from 12-16 nm in size, with a surface plasmon resonance peak at 418 nm. Fourier transform infrared spectroscopy indicated the thyroxine involved amine and hydroxyl groups in reducing silver nitrate. The nanoparticles were stable for 20 days at temperatures from 4-50°C.
Wafer scale fabrication of nitrogen-doped reduced graphene oxide with enhance...Journal Papers
1) The document describes a study on wafer-scale fabrication of nitrogen-doped reduced graphene oxide (N-rGO) with enhanced quaternary-N content for high-performance photodetection.
2) Various characterization techniques were used to analyze the morphology, atomic structure, elemental composition and defects of N-rGO produced under different plasma treatment conditions. N-rGO treated at 20W for 10min showed uniform film formation with nitrogen doping and carbon deposition.
3) XPS and Raman analysis confirmed the incorporation of nitrogen into the graphene lattice, with major pyridinic-N content. This reduced defects and improved the structural and electronic properties of N-rGO compared to reduced graphene oxide
The document describes a study that deposited electrochemically reduced graphene oxide (ERGO) on aluminium copper (AlCu) substrates using electrodeposition at different voltage windows and cycles to produce humidity sensors. ERGO was deposited at voltage windows of 0.3V to -0.2V and 0.3V to -0.6V, with 1, 2, or 3 cycles within each window. Raman spectroscopy showed the deposited ERGO had characteristic D, G, and 2D bands. Humidity sensing tests found the sample deposited at 0.3V to -0.6V for 2 cycles had the highest sensitivity of 67.63% due to its thicker nanoporous structure providing a larger surface area to absorb water
Optical studies of nano structured la-doped zn o prepared by combustion methodsuresh800
This document summarizes research on the optical properties of lanthanum-doped zinc oxide (ZnO) nanostructures prepared using a combustion synthesis method. Coral-shaped ZnO nanostructures with an average grain size of 15 nm were successfully synthesized. Transmission electron microscopy showed the nanostructures were porous with pore sizes of 10-50 nm. X-ray diffraction analysis confirmed the wurtzite crystal structure of both pure and lanthanum-doped ZnO. Doping with lanthanum altered the structural and optical properties of ZnO. Ultraviolet-visible spectroscopy showed the band gap of ZnO increased with higher lanthanum concentration. Photoluminescence spectra exhibited lanthanum characteristic emission and a
Crimson publishers-Biosynthesis of the Fe3O4 Nanoparticles Using Acacia Nilot...CrimsonpublishersTTEFT
Biosynthesis of the Fe3O4 Nanoparticles Using Acacia Nilotica Leaf Extract and their Effect on Degradation of Congo Red Dye in Aqueous Solution by Vasantha Jyothi NVV* and Venkateswarlu P* in Trends in Textile Engineering & Fashion Technology
Graphene oxide is synthesized by treating graphite with strong oxidizing agents like potassium chlorate, potassium permanganate, and acids. It has a layered structure with oxygen-containing functional groups such as hydroxyl and epoxy groups bonded to the basal graphene planes. These functional groups make graphene oxide hydrophilic and soluble in water. Graphene oxide can be chemically reduced by removing oxygen groups or chemically functionalized by reacting functional groups on the basal planes with other molecules through covalent bonding.
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
Fabrication and characterization of conducting polymer compositeijoejournal
The document summarizes research on fabricating and characterizing a conducting polymer composite of polyvinylpyrrolidone (PVP) and potassium hydroxide (KOH). Specifically:
1. PVP and KOH were mixed using a solution casting method to prepare polymer composite specimens.
2. Tests found that the composite's conductivity and microhardness increased with higher KOH concentrations. The highest conductivity was 4×10-4 S/cm at 35 wt% KOH.
3. Microstructure analysis using an optical microscope showed even KOH distribution throughout the composite at 35 wt% KOH, the concentration with highest conductivity.
Investigation on the structure, electrical conductivity and ethanol gas sensi...saad yakout
The document discusses the investigation of Ce-doped tin oxide (SnO2) nanoparticles for use as ethanol gas sensors. SnO2 nanoparticles were synthesized by chemical precipitation and doped with 0-6 wt% cerium dioxide (CeO2). The nanoparticles were characterized using various techniques. XRD and IR analysis confirmed the formation of tetragonal rutile SnO2 and cubic CeO2 structures. SEM and TEM showed the particle size of SnO2 increased with sintering temperature but decreased with CeO2 additions. Electrical conductivity increased with temperature and CeO2 content. Gas sensing tests found the 2 wt% CeO2 sample sintered at 400°C had the highest sensitivity, fastest response
Surface modification and properties modulation of r go film by short duration...Journal Papers
This document discusses the effects of hydrogen (H2) plasma and ammonia (NH3) plasma treatments on the surface and properties of reduced graphene oxide (rGO) films. Low-power H2 plasma at low and medium temperatures further reduced oxygen content in the rGO films but slightly reduced conductivity. Low-power H2 plasma at high temperature introduced defects that significantly reduced conductivity. Medium-power NH3 plasma did not effectively dope the rGO with nitrogen but did reduce conductivity through etching. Higher-power NH3 plasma treatments doped the rGO with nitrogen but also significantly etched the films, greatly reducing hole concentration and conductivity. The highest-power NH3 plasma treatment produced an electron-dominated film with the lowest
This document examines the effect of synthesis conditions on the growth of ZnO nanorods via a hydrothermal method. It finds that the morphology and ordering of ZnO nanorods are determined by growth temperature, the overall concentration of precursors, and deposition time. ZnO nanorod morphology and surface-to-volume ratio are most sensitive to temperature. The width of ZnO nanorods can be controlled by the overall concentration of reactants and temperature. Different temperatures resulted in nanorods of varying diameters and lengths, demonstrating the influence of chemical reactions, nucleation, and growth processes on nanorod morphology.
The document describes the synthesis of magnetic cryptomelane-type manganese oxide nanotubes for removing lead compounds from water samples. It involves depositing iron(II) oxide nanoparticles onto manganese oxide nanotubes via a hydrothermal and precipitation method. Characterization shows the composite exhibits excellent magnetic properties and removes over 98% of lead from 0.1M and 0.05M lead acetate solutions, leaving clear water behind. The material could have applications in water purification due to its simple manipulation and high adsorption activity for heavy metal degradation.
Diffusion Dynamics of Metal Ions Uptake at the CarboxylatedEpichlorohydrin Re...IJERA Editor
Investigation into the diffusion dynamics of Mn2+ , Fe2+ and Pb2+ ions uptake from aqueous solution by chemically modified red onion skin extract was carried out. The polyhydroxylic extract of red onion skin was utilized in the synthesis of carboxylated-epichlorohydrin red onion skin extract resin (CERR). The fourier transform infrared spectra of red onion skin extract and CERR exhibited variations in bond interactions which was ascribed to the structural modification of the extract to yield CERR. Predictions of the mechanism of diffusion dynamics were carried out by applying the data resolved from the fractional attainment of equilibrium at varied times into the Vermeulen diffusion models within the temperature range of 29 to 70°C. The predominance of film diffusion mechanism was established from the smaller values of its diffusion coefficients as compared to those of particle diffusion. The film diffusion coefficient values were lowest at 29°C, indicating the most probable temperature condition for optimum exchange result with the CERR. Deductions from utilizing the Arrhenius type temperature dependence equation gave negative values of activation energy (-7.223 kJ/mol for Mn2+ , -6.898 kJ/mol for Fe2+ and -13.957 kJ/mol for Pb2+ ions); which suggests that increase in temperature from 29 to 70°C, lowered the rate of the exchange reaction.
Synthesis and Characterization of Silver Nanoparticle and Liquid Crystal Nano...Mohammad Azam
This document summarizes Mohammad Azam's thesis on synthesizing silver nanoparticles and incorporating them into liquid crystal nanocomposites. It outlines the synthesis of silver nanoparticles using a chemical reduction method with sodium borohydride and characterization using UV-Vis spectroscopy. It also discusses future work on studying the effects of adding the silver nanoparticles to a discotic liquid crystal and analyzing the optical, thermal, and electrical properties of the nanocomposite using spectroscopy and differential scanning calorimetry. The document concludes that the size and band gap of the silver nanoparticles can be tuned and adding them may decrease the band gap and increase conductivity of the liquid crystal.
Crash Analysis of Front under Run Protection Device using Finite Element Anal...IOSR Journals
Under-running of passenger vehicles is one of the important parameters to be considered during
design and development of truck chassis. Front Under-run Protection Device (FUPD) plays an important role
in avoiding under-running of vehicles from front side of a truck. An explicit finite element software Altair
Radio's is used in FUPD analysis for impact loading. The deformation of FUPD bar and plastic strains in
FUPD components are determined in the impact analysis for predicting failure of the system to meet the
compliance requirements as per IS 14812-2005. Additionally, failure analysis of the FUPD attachment points
with chassis is determined. Physical testing can be reduced significantly with this approach which ultimately
reduces the total cycle time as well as the cost involved in product development.
Evaluation Of Analgesic And Anti Inflammatory Activity Of Siddha Drug Karuvil...IOSR Journals
The document evaluates the analgesic and anti-inflammatory activities of Karuvilanchi ver chooranam (KVC), the root powder of Smilax zeylanica, in rodent models. The results showed that KVC significantly increased the reaction time in hot plate test and reduced acetic acid-induced writhing, indicating analgesic effects. KVC also significantly reduced formalin-induced paw edema and cotton pellet-induced granuloma formation, demonstrating anti-inflammatory properties. The effects were found to be dose-dependent. The study confirms the traditional use of KVC in managing pain and inflammation.
IOSR Journal of Business and Management (IOSR-JBM) is an open access international journal that provides rapid publication (within a month) of articles in all areas of business and managemant and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications inbusiness and management. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
The Effect of Size of the CuO Nanoleaves on the Sunlight Driven Photocatalyti...IRJET Journal
This document summarizes research on the effect of surfactant concentration on the size and photocatalytic properties of copper oxide nano leaves. Copper oxide nano leaves were synthesized using different concentrations of polyvinyl pyrrolidone (PVP) as a surfactant. Characterization with XRD, FTIR and SEM showed that increasing PVP concentration decreased particle size and altered morphology from narrow leaves to shortened, broadened leaves. Photocatalytic testing demonstrated that the sample with the highest PVP concentration degraded Congo Red dye in sunlight most effectively within 4 hours, indicating smaller size and higher surface area enhanced photocatalytic activity.
Since the Nobel prize for Physics was awarded to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene”, the eyes of the scientific world have been focused on this so-called miracle material.
A numerical analysis of various p h level for fiber optic ph sensor based on ...Journal Papers
This document summarizes research on the development and characterization of an optical fiber pH sensor. Key points:
- Researchers coated the core of a plastic clad silica fiber with a sol-gel film containing the pH indicator bromophenol blue. The intensity of light transmitted through the fiber was measured at different pH levels.
- Statistical analysis identified pH2 as providing the highest significance in changes in light intensity, indicating it could be used as a reference point for the sensor.
- The sensor was characterized using techniques like FESEM, UV-vis spectroscopy, and spectrophotometry to analyze its structure and optical properties. Calibration curves were generated relating light intensity to pH.
- The sensor is
Photochemistry Mediated Synthesis and Characterization of Thyroxine Capped Si...priyanka raviraj
Thyroxine capped silver nanoparticles were synthesized using a one-step photochemical method. Characterization showed the nanoparticles were spherical, ranging from 12-16 nm in size, with a surface plasmon resonance peak at 418 nm. Fourier transform infrared spectroscopy indicated the thyroxine involved amine and hydroxyl groups in reducing silver nitrate. The nanoparticles were stable for 20 days at temperatures from 4-50°C.
Wafer scale fabrication of nitrogen-doped reduced graphene oxide with enhance...Journal Papers
1) The document describes a study on wafer-scale fabrication of nitrogen-doped reduced graphene oxide (N-rGO) with enhanced quaternary-N content for high-performance photodetection.
2) Various characterization techniques were used to analyze the morphology, atomic structure, elemental composition and defects of N-rGO produced under different plasma treatment conditions. N-rGO treated at 20W for 10min showed uniform film formation with nitrogen doping and carbon deposition.
3) XPS and Raman analysis confirmed the incorporation of nitrogen into the graphene lattice, with major pyridinic-N content. This reduced defects and improved the structural and electronic properties of N-rGO compared to reduced graphene oxide
The document describes a study that deposited electrochemically reduced graphene oxide (ERGO) on aluminium copper (AlCu) substrates using electrodeposition at different voltage windows and cycles to produce humidity sensors. ERGO was deposited at voltage windows of 0.3V to -0.2V and 0.3V to -0.6V, with 1, 2, or 3 cycles within each window. Raman spectroscopy showed the deposited ERGO had characteristic D, G, and 2D bands. Humidity sensing tests found the sample deposited at 0.3V to -0.6V for 2 cycles had the highest sensitivity of 67.63% due to its thicker nanoporous structure providing a larger surface area to absorb water
Optical studies of nano structured la-doped zn o prepared by combustion methodsuresh800
This document summarizes research on the optical properties of lanthanum-doped zinc oxide (ZnO) nanostructures prepared using a combustion synthesis method. Coral-shaped ZnO nanostructures with an average grain size of 15 nm were successfully synthesized. Transmission electron microscopy showed the nanostructures were porous with pore sizes of 10-50 nm. X-ray diffraction analysis confirmed the wurtzite crystal structure of both pure and lanthanum-doped ZnO. Doping with lanthanum altered the structural and optical properties of ZnO. Ultraviolet-visible spectroscopy showed the band gap of ZnO increased with higher lanthanum concentration. Photoluminescence spectra exhibited lanthanum characteristic emission and a
Crimson publishers-Biosynthesis of the Fe3O4 Nanoparticles Using Acacia Nilot...CrimsonpublishersTTEFT
Biosynthesis of the Fe3O4 Nanoparticles Using Acacia Nilotica Leaf Extract and their Effect on Degradation of Congo Red Dye in Aqueous Solution by Vasantha Jyothi NVV* and Venkateswarlu P* in Trends in Textile Engineering & Fashion Technology
Graphene oxide is synthesized by treating graphite with strong oxidizing agents like potassium chlorate, potassium permanganate, and acids. It has a layered structure with oxygen-containing functional groups such as hydroxyl and epoxy groups bonded to the basal graphene planes. These functional groups make graphene oxide hydrophilic and soluble in water. Graphene oxide can be chemically reduced by removing oxygen groups or chemically functionalized by reacting functional groups on the basal planes with other molecules through covalent bonding.
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
Fabrication and characterization of conducting polymer compositeijoejournal
The document summarizes research on fabricating and characterizing a conducting polymer composite of polyvinylpyrrolidone (PVP) and potassium hydroxide (KOH). Specifically:
1. PVP and KOH were mixed using a solution casting method to prepare polymer composite specimens.
2. Tests found that the composite's conductivity and microhardness increased with higher KOH concentrations. The highest conductivity was 4×10-4 S/cm at 35 wt% KOH.
3. Microstructure analysis using an optical microscope showed even KOH distribution throughout the composite at 35 wt% KOH, the concentration with highest conductivity.
Investigation on the structure, electrical conductivity and ethanol gas sensi...saad yakout
The document discusses the investigation of Ce-doped tin oxide (SnO2) nanoparticles for use as ethanol gas sensors. SnO2 nanoparticles were synthesized by chemical precipitation and doped with 0-6 wt% cerium dioxide (CeO2). The nanoparticles were characterized using various techniques. XRD and IR analysis confirmed the formation of tetragonal rutile SnO2 and cubic CeO2 structures. SEM and TEM showed the particle size of SnO2 increased with sintering temperature but decreased with CeO2 additions. Electrical conductivity increased with temperature and CeO2 content. Gas sensing tests found the 2 wt% CeO2 sample sintered at 400°C had the highest sensitivity, fastest response
Surface modification and properties modulation of r go film by short duration...Journal Papers
This document discusses the effects of hydrogen (H2) plasma and ammonia (NH3) plasma treatments on the surface and properties of reduced graphene oxide (rGO) films. Low-power H2 plasma at low and medium temperatures further reduced oxygen content in the rGO films but slightly reduced conductivity. Low-power H2 plasma at high temperature introduced defects that significantly reduced conductivity. Medium-power NH3 plasma did not effectively dope the rGO with nitrogen but did reduce conductivity through etching. Higher-power NH3 plasma treatments doped the rGO with nitrogen but also significantly etched the films, greatly reducing hole concentration and conductivity. The highest-power NH3 plasma treatment produced an electron-dominated film with the lowest
This document examines the effect of synthesis conditions on the growth of ZnO nanorods via a hydrothermal method. It finds that the morphology and ordering of ZnO nanorods are determined by growth temperature, the overall concentration of precursors, and deposition time. ZnO nanorod morphology and surface-to-volume ratio are most sensitive to temperature. The width of ZnO nanorods can be controlled by the overall concentration of reactants and temperature. Different temperatures resulted in nanorods of varying diameters and lengths, demonstrating the influence of chemical reactions, nucleation, and growth processes on nanorod morphology.
The document describes the synthesis of magnetic cryptomelane-type manganese oxide nanotubes for removing lead compounds from water samples. It involves depositing iron(II) oxide nanoparticles onto manganese oxide nanotubes via a hydrothermal and precipitation method. Characterization shows the composite exhibits excellent magnetic properties and removes over 98% of lead from 0.1M and 0.05M lead acetate solutions, leaving clear water behind. The material could have applications in water purification due to its simple manipulation and high adsorption activity for heavy metal degradation.
Diffusion Dynamics of Metal Ions Uptake at the CarboxylatedEpichlorohydrin Re...IJERA Editor
Investigation into the diffusion dynamics of Mn2+ , Fe2+ and Pb2+ ions uptake from aqueous solution by chemically modified red onion skin extract was carried out. The polyhydroxylic extract of red onion skin was utilized in the synthesis of carboxylated-epichlorohydrin red onion skin extract resin (CERR). The fourier transform infrared spectra of red onion skin extract and CERR exhibited variations in bond interactions which was ascribed to the structural modification of the extract to yield CERR. Predictions of the mechanism of diffusion dynamics were carried out by applying the data resolved from the fractional attainment of equilibrium at varied times into the Vermeulen diffusion models within the temperature range of 29 to 70°C. The predominance of film diffusion mechanism was established from the smaller values of its diffusion coefficients as compared to those of particle diffusion. The film diffusion coefficient values were lowest at 29°C, indicating the most probable temperature condition for optimum exchange result with the CERR. Deductions from utilizing the Arrhenius type temperature dependence equation gave negative values of activation energy (-7.223 kJ/mol for Mn2+ , -6.898 kJ/mol for Fe2+ and -13.957 kJ/mol for Pb2+ ions); which suggests that increase in temperature from 29 to 70°C, lowered the rate of the exchange reaction.
Synthesis and Characterization of Silver Nanoparticle and Liquid Crystal Nano...Mohammad Azam
This document summarizes Mohammad Azam's thesis on synthesizing silver nanoparticles and incorporating them into liquid crystal nanocomposites. It outlines the synthesis of silver nanoparticles using a chemical reduction method with sodium borohydride and characterization using UV-Vis spectroscopy. It also discusses future work on studying the effects of adding the silver nanoparticles to a discotic liquid crystal and analyzing the optical, thermal, and electrical properties of the nanocomposite using spectroscopy and differential scanning calorimetry. The document concludes that the size and band gap of the silver nanoparticles can be tuned and adding them may decrease the band gap and increase conductivity of the liquid crystal.
Crash Analysis of Front under Run Protection Device using Finite Element Anal...IOSR Journals
Under-running of passenger vehicles is one of the important parameters to be considered during
design and development of truck chassis. Front Under-run Protection Device (FUPD) plays an important role
in avoiding under-running of vehicles from front side of a truck. An explicit finite element software Altair
Radio's is used in FUPD analysis for impact loading. The deformation of FUPD bar and plastic strains in
FUPD components are determined in the impact analysis for predicting failure of the system to meet the
compliance requirements as per IS 14812-2005. Additionally, failure analysis of the FUPD attachment points
with chassis is determined. Physical testing can be reduced significantly with this approach which ultimately
reduces the total cycle time as well as the cost involved in product development.
Evaluation Of Analgesic And Anti Inflammatory Activity Of Siddha Drug Karuvil...IOSR Journals
The document evaluates the analgesic and anti-inflammatory activities of Karuvilanchi ver chooranam (KVC), the root powder of Smilax zeylanica, in rodent models. The results showed that KVC significantly increased the reaction time in hot plate test and reduced acetic acid-induced writhing, indicating analgesic effects. KVC also significantly reduced formalin-induced paw edema and cotton pellet-induced granuloma formation, demonstrating anti-inflammatory properties. The effects were found to be dose-dependent. The study confirms the traditional use of KVC in managing pain and inflammation.
IOSR Journal of Business and Management (IOSR-JBM) is an open access international journal that provides rapid publication (within a month) of articles in all areas of business and managemant and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications inbusiness and management. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
IOSR Journal of Business and Management (IOSR-JBM) is an open access international journal that provides rapid publication (within a month) of articles in all areas of business and managemant and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications inbusiness and management. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Prevalence of Cleft Lip and Palate in Abuja Nigeria (From December2000 to Dec...IOSR Journals
The prevalence of cleft lip and palate in University of Abuja Teaching Hospital from December 2000 to December 2010 was investigated in this works and was found to be 3.2 in every 1,000 live birth. This is very high as compared to reports from earlier works but was suspected to be due to the smile Train Project which is a private sector driven initiative that takes up the burden of paying for cleft lip and palate repair. Left sides clefts of the lip and palate were found to be almost twice that of right sides cleft of the lip and palate. This was in keeping with reports from earlier works. This study shows there is need for further studies in the field of cleft lip palate in all regions of the country
This study examined the correlation between central corneal thickness (CCT) and results from Frequency Doubling Technology Perimetry (FDT) in 180 patients aged 40 or older with high intraocular pressure (IOP) but normal optic discs. The average CCT across both eyes was 531 microns. Abnormal FDT results were found in 18 subjects, who had thinner average CCT of 519 microns, compared to 532 microns in 162 subjects with normal FDT results. The study concludes that among patients with high IOP but normal discs, thicker corneas are associated with a lower risk of early glaucomatous damage detected by FDT, compared to patients with thinner corneas.
The Production of Triploid Clariobranchus in Indoor HatcheryIOSR Journals
This study evaluated the interactive effects of rhizobium and virus inocula on three cowpea cultivars. The cultivars were inoculated with two rhizobium strains (R25B and IRj2180A) and two virus strains (CABMV and CYMV) at two different times. Viral inoculation significantly reduced nodulation, biomass production, and grain yields across all cultivars. Maximum reductions occurred without rhizobium inoculation. Early inoculation had a greater effect than late inoculation. The interaction of rhizobium and virus strains showed that viral severity was not reduced by rhizobium presence. Cultivar IT90K-277-2 performed best
Correlation Coefficient Based Average Textual Similarity Model for Informatio...IOSR Journals
The document presents a proposed model for a textual similarity approach for information retrieval systems in wide area networks. It evaluates the performance of four similarity functions (Jaccard, Cosine, Dice, Overlap) using correlation coefficients. Three approaches are proposed: 1) Combining Cosine and Overlap similarity scores, which performed best. 2) Combining Cosine, Dice, and Overlap scores. 3) Combining all four similarity functions. The model is represented as a triangle where the vertices are the results from the three proposed approaches to measure textual similarity between retrieved documents.
The study of semiconductor layer effect on underground cables with Time Domai...IOSR Journals
This document presents a study on how the semiconductor layers in underground cables can affect Time Domain Reflectometry (TDR) measurements. The researchers developed a circuit model that includes the electrical resistance of the semiconductor layers to better simulate TDR signals. Simulations using the proposed model showed good agreement with measurements from a new cable but not an aged cable. The model was updated to represent resistance in the aged cable's semiconductor layers caused by degradation over time. Simulations with this updated model matched experimental TDR results from the aged cable better than the original model. The study demonstrates that changes in semiconductor layer resistance due to aging can impact TDR pulse propagation in cables.
The Phase Theory towards the Unification of the Forces of Nature the Heart Be...IOSR Journals
A new theory has been presented, for the first time, called the "Phase Theory", which is the natural evolution of the physical thought and is considered the one beyond the super string theory. This theory solves the unsolved problems of the mysterious of matter, antimatter and interactions and makes a wide step towards the unification of the forces of nature. In this theory, the vibrating string of different frequency modes which determines the different types of elementary particles is replaced by a three dimensional infinitesimal pulsating (black)holes with the same frequency. Different types of elementary particles are determined by different phase angles associated with the same frequency. This allows the force of interactions to take place among elementary particles, without the need to invoke the notion of the force carrier particles, as the (stable) force of interactions can never take place between elementary particles at different frequencies. Besides the strong mathematical proofs given in this paper to prove its truthfulness, an experimental prediction has been given to confirm the theory presented in the form of the relation between the electron radius and quarks radii. The paper shows that quarks are direct consequence of this theory, and solves "the flavor problem" in QCD, and gives the clue to answer the questions of "Why are there so many flavors? The paper also derives the equation of the big bang theory which describes the singularity of the moment of creation of the universe.
Abstract: We present a new algorithm, called the soft-tissue filter that can make both soft and bone tissue clearly visible in digital cephalic radiographies under a wide range of exposures. It uses a mixture model made up of two Gaussian distributions and one inverted lognormal distribution to analyze the image histogram. The image is clustered in three parts: background, soft tissue, and bone using this model. Improvement in the visibility of both structures is achieved through a local transformation based on gamma correction, stretching, and saturation, which is applied using different parameters for bone and soft-tissue pixels. A processing time of 1 s for 5 M pixel images allows the filter to operate in real time. Although the default value of the filter parameters is adequate for most images, real-time operation allows adjustment to recover under- and overexposed images or to obtain the best quality subjectively. The filter was extensively clinically tested: quantitative and qualitative results are reported here Index Terms: Digital radiography, histogram-based clustering, image enhancement, local gamma correction
Outlining Bangla Word Dictionary for Universal Networking LanguageIOSR Journals
This document discusses outlining a Bangla word dictionary for the Universal Networking Language (UNL) system. UNL is an artificial language that allows computers to process information across languages. The authors have been working to include Bangla in the UNL system. They describe the format of a UNL dictionary entry, which includes the headword (Bangla word), universal word, and grammatical attributes. Simply searching the UNL knowledge base for universal words is not effective, so they propose finding universal words based on existing translations of Bangla texts to English and their UNL expressions. The goal is to develop a Bangla dictionary to facilitate converting Bangla sentences to UNL format.
An Efficient Algorithm for the Segmentation of Astronomical ImagesIOSR Journals
This document proposes an efficient algorithm for segmenting celestial objects from astronomical images. The algorithm uses multiple preprocessing steps including removing bright point sources, stationary wavelet transform, total variation denoising, and adaptive histogram equalization. Level set segmentation is then used as the key technique for segmentation. Preprocessing helps overcome issues like noise, weak object edges, and low contrast. Level set segmentation can segment objects while retaining their texture and shape information for subsequent classification. The algorithm is tested on various celestial objects and shown to effectively segment them.
Data Security Model Enhancement In Cloud EnvironmentIOSR Journals
This document discusses enhancing data security in cloud environments. It begins by providing background on cloud computing, including its key characteristics and architecture. The document then discusses existing security concerns with cloud computing, as sensitive user data is stored remotely by cloud providers. The main objective is to propose an enhanced data security model for clouds. The proposed model uses a three-layer architecture and efficient algorithms to ensure security at each layer and solve common cloud data security issues like authentication, data protection, and fast data recovery.
Gain Comparison between NIFTY and Selected Stocks identified by SOM using Tec...IOSR Journals
This document discusses a study that uses self-organizing maps (SOM) and technical indicators to identify stocks with potential for investment gains. The study selects stocks and compares their returns over 1.5 months to the NIFTY index. The stocks identified using SOM and technical indicators performed 37.14% better than the NIFTY index over that period. The document provides background on technical analysis indicators like RSI, MACD, and OBV that were used in the analysis. It also describes how SOM can be used to classify stocks based on technical indicator values and select stocks that closely match the properties of the best performing class.
This document summarizes a research paper that proposes using a genetic algorithm to optimize the placement of Fiber Bragg Grating sensors for structural health monitoring. It begins by introducing FBG sensors and the need for sensor placement optimization when resources are limited. It then provides background on genetic algorithms and describes how they can be applied to the sensor placement problem by coding sensor locations into chromosomes, evaluating fitness, and using genetic operators like selection, crossover and mutation to evolve optimized sensor configurations. The document explains the genetic algorithm approach in detail through sections on coding, initial population, selection, crossover and mutation operations.
A study to Design and comparison of Full Adder using Various TechniquesIOSR Journals
Abstract: Adders is widely used in applications such as digital signal processing (DSP) and microprocessors. In this paper Half adders are simulated and analyzed based on power dissipation, area and speed on 90nm technology using Microwind and Dsch tool. Half Adder is the basic building block in Parallel Feedback Carry Adder (PFCA). Keywords: Full adder, Half adder, PFCA, VLSI
Bayesian Estimation of Above-Average Performance in Tertiary Institutions: A ...IOSR Journals
Bayesian approach for parameter estimation has the capacity to yield more precise estimates than methods based on sampling theory. There are several common Bayesian models; in this study we applied Empirical Bayes (EB) model called Beta-binomial model. The study is motivated by the need to beam searchlight on universities, faculties or fields of study with graduates who may not be eligible for further educational pursuits. This study provides means of assessment or a basis of evaluation of students’ performances among faculties or fields of study and overall performance of a university. This study uses Bayesian methods of inference to estimate the proportion of above-average performance of graduates from the various faculties in University of Lagos. The model adopted generated results which are of smaller variances compared with variances of sample Proportions, showing that the posterior proportions generated are more efficient estimators. This is further evidenced in narrow widths of the computed confidence intervals. The overall result shows that the proportion of above-average performance of graduates of University of Lagos, who are eligible for further educational pursuits (i.e. higher degrees), is approximately 72% of the university graduates
The effect of rotational speed variation on the static pressure in the centri...IOSR Journals
1) A numerical simulation was conducted to examine the effect of rotational speed variation on static pressure in a centrifugal pump.
2) Contours of static pressure on the blade, hub, and shroud were generated at rotational speeds of 1800 rpm to 2400 rpm.
3) The results show that static pressure is lowest on the suction side and increases towards the leading edge of the blade. Negative static pressure occurs at high rotational speeds over design limits, risking cavitation.
This document presents Backlund's theorem for spacelike surfaces in Minkowski 3-space. It shows that there is a correspondence between solutions of the Sine-Gordon equation and surfaces of constant positive Gaussian curvature. Specifically, it proves that if there is a spacelike line congruence between two spacelike focal surfaces, and the distance between corresponding points and angle between normals are constant, then both surfaces have constant positive Gaussian curvature. It also establishes that the angles between the asymptotic directions of the surfaces satisfy the Sine-Gordon equation and are related by a Backlund transformation. This allows constructing a family of spacelike surfaces with the same Gaussian curvature from a given surface by solving the S
Hierarchical fe , cu- and co-beta zeolites obtained by mesotemplate free meth...seranim22
This document describes the synthesis and catalytic testing of hierarchical Fe-, Cu-, and Co-beta zeolites for N2O decomposition. Two series of beta zeolites were prepared - a conventional microporous beta zeolite (Beta) and a micro-mesoporous beta zeolite (Beta/meso) prepared using a mesotemplate-free method. Both series were ion exchanged with Fe, Cu, and Co and tested as catalysts for N2O decomposition under various conditions. The Cu-Beta catalyst showed the highest activity for N2O decomposition in inert gas, while the Cu-Beta/meso catalyst had the highest reaction rate under conditions similar to nitric acid plant waste gases.
Characterization of Structural and Surface Properties of Nanocrystalline TiO2...Shingo Watanabe (渡邊真悟)
This document characterizes the structural and surface properties of TiO2-CeO2 mixed oxides synthesized using a urea coprecipitation method. Key findings include:
1) The mixed oxides have unimodal nanoporous structures with pore sizes ranging from 3.7 to 5.3 nm and higher surface areas than single TiO2 and CeO2 oxides.
2) XRD and XPS analysis show the mixed oxides have nanocrystalline structures between 4.0-5.4 nm, with distorted lattice structures indicating reduction of Ti4+ and Ce4+ ions at the surface.
3) H2-TPR and NH3-TPD reveal the mixed oxides
A facile method to prepare CdO-Mn3O4 nanocompositeIOSR Journals
CdO-Mn3O4 nanocomposite has been prepared by a simple solvothermal method using a domestic microwave oven. Cadmium acetate, manganese acetate and urea were used as the precursors and ethylene glycol as the solvent. The as-prepared sample was annealed for 1 hour in each case at different temperatures, viz. 100, 200 and 300°C. The as-prepared and annealed samples were characterized by X-ray diffraction and scanning electron microscopic analyses. Results indicate that annealing at 300°C is required to get the sample with high phase purity and homogeneity. The present study indicates that the method adopted can be considered as an economical and scalable one to prepare the proposed nanocomposite with reduced size, phase purity and homogeneity.
Development of Ni-doped Yttria stabilized Zirconia composite for SOFC applica...IOSRJAP
Ni-doped Yttria stabilized Zirconia (NiO/YSZ) has been synthesized using low cost combustion process from an aqueous solution containing ZrO(NO3)2.6H2O, Y(NO3)3.6H2O, Ni(NO3)2.6H2O and urea. Pellets were sintered at 13500C for 5 hours and its sintered density is estimated to be of 95%. Sintered pellets were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) & X-ray photoelectron spectroscopy (XPS) techniques. From the XRD analysis, as grown powder of NiO/YSZ showed nano-crystalline behavior with homogeneous mixture of YSZ and NiO phases. However sintered powder showed µ-size dense grain growth. Temperature and frequency dependent dielectric properties are corroborated with the conduction mechanism. Both dielectric constant (K) and loss (tan δ) are increased sharply at high temperature region, which is expected to be the onset of dipolar relaxation phenomena due to the presence of oxygen vacancies. A mixed conductivity involving ionic conduction in the high temperature range and electronic conduction in the low temperature range was observed. The decrease in K and tan δ with increase in frequency at a given temperature suggests the dynamic interaction of oxygen vacancies & oxide ion pairs.
The document summarizes a study on the variation in melting point of encapsulated silver nanoparticles with size. Silver nanoparticles were synthesized with inert oxide shells like ZrO2 and SiO2 using chemical methods. Characterization techniques like XRD, SEM, TEM and EDS were used to analyze the structure and composition. Differential thermal and scanning calorimetry were employed to determine the melting transition at different sizes. Samples with silver core sizes of around 12nm and 30nm were prepared using a ZrO2 shell, while SiO2 shell samples were synthesized by varying reaction parameters to obtain silver cores between 2nm to 30nm.
The document discusses copper-doped ZnO nanoparticles prepared by precipitation method with varying copper contents. Characterization techniques including XRD, XPS, EPR, TG-DTA and BET were used. XRD showed the crystallite sizes were 45-49 nm. XPS showed copper ions exist as isolated Cu2+ on the particle surfaces. EPR confirmed isolated Cu2+ ions. Photocatalytic testing showed degradation of Reactive Black 5 dye under UV light. Pure ZnO showed the best photocatalytic activity among the samples.
final accept-Optical and structural properties of TiO2 nanopowders with Co-Ce...nasrollah najibi ilkhchy
This document discusses a study on the optical and structural properties of TiO2 nanopowders doped with 2 mol% cerium and 4 mol% cobalt. X-ray diffraction analysis showed that cerium doping inhibited the formation of the rutile phase of titanium dioxide and promoted retention of the anatase phase at higher calcination temperatures. Optical absorption spectroscopy indicated that doping reduced the band gap of titanium dioxide from 3.21 eV to 3.14-3.20 eV. The crystallite size decreased with doping while the surface area increased compared to undoped titanium dioxide.
Application of Fe3O4 Sphere Doped with Zn for Enhanced Sonocatalytic Removal ...ijtsrd
The document describes research on using Fe3O4 spheres doped with zinc (Zn) as a sonocatalyst for removing hexavalent chromium (Cr(VI)) from aqueous solutions. Fe3O4 spheres doped with Zn were synthesized using a simple solvothermal method. Characterization showed the Zn was successfully doped into the crystal structure of Fe3O4 spheres. Testing found the doped spheres had high sonocatalytic activity for degrading Cr(VI) under visible light, with 95.8% removal efficiency. The enhanced activity is attributed to the uniform sphere structure and metal doping effect.
This document summarizes a study on the use of copper(I) oxide (Cu2O) nanoparticles to catalyze carbon-carbon (C-C) coupling reactions for the synthesis of polyphenylenediethynylenes. The study finds that under the reaction conditions, the Cu2O nanoparticles undergo substrate-induced leaching, forming homogeneous copper catalytic species in solution. This is evidenced by various characterization techniques and confirmed through a reactor study. The results show that the C-C coupling reactions proceed through both a heterogeneous pathway on the nanoparticle surface and a homogeneous pathway involving the leached copper species.
Preparation, Structure, and Characterization of Nd2mo2o9 fast Oxide Ion Condu...IJARIIT
The structure and ion conductivity of Nd2Mo2O9powders were synthesized by using Nd(NO2)3, MoO3, and aspartic acid (fuel) in assisted combustion method with heating at 550˚C for 6 hours. The thermal decomposition, phase identification, morphology, ionic conductivity of the samples were studied by TGA/DTA, XRD and SEM four probe D.C. method respectively. The formation of Nd2Mo2O9 was confirmed by FTIR studies. The synthesis and crystallization were followed by thermochemical techniques (TGA/DTA) studies. The synthesized materials showed reasonable ionic conductivity. These results indicate that assisted combustion method is a promising method to prepare nanocrystalline Nd2Mo2O9 for solid oxide fuel cell.
The document summarizes the preparation and characterization of mesoporous nanocrystalline zirconia with high surface area using a surfactant-assisted route. Nickel catalysts supported on the synthesized zirconia were then evaluated for dry reforming of methane to produce synthesis gas. The 5% Ni/ZrO2 catalyst exhibited stable activity for syngas production with only a 4% decrease in methane conversion after 50 hours of reaction. The addition of cerium oxide to the nickel catalyst further improved stability and decreased coke deposition.
Preparation and Structural Properties of Aluminium Substituted Lithium Nano F...IOSR Journals
This document describes the preparation and structural properties of aluminum-substituted lithium nanoferrites synthesized using the citrate gel auto combustion method. Nanoferrites with the general formula Li0.5AlxFe2.5-xO4 (where x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared at low temperature (1800C). X-ray diffraction analysis confirmed the formation of a single-phase cubic spinel structure with particle sizes ranging from 13 to 27 nm. Lattice parameter, density, and porosity were calculated from the XRD data and showed decreases with increasing aluminum content. Scanning electron microscopy revealed the formation of
Deactivation Modeling through Separable Kinetics of Coking On Ni/CZ Catalyst ...IOSR Journals
Abstract : Steam methane reforming (SMR) is a very significant technique to produce hydrogen from fossil fuels. In this particular work, nickel is used as the active metal and ceria-zirconia (CZ) bi-metallic oxide is used as the support. The foremost challenge to this process is sooting or coking over the catalyst surface and blocking the active sites. For the economic viability of the catalyst, it is very significant to make it coke deposition resistant. This is the reason that the kinetic modeling of the deactivation is very important. Therefore, this paper is aimed to model the deactivation and activity of the catalyst. A rate model of the deactivation process is also developed using separable kinetics. A comparison with commercial catalyst is also reported to show that the Ni/CZ catalyst is much more stable towards the coking. Keywords –Coking, Deactivation, Methane, Separable kinetics, Steam reforming.
A Simple Thermal Treatment Synthesis and Characterization of Ni-Zn Ferrite (N...IOSR Journals
Cubic structured nickel-zinc ferrite nanoparticles (Ni0.5Zn0.5Fe2O4) have been synthesized by thermal treatment method. This simple procedure employed an aqueous solution containing only metal nitrates as precursors, polyvinyl pyrrolidone as a capping agent, and deionized water as a solvent. The solution was thoroughly stirred for 2 hour, dried at 353 K for 3 hour, the dried material crushed into powder and calcined the powder at 873 K to remove organic substances and crystallize the particles. The microstructure properties of the prepared ferrite nanoparticles were measured using FTIR, XRD, TEM, and EDX and the magnetic properties were determined using VSM and EPR. The average particle size increased from 7 to 22 nm with the increase of calcination temperature from 723 to 873 K. The saturation magnetization, coercivity field, and g-factor increased respectively from 24 emu/g, 11 G, and 2.0673at 723 K to 38 emu/g, 60 G, and 2.1227 at 873 K. This method offers simplicity, a low cost, and an environmentally friendly operation since it produces no by-product effluents.
The project will focus on synthesis of hexagonal structured pure phases of compositions: BaM1/3Ti2/3O3-δ and BaM1/6Ti5/6O3-δ, where M= Sc, In and Fe via different methods such as Solid state sintering and wet chemical route. The ultimate goal is to finding structure – functionality relationships within these proton and mixed conducting systems. A substantial effort will focus on search for and fabrication of new materials although the main part of the work will concentrate on detailed structural characterisation (rietveld refinement), impedance spectroscopy, infrared spectroscopy and thermogravimetric analysis.
This document summarizes research on the optical and structural properties of tenorite (CuO) nanopowders doped with silicon (Si) and zirconium (Zr). Nanopowders were synthesized using a sol-gel method and calcined at temperatures from 400-700°C. X-ray diffraction analysis showed the samples crystallized in a tenorite structure and doping affected crystallinity and particle size. Optical absorption spectroscopy indicated undoped CuO has a direct bandgap of 1.78eV, while doped CuO (15% Si, 15% Zr) has a wider bandgap of 3.75-3.95eV. Scanning electron microscopy and other characterization techniques
Synthesis and Characterisation of Copper Oxide nanoparticlesIOSR Journals
Cupric oxide (CuO) nanoparticles were prepared by the chemical route by calcinations at a higher temperature from 300oC to 400 oC. For the comparison transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements were made through JCPDS. There is good agreement between data produced by spectroscopy and the microscopic measurements.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenetshankar20134
This document summarizes research on V-Mn-MCM-41 catalysts for the vapor phase oxidation of o-xylene. Mesoporous monometallic and bimetallic catalysts with varying ratios of vanadium and manganese were synthesized and characterized. Their activity for oxidizing o-xylene to phthalic anhydride was measured and found to correlate with their physical and chemical properties. The V-MCM-41 catalyst with a Si/V ratio of 50 exhibited the highest activity and selectivity. Vanadium species in the +5 oxidation state within the MCM-41 silica matrix were determined to be the active sites for selectively forming phthalic anhydride.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenemadlovescience
This document summarizes research on V-Mn-MCM-41 catalysts for the vapor phase oxidation of o-xylene. Mesoporous monometallic and bimetallic catalysts with varying ratios of vanadium and manganese were synthesized and characterized. Their activity for oxidizing o-xylene to phthalic anhydride was measured and found to correlate with their physical and chemical properties. The V-MCM-41 catalyst with a Si/V ratio of 50 exhibited the highest activity and selectivity. Vanadium in the +5 oxidation state present in the silica matrix was determined to be the active site for selectively forming phthalic anhydride.
The document summarizes research on the electrochemical deposition of lead dioxide nanostructured thin films. Key findings include:
- Lead dioxide nanostructures were successfully deposited on gold-coated substrates by anodic electrochemical deposition using nitric acid and lead chloride as reactants. The morphology was influenced by deposition parameters like potential, temperature, and pH.
- Deposition at higher temperatures (60°C vs room temperature) resulted in faster growth rates and denser nanostructures, as seen by SEM images.
- Both anodic and cathodic deposition were studied. Cathodic deposition allowed formation of different lead oxide phases depending on conditions, while anodic deposition selectively formed PbO2.
- The work provides a
Similar to Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured Materials for Catalytic Applications (20)
This document provides a technical review of secure banking using RSA and AES encryption methodologies. It discusses how RSA and AES are commonly used encryption standards for secure data transmission between ATMs and bank servers. The document first provides background on ATM security measures and risks of attacks. It then reviews related work analyzing encryption techniques. The document proposes using a one-time password in addition to a PIN for ATM authentication. It concludes that implementing encryption standards like RSA and AES can make transactions more secure and build trust in online banking.
This document analyzes the performance of various modulation schemes for achieving energy efficient communication over fading channels in wireless sensor networks. It finds that for long transmission distances, low-order modulations like BPSK are optimal due to their lower SNR requirements. However, as transmission distance decreases, higher-order modulations like 16-QAM and 64-QAM become more optimal since they can transmit more bits per symbol, outweighing their higher SNR needs. Simulations show lifetime extensions up to 550% are possible in short-range networks by using higher-order modulations instead of just BPSK. The optimal modulation depends on transmission distance and balancing the energy used by electronic components versus power amplifiers.
This document provides a review of mobility management techniques in vehicular ad hoc networks (VANETs). It discusses three modes of communication in VANETs: vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and hybrid vehicle (HV) communication. For each communication mode, different mobility management schemes are required due to their unique characteristics. The document also discusses mobility management challenges in VANETs and outlines some open research issues in improving mobility management for seamless communication in these dynamic networks.
This document provides a review of different techniques for segmenting brain MRI images to detect tumors. It compares the K-means and Fuzzy C-means clustering algorithms. K-means is an exclusive clustering algorithm that groups data points into distinct clusters, while Fuzzy C-means is an overlapping clustering algorithm that allows data points to belong to multiple clusters. The document finds that Fuzzy C-means requires more time for brain tumor detection compared to other methods like hierarchical clustering or K-means. It also reviews related work applying these clustering algorithms to segment brain MRI images.
1) The document simulates and compares the performance of AODV and DSDV routing protocols in a mobile ad hoc network under three conditions: when users are fixed, when users move towards the base station, and when users move away from the base station.
2) The results show that both protocols have higher packet delivery and lower packet loss when users are either fixed or moving towards the base station, since signal strength is better in those scenarios. Performance degrades when users move away from the base station due to weaker signals.
3) AODV generally has better performance than DSDV, with higher throughput and packet delivery rates observed across the different user mobility conditions.
This document describes the design and implementation of 4-bit QPSK and 256-bit QAM modulation techniques using MATLAB. It compares the two techniques based on SNR, BER, and efficiency. The key steps of implementing each technique in MATLAB are outlined, including generating random bits, modulation, adding noise, and measuring BER. Simulation results show scatter plots and eye diagrams of the modulated signals. A table compares the results, showing that 256-bit QAM provides better performance than 4-bit QPSK. The document concludes that QAM modulation is more effective for digital transmission systems.
The document proposes a hybrid technique using Anisotropic Scale Invariant Feature Transform (A-SIFT) and Robust Ensemble Support Vector Machine (RESVM) to accurately identify faces in images. A-SIFT improves upon traditional SIFT by applying anisotropic scaling to extract richer directional keypoints. Keypoints are processed with RESVM and hypothesis testing to increase accuracy above 95% by repeatedly reprocessing images until the threshold is met. The technique was tested on similar and different facial images and achieved better results than SIFT in retrieval time and reduced keypoints.
This document studies the effects of dielectric superstrate thickness on microstrip patch antenna parameters. Three types of probes-fed patch antennas (rectangular, circular, and square) were designed to operate at 2.4 GHz using Arlondiclad 880 substrate. The antennas were tested with and without an Arlondiclad 880 superstrate of varying thicknesses. It was found that adding a superstrate slightly degraded performance by lowering the resonant frequency and increasing return loss and VSWR, while decreasing bandwidth and gain. Specifically, increasing the superstrate thickness or dielectric constant resulted in greater changes to the antenna parameters.
This document describes a wireless environment monitoring system that utilizes soil energy as a sustainable power source for wireless sensors. The system uses a microbial fuel cell to generate electricity from the microbial activity in soil. Two microbial fuel cells were created using different soil types and various additives to produce different current and voltage outputs. An electronic circuit was designed on a printed circuit board with components like a microcontroller and ZigBee transceiver. Sensors for temperature and humidity were connected to the circuit to monitor the environment wirelessly. The system provides a low-cost way to power remote sensors without needing battery replacement and avoids the high costs of wiring a power source.
1) The document proposes a model for a frequency tunable inverted-F antenna that uses ferrite material.
2) The resonant frequency of the antenna can be significantly shifted from 2.41GHz to 3.15GHz, a 31% shift, by increasing the static magnetic field placed on the ferrite material.
3) Altering the permeability of the ferrite allows tuning of the antenna's resonant frequency without changing the physical dimensions, providing flexibility to operate over a wide frequency range.
This document summarizes a research paper that presents a speech enhancement method using stationary wavelet transform. The method first classifies speech into voiced, unvoiced, and silence regions based on short-time energy. It then applies different thresholding techniques to the wavelet coefficients of each region - modified hard thresholding for voiced speech, semi-soft thresholding for unvoiced speech, and setting coefficients to zero for silence. Experimental results using speech from the TIMIT database corrupted with white Gaussian noise at various SNR levels show improved performance over other popular denoising methods.
This document reviews the design of an energy-optimized wireless sensor node that encrypts data for transmission. It discusses how sensing schemes that group nodes into clusters and transmit aggregated data can reduce energy consumption compared to individual node transmissions. The proposed node design calculates the minimum transmission power needed based on received signal strength and uses a periodic sleep/wake cycle to optimize energy when not sensing or transmitting. It aims to encrypt data at both the node and network level to further optimize energy usage for wireless communication.
This document discusses group consumption modes. It analyzes factors that impact group consumption, including external environmental factors like technological developments enabling new forms of online and offline interactions, as well as internal motivational factors at both the group and individual level. The document then proposes that group consumption modes can be divided into four types based on two dimensions: vertical (group relationship intensity) and horizontal (consumption action period). These four types are instrument-oriented, information-oriented, enjoyment-oriented, and relationship-oriented consumption modes. Finally, the document notes that consumption modes are dynamic and can evolve over time.
The document summarizes a study of different microstrip patch antenna configurations with slotted ground planes. Three antenna designs were proposed and their performance evaluated through simulation: a conventional square patch, an elliptical patch, and a star-shaped patch. All antennas were mounted on an FR4 substrate. The effects of adding different slot patterns to the ground plane on resonance frequency, bandwidth, gain and efficiency were analyzed parametrically. Key findings were that reshaping the patch and adding slots increased bandwidth and shifted resonance frequency. The elliptical and star patches in particular performed better than the conventional design. Three antenna configurations were selected for fabrication and measurement based on the simulations: a conventional patch with a slot under the patch, an elliptical patch with slots
1) The document describes a study conducted to improve call drop rates in a GSM network through RF optimization.
2) Drive testing was performed before and after optimization using TEMS software to record network parameters like RxLevel, RxQuality, and events.
3) Analysis found call drops were occurring due to issues like handover failures between sectors, interference from adjacent channels, and overshooting due to antenna tilt.
4) Corrective actions taken included defining neighbors between sectors, adjusting frequencies to reduce interference, and lowering the mechanical tilt of an antenna.
5) Post-optimization drive testing showed improvements in RxLevel, RxQuality, and a reduction in dropped calls.
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Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured Materials for Catalytic Applications
1. IOSR Journal of Applied Chemistry (IOSR-JAC)
e-ISSN: 2278-5736.Volume 5, Issue 1 (Jul. – Aug. 2013), PP 23-29
www.iosrjournals.org
www.iosrjournals.org 23 | Page
Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia
Nanostructured Materials for Catalytic Applications
Cimi A Daniel, S.Sugunan
Department of Applied Chemistry, Cochin University of Science and Technology Cochin-682022, Kerala, India.
Abstract: CeO2–ZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl
ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by
XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder
particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size
is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified
to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by
the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards
liquid-phase oxidation of benzene.
Keywords- Mixed rare earth oxide, Ceria–zirconia, BET, TEM, benzene oxidation.
I. Introduction
In recent years, ceria and ceria containing material have been thoroughly investigated for the three way
catalyst (TWC) [1] application and oxidation catalysis (for example, diesel oxidation catalysts, DOC) because of
their oxygen storage capacity (OSC) based on the unique redox behaviour between Ce3+
and Ce4+
.[2, 3]
CeO2 is included in materials used in fuel-cell processes [4], in oxygen permeation membrane systems [5], and
as catalysts in numerous economically and technologically important industrial processes. The presence of CeO2
promotes various catalytic reactions such as CO2 activation, CO oxidation, CO/NO removal, low-temperature
water-gas shift 6reaction, oxidation of different hydrocarbons, wet oxidation processes of organic compounds,
the removal of total organic carbon from industrial wastewaters, methane reforming with CO2, SO2 reduction
with CO.
In the 1990s, many studies were committed to ZrO2–CeO2 oxides, notably to their synthesis and their
catalytic properties. [7–9] It is generally known that the incorporation of zirconium into the ceria lattice creates
a higher concentration of defects thus improving the O2−
mobility; such mobility would explain the outstanding
ability to store and release oxygen. [10] This property allows the oxidation of hydrocarbons and CO in rich
atmospheres.
Phenol, a valuable intermediate for the synthesis of agrochemicals, petrochemicals and plastics has
been mainly manufactured by the cumene process. But this multistep reaction generates phenol and acetone in
equimolar amounts. Hence the synthesis of phenol by direct hydroxylation of benzene is attractive both
economically and energetically. In the past, several catalysts have been examined using a number of oxidants.
Benzene oxidation using hydrogen peroxide has been explored by various researchers. [11–13] Transition metal
catalysts have also been demonstrated by researchers for the reaction in presence of comparatively costly
oxygen as the oxidant, and a reducing agent. [14, 15] Furthermore, benzene is considered as a priority pollutant
by the Environmental Protection Agency. Catalytic oxidation is considered as most promising method for its
effective removal.
In the present work, we report the synthesis of ceria zirconia mixed oxides, modification with
chromium, their structural characterization using different physico-chemical techniques. Activity of the catalysts
towards liquid phase oxidation of benzene is also investigated.
II. Materials and Methods
2.1. Experimental process
Ce (NO3)3.6H2O and ZrOCl2.8H2O were dissolved in a vessel with 500 mL deionized water to obtain
a cerium/zirconium mixed solution with a Ce/Zr mole ratio of 1:2. And then it was slowly added to a 500 mL
solution containing cetyl trimethyl ammonium bromide (surfactant/cerium nitrate=3.4 molar ratio) under
agitation, followed by adding NH4OH (28 wt %) into the mixture, the pH of the mixture was maintained at
around 11. The gel was loaded into a stoppered Teflon bottle and heated hydrothermally at 100ºC for 48 h. The
resultant solid was recovered by filtration, washing and then it was dried in air at 80°C for 12 h. Finally, the
sample was calcined at 600 °C for 4 h. It was then impregnated with an aqueous solution of chromium nitrate.
The volume of the aqueous solution of metal used for impregnation depended on the amount of the
2. Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured Materials for Catalytic
www.iosrjournals.org 24 | Page
support. The modified ceria-zirconia catalyst was dried at 120°C for 2 hrs and then it was calcined at 400°C for
4 h. The ceria zirconia support was denoted as CeZr and chromium modified catalyst as 1CrCeZr and 2CrCeZr.
2.2. Characterization
Nitrogen adsorption measurements were performed at liquid nitrogen temperature with a Micromeritics
Tristar 3000 surface area and porosity analyzer. XRD analysis was carried out using Rigaku D-Max Ni filtered
Cu Kradiation () diffractometer equipped with diffracted beam monochromator at a scan rate of
50/min analyzer. ICP-AES were done on Thermo electron IRIS INTERPID II XSP DUO model. FT-IR spectra
of the prepared samples were measured by the KBr pellet procedure over the range of 4000-500 cm-1 region
using JASCO FTIR spectrometer. Transmission Electron Microscopy was carried out in ultra high resolution
analytical electron microscope JEOL 3010. The sample was dispersed in ethanol through sonication and then
drop casted on a carbon-coated copper grid. Scanning electron micrographs was taken using JEOL Model JSM-
6390LV scanning electron microscope with a resolution of 1.38 eV. The powdered sample was dusted on a
double sided carbon tape, placed on a metal stub and was coated with a layer of gold to minimize charge effects.
Perkin Elmer TG analyzer instrument was used for carrying out thermo gravimetric studies. UV-VIS DR
spectra were taken in the range 200-800nm on Labomed UV-VIS double beam UVD-500 spectrophotometer
equipped with an integrating sphere assembly with a charged coupled device detector, using BaSO4 as
reflectance standard. Temperature-programmed desorption study of CO2 was carried out in Micromeritics Pulse
Chemisorb 2705.
2.3. Catalytic Activity
The liquid-phase oxidation of benzene was carried out in a 50 mL round bottom flask. In a typical
reaction, the catalyst powder was suspended in a mixture of acetonitrile (10 Ml) and benzene (2 mL) and kept in
the oil-bath. The oxidant, hydrogen peroxide (H2O2) was added to the system after attaining the reaction
temperature. The reaction mixture was stirred using a magnetic stirrer. About 0.5mL of solution was withdrawn
at regular intervals and analyzed on Chemito 8610 GC equipped with FID detector and an OV-17 packed
column. The products obtained were identified by comparison with standard ones. The catalytic activity was
expressed as the percentage conversion (wt%) of benzene and the selectivity for a product is expressed as the
amount of the particular product divided by total amount of products multiplied by 100.
III. Results And Discussions
The nitrogen sorption isotherms of ceria zirconia mixed oxides (CeZr) are shown in Fig. 1. It can be
classified as a type IV isotherm, typical of mesoporous material. The shape of the curve indicates the absence of
a narrow pore size distribution as suggested by the lack of the typical step in the adsorption isotherm which is
observed with ordered mesoporous structure. According to IUPAC classification, the hysteresis loop is of type
H2 indicating complex mesoporous structure.
Fig. 1. Nitrogen adsorption–desorption isotherm (a) and Pore size distribution (b) of CeZr.
The uptake at high pressure (P/P0~ 0.9–1.0) is associated with the void spaces between the
particles.[16 ]The presence of uni-modal mesopores are confirmed by the pore size distribution which shows
pore distribution covering the range 30-80 A° with a maximum at around 60 A° for mesoporous CeZr as
depicted in Figure 1. Surface area of the ceria zirconia sample was observed to be 70.1m2/g and on chromium
modification surface area was decreased to 57.9 m2/g. A substantial decrease in BET surface area after
impregnation is mainly due to the penetration of the dispersed chromia into the pores of the support.
X-ray diffraction pattern of prepared samples is shown in Fig. 2. Fig 2 shows the XRD patterns of
ceria-zirconia. XRD of the prepared material consists of all the peaks corresponding to the cubic fluorite
3. Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured Materials for Catalytic
www.iosrjournals.org 25 | Page
structure. The peaks were observed at 2θ~ 29.66, 34.12, 49.1, 58.28 in comparison with the pure ceria peaks at
2θ values of 28.78, 34.12, 47.68 and 56.48. [17, 18]. High 2θ values in the pattern reveal the presence of a
minor zirconia rich phase. Shift of peaks towards higher 2θ values is due to the small ionic radius of Zr 4+
(0.84A0
) in comparison with that of Ce 4+
(0.97A0
). All the diffraction patterns exhibit broad peaks suggesting
that as-prepared materials are nanocrystalline materials.
10 20 30 40 50 60 70 80
Intensity(A.U)
CeZr
Cr-CeZr
Fig. 2. XRD patterns of CeZr and 1CrCeZr.
FT-IR spectrum of representative catalysts is displayed in Figure 3. Broad absorption band located in the area
from 3200 to 3600 cm -1 corresponds to O-H stretching vibration. The peaks at 1640 cm-1 corresponds to H2O
bending vibration and at around 1340 cm-1 is due to Ce-OH stretching vibration. Band in the area from 400-700
cm -1 is due to the CeO2 stretching vibration. According to literature data [19] on the vibrational active modes
in the fluorite structure, absorption at around 460 cm-1 the main maximum would be assigned to the transverse
mode (TO) of the triply degenerated F1u fundamental, and the shoulder to the longitudinal component (LO) of
the same fundamental. The IR active mode in the 600–650 cm-1 range is caused by asymmetrically coupled
asymmetric Zr–O–Zr stretching, and the mode arising from the symmetric Zr–O–Zr stretching is revealed in the
400–500 cm-1 region. [20]
4000 3500 3000 2500 2000 1500 1000 500
0
20
40
60
80
100
Intensity(a.u)
Wavenumber (cm
-1
)
Ce0.25Zr0.75O2
Fig. 3. FT-IR spectrum of CeZr.
The morphology analysis was carried out and is shown in figure 4, 5 and 6. It can be seen from Fig.4 that
majority of the ceria crystals consists of aggregated small crystallites of a few nanometres and very
homogeneous in size. Sample shows mesoscopic ordering as observed from HRTEM. The lattice fringes of
nanocrystalline zirconia can also be well detected by the high resolution TEM image. The selected area electron
diffraction (Fig 4d) pattern of the sample exhibited continuous concentric rings, implying that the samples
consisted of many very small crystallites with well-defined lattice planes. Average particle size is 12-13 nm as
calculated from particle histogram (Fig 4e). Figure 5 shows the HRTEM and SAED pattern of chromia
modified sample. Figure 6 contain scanning electron microscopic pictures of some representative catalysts.
After calcination, the particles become irregular shaped and larger sized due to the collapse in structure after
heat treatment.
4. Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured Materials for Catalytic
www.iosrjournals.org 26 | Page
Fig. 4. HR-TEM, SAED pattern (d) and particle size histogram (e) of CeZr.
Fig. 5. HR-TEM, SAED pattern of 2CrCeZr.
Fig. 6. SEM image of CeZr.
5. Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured Materials for Catalytic
www.iosrjournals.org 27 | Page
Thermogram corresponding to Ce-Zr mixed oxide shows weight loss at 206 °C which is attributed to the
removal of structural hydroxyl group(Fig 7). A small weight loss at 311°C may be due to the removal of
surfactant. Weight loss at around 440 °C can be due to the transition from amorphous into crystalline form.
100 200 300 400 500 600 700 800
75
80
85
90
95
100
Weightloss
Temperature
C
-0.2
-0.1
0.0
DTG
TGA
Fig.7. TG-DTA analysis of CeZr.
The spectra, in general, are broad and exhibited a myriad of poorly resolved peaks. Broad absorption bands are
observed in the range of 200–350 nm (Fig 8). These bands are attributed to localized O–Ce charge transfer
transitions involving a number of surface Ce 4+ ions with different coordination numbers 21. Interband and 02--
Zr4+ transitions of substituted fluorite lattice 22 occur prominently around 340nm.
TPD spectrum of CO2 obtained after CO2 adsorption is shown in Fig.9. Two desorption peaks appear at
199°C and 369°C. It is clear that there are two kinds of CO2 adsorption sites on CeO2-ZrO2 surface indicating
two kinds of basic sites on the surface of the catalyst. The peak at lower temperature may be assigned to a
monodentate carbonate interacting with CeO2-ZrO2. The desorption peak at a higher temperature may be
assigned to a bidentate carbonate. The latter species being bonded to the oxide surface by two lattice oxygen
ions should exhibit a higher thermal stability than the former ones. [23, 24]
Fig. 8. DR UV-vis spectra of CeZr. Fig.9. TPD -CO2 after CO2 adsorption on CeZr
200 300 400 500 600 700 800
Intensity(A.U)
Wavelength(nm)
IV. Catalytic activity: Oxidation of benzene
The catalysts prepared were used in a one-step liquid-phase oxidation of benzene with H2O2 as the
oxidant and acetonitrile as the solvent.
The effect of temperature on the oxidation of benzene was studied by performing the reaction at three
different temperatures over chromia modified ceria zirconia with other parameters kept constant and the results
are shown in Fig.10. The best results were obtained at 60 0
C. When the reaction temperature rose up to 343 K, a
sharp increase in the oxidation activity (51%) and phenol selectivity (85%) was observed. Further increase of
temperature decreased the activity as well as phenol yield. This may arise due to the phenol being further
oxidized to hydroquinone and 1,4-benzoquinone at the higher temperature. Vaporization of benzene can also
occur at this temperature which can result in the decreased activity. [25]
6. Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured Materials for Catalytic
www.iosrjournals.org 28 | Page
50 60 70
0
10
20
30
40
50
60
70
80
90
100
Conversion(%)
Time (hrs)
Conversion
Phenol Selectivity
CeZr 1CrCeZr 2CrCeZr
0
10
20
30
40
50
60
70
80
90
100
Conversion(%)
Catalyst
Conversion
Selectivity
Fig. 10. The effect of temperature on benzene
oxidation with Cr-CeZr as the catalyst
Fig. 11. The oxidation of benzene over catalyst with
different metal loading.
(Catalyst mass = 100 mg, Benzene: H2O2 = 1:2 ratio (vol); acetonitrile = 10ml and reaction time=5h).
Benzene was oxidized using catalyst with different metal loadings under the optimum reaction conditions at 60
0
C (Fig 11). When the amount of chromium increased, the benzene conversion is increased. So the oxidation
rate directly depends on the metal content.
For the oxidation of aromatics with hydrogen peroxide over modified metal oxides, it has been
proposed that the hydroxylation of the aromatic ring occurs via the heterolytic mechanism, involving the
formation of a metalloperoxide species [26–30]. We have not carried out any mechanistic studies in the present
work, it is tentatively suggested that a heterolytic cleavage of hydrogen peroxide proceeds via the formation of
metallo peroxide. Similar observations have been noticed in literature over metal oxide dispersed analogues [31,
32].
V. Conclusions
Nanocrystalline powders of ceria zirconia mixed oxides were successfully synthesized using CTAB as
surfactant via hydrothermal method. The technique used here is simple and cost effective. The X-ray diffraction
(XRD) analysis suggests that as-prepared materials are nanocrystalline materials. The nitrogen
adsorption/desorption isotherm can be classified as a type IV isotherm and hysteresis loop is of type H2
indicating complex mesoporous structure. Pore size distribution which shows pore distribution covering the
range 30-80 A° with a maximum at around 60 A°. HRTEM investigation reveals the existence of several nano
crystallites with well defined lattice planes. Average particle size is 12-13 nm as calculated from particle
histogram. A single step oxidation of benzene to phenol under mild reaction conditions was carried out
successfully over supported ceria zirconia mixed oxide as catalysts with H2O2. Incorporation of chromia
exhibited a promoting effect towards the oxidation reaction. The obtained results suggest the scope of tailoring
reaction engineering design for better utilization of this system.
Acknowledgement
We would like to thank Indian Rare Earths Ltd. for the funding which was used to support this work.
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