Control of Particle Morphology and Size in Vapor-Phase Synthesis of Titania, Silica and Alumina Nanoparticles
01 Jan 2015-Kona Powder and Particle Journal (Hosokawa Powder Technology Foundation)-Vol. 32, pp 85-101
TL;DR: In this paper, a review of previous studies on vapor-phase synthesis of titania (TiO2), silica (SiO2) and alumina (Al2O3) nanoparticles is presented.
Abstract: Previous studies on vapor-phase synthesis of titania (TiO2), silica (SiO2), and alumina (Al2O3) nanoparticles were reviewed. Interactions between physicochemical phenomena involved in the particle growth and the operating variables were investigated. Strategies to produce non-aggregated spherical particles of the metal oxides are discussed. Model predictions based on the sintering laws without any adjustments in the sintering parameters rarely agreed with experimental data. There remains more to be understood in reaction and nucleation kinetics, sintering, and fragmentation mechanisms until the technology is developed to the stage of designing reactors for mass production of non-aggregated spherical particles for titania, silica and alumina
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TL;DR: The present review covers the physiology of skin, burn classification, burn wound pathogenesis, animal models of burn wound infection, and various topical therapeutic approaches designed to combat infection and stimulate healing, including biological based approaches and nanotechnology-based wound healing approaches as a revolutionizing area.
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Cites background from "Control of Particle Morphology and ..."
...• Ceramic NPs: Ceramic NPs include oxides, carbides, phosphates, carbonates, calcium, and generally have porous structures such as silicon oxide (silica) and aluminum oxide (alumina) [241, 242]....
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TL;DR: The metal-support interaction that is vital for redox catalytic performance for various surface reactions is presented and noble metal stabilized oxide matrices with tight chemical contact catalyze surface reactions for enhanced catalysttic performance are presented.
Abstract: Flame spray pyrolysis of precursor-solvent combinations with high enthalpy density allows the design of functional nanoscale materials. Within the last two decades, flame spray pyrolysis was utilized to produce more than 500 metal oxide particulate materials for R&D and commercial applications. In this short review, the particle formation mechanism is described based on the micro-explosions observed in single droplet experiments for various precursor-solvent combinations. While layer fabrication is a key to successful industrial applications toward gas sensors, catalysis, and energy storage, the state-of-the-art technology of innovative in situ thermophoretic particle production and deposition technology is described. In addition, noble metal stabilized oxide matrices with tight chemical contact catalyze surface reactions for enhanced catalytic performance. The metal-support interaction that is vital for redox catalytic performance for various surface reactions is presented.
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TL;DR: In this article, the authors proposed a project which was partly funded by the National Research Foundation (NRF), Prime Minister's Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme.
32 citations
Cites background from "Control of Particle Morphology and ..."
...Park and Park (2015) discuss the role of these different factors and summarise the difficulties inherent in understanding and controlling the synthesis process.20 Reactors for the industrial synthesis of titanium dioxide often have multiple feed points, with independently controlled feed rates and…...
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...Alternate215 expressions for τc are available (Park and Park, 2015). τc = 7.4× 108Td4i,j exp ( 3.1× 104 T ) (12) The sintering level si,j between the primary particle pairs in each particle is given by Eq....
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TL;DR: In this article, a specific flame spray pyrolysis method, Liquid Flame Spray (LFS), is introduced to produce nanoparticles using a coflow type hydrogen-oxygen flame utilizing pneumatically sprayed liquid precursor.
Abstract: In this review article, a specific flame spray pyrolysis method, Liquid Flame Spray (LFS), is introduced to produce nanoparticles using a coflow type hydrogen-oxygen flame utilizing pneumatically sprayed liquid precursor. This method has been widely used in several applications due to its characteristic features, from producing nanopowders and nanostructured functional coatings to colouring of art glass and generating test aerosols. These special characteristics will be described via the example applications where the LFS has been applied in the past 20 years.
21 citations
Cites methods from "Control of Particle Morphology and ..."
...The FSP method generates well-defined nanoparticulate material which can be collected as a powder from the exhaust aerosol of the flame (Stepuk et al., 2013; Park and Park, 2015) or sprayed on a surface (Mishra et al....
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...The FSP method generates well-defined nanoparticulate material which can be collected as a powder from the exhaust aerosol of the flame (Stepuk et al., 2013; Park and Park, 2015) or sprayed on a surface (Mishra et al., 2014)....
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TL;DR: In this article, the hierarchical structure of superamphiphobic surfaces is tuned in order to rapidly rupture contacting bubbles and demonstrate excellent mechanical and chemical stability even in the presence of surface active species.
Abstract: Controlling bubble motion or passively bursting bubbles using solid interfaces is advantageous in numerous industrial applications including flotation, catalysis, electrochemical processes, and microfluidics. Current research has explored the formation, dissolution, pinning, and rupturing of bubbles on different surfaces. However, the ability to tune and control the rate of bubble bursting is not yet achieved. Scaling down surface-induced bubble bursting to just a few milliseconds is important for any application. In this work, the hierarchical structure of superamphiphobic surfaces is tuned in order to rapidly rupture contacting bubbles. Surfaces prepared using liquid flame spray show ultrafast bubble bursting (down to 2 ms) and superior durability. The coatings demonstrate excellent mechanical and chemical stability even in the presence of surface-active species. Air from the ruptured bubble is absorbed into the aerophilic Cassie-state. Long-term applicability is demonstrated by preventing the accumulation of air in the plastron via a connection of the plastron to the environment. The times recorded for bubble rupture and complete reorganization of air are reduced by approximately a factor of 3 compared to previously reported values. The concept is utilized to passively control surfactant-rich foam in froth flotation. Material collection efficiency increased by more than 60 times compared to controls.
16 citations
References
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01 Mar 2000
TL;DR: In this paper, the authors investigated the effect of the size distribution function on the performance of a single element particle capture by diffusion and interception at high Reynolds numbers and showed that the effects of the distribution function are independent of the particle size.
Abstract: 1. AEROSOL CHARACTERIZATION Parameters Determining Aerosol Behavior Particle Size Particle Concentration Size Distribution Function Moments of the Distribution Function Examples of Size Distribution Functions Chemical Composition Aerosol Dynamics: Relation to Characterization 2. PARTICLE TRANSPORT PROPERTIES Equation of Diffusion Coefficient of Diffusion Friction Coefficient Agglomerate Diffusion Coefficients Path Length of a Brownian Particle Migration in an External Force Field Electrical Migration Thermophoresis London-van der Waals Forces Boundary Condition for Particle Diffusion 3. CONVECTIVE DIFFUSION: EFFECTS OF FINITE PARTICLE DIAMETER AND EXTERNAL FORCE FIELDS Equation of Convective Diffusion Similitude Considerations for Aerosol Diffusion Concentration Boundary Layer Diffusion to Cylinders at Low Reynolds Numbers: Concentration Boundary Layer Equation Diffusion at Low Reynolds Numbers: Similitude Law for Particles of Finite Diameter Low Re Deposition: Comparison of Theory with Experiment Single Element Particle Capture by Diffusion and Interception at High Reynolds Numbers High Re Deposition: Application to Deposition on Rough Surfaces Diffusion from a Laminar Pipe Flow Diffusion from a Turbulent Pipe Flow Particle Deposition from Rising Bubbles Convective Diffusion in an External Force Field: Electrical Precipitation Thermophoresis: "Dust Free Space" 4. INERTIAL TRANSPORT AND DEPOSITION Particle-Surface Interactions: Low Speeds Particle-Surface Interactions: Rebound Particle Acceleration at Low Reynolds Numbers: Stop Distance Similitude Law for Impaction: Stokesian Particles Impaction of Stokesian Particles on Cylinders and Spheres Impaction of Non-Stokesian Particles Deposition from a Rotating Flow: Cyclone Separator Particle Eddy Diffusion Coefficient Turbulent Deposition Aerodynamic Focusing: Aerosol Beams Transition from the Diffusion to Inertial Ranges 5. LIGHT SCATTERING Scattering by Single Particles: General Considerations Scattering by Particles Small Compared to the Wavelength Scattering by Large Particles: The Extinction Paradox Scattering in the Intermediate Size Range: Mie Theory Scattering by Aerosol Clouds Scattering over the Visible Wavelength Range: Aerosol Contributions by Volume Rayleigh Scattering: Self-Similar Size Distributions Mie Scattering: Power Law Distributions Quasi-Elastic Light Scattering Specific Intensity: Equation of Radiative Transfer Equation of Radiative Transfer: Formal Solution Light Transmission Through the Atmosphere: Visibility Inelastic Scattering: Raman Effect 6. EXPERIMENTAL METHODS Sampling Microscopy Mass Concentration: Filtration Total Number Concentration: Condensation Particle Counter Total Light Scattering and Extinction Coefficients Size Distribution Function Mass and Chemical Species Distribution: The Cascade Impactor Aerosol Chemical Analysis Summary Classification of Measurment Instruments Monodisperse Aerosol Generators 7. COLLISION AND COAGULATION: COALESCING PARTICLES Introduction Collision Frequency Function Brownian Coagulation Brownian Coagulation: Dynamics of Discrete Distribution for an Intially Monodisperse Aerosol Brownian Coagulation: Effect of Particle Force Fields Effect of van der Waals Forces Effect of Coulomb Forces Collision Frequency for Laminar Shear Simultaneous Laminar Shear and Brownian Motion Turbulent Coagulation Equation of Coagulation: Continuous Distribution Function Similarity Solution: Coagulation in the Continuum Regime Similarity Solution for Brownian Coagulation Similarity Solution: Coagulation in the Free Molecule Region Time to Reach the Self-Preserving Distribution (SPD) 8. DYNAMICS OF AGGLOMERATE FORMATION AND RESTRUCTURING Agglomerate Morphology: Scaling Laws Computer Simulation of Agglomerate Formation Langevin Simulations of Agglomeration Smoluchowski Equation: Collision Kernals for Power Law Aggregates Self-Preserving Agglomerate Size Distributions Effect of Primary Particle Size on Agglomerate Growth Effect of Df on Agglomearte Growth Agglomerate Restructuring 9. THERMODYNAMICS PROPERTIES The Vapor Pressure Curve and the Supersaturated State Effects of Solutes on Vapor Pressure Vapor Pressure of a Small Particle Hygroscopic Particle-Vapor Equilibrium Charged Particle-Vapor Equilibria Solid Particle-Vapor Equilibrium Effect of Particle Size on the Equilibrium of a Heterogeneous Chemical Reaction Molecular Clusters 10. GAS-TO-PARTICLE CONVERSION Condensation by Adiabatic Expansion: The Experiments of C.T.R. Wilson Kinetics of Homogeneous Nucleation Experimental Test of Nucleation Theory Heterogeneous Condensation Growth Laws Dynamics of Growth: Continuity Relation in v Space Measurement of Growth Rates: Homogeneous Gas-Phase Reactions Simultaneous Homogeneous and Heterogeneous Condensation Effects of Turbulence on Homogeneous Nucleation 11. THE GENERAL DYNAMIC EQUATION FOR THE PARTICLE SIZE DISTRIBUTION FUNCTION General Dynamic Equation for the Discrete Distribution Function Coagulation and Nucleation as Limiting Processes in Gas-to-Particle Conversion General Dynamic Equation for the Continuous Distribution Function The Dynamic Equation for the Number Concentration N The Dynamic Equation for the Volume Fraction Simultaneous Coagulation and Diffusional Growth: Similarity Solution for Continuum Regime Simultaneous Coagulation and Growth: Experimental Results The GDE for Turbulent Flow The GDE for Turbulent Stack Plumes Coagulation and Stirred Settling Coagulation and Deposition by Convective Diffusion Continuously Stirred Tank Reactor 12. SYNTHESIS OF SUBMICRON SOLID PARTICLES: AEROSOL REACTORS Aerosol Reactors: Commercial and Pilot Scale The Collision-Coalescence Mechanism of Primary Particle Formation Extension of the Smouluchowski Equation to Colliding, Coalescing Particles Rate Equation for Particle Coalescence Solid-State Diffusion Coefficient Estimation of Average Primary Particle Size: Method of Characteristic Times Primary Particle Size: Effects of Aerosol Material Properties Particle Neck Formation Particle Crystal Structure 13. ATMOSPHERIC AEROSOL DYNAMICS Atmospheric Aerosol Size Distribution Aerosol Dynamics in Power Plant Plumes Chemical Composition of Urban Aerosols Distributions of Chemical Species with Particle Size Morphological Characteristics of the Submicron Aerosol Common Measures of Air Quality for Particulate Matter: Federal Standards Receptor Modeling: Source Apportionment Statistical Variations of Ambient Aerosol Chemical Components EACH CHAPTER ENDS WITH PROBLEMS AND REFERENCES Common Symbols Index
1,047 citations
TL;DR: In this article, an overview of the history of flame aerosol technology and current state of knowledge on the role of flame process variables (additives, mixing etc.) on the characteristics of product powders is summarized in a tutorial fashion.
830 citations
TL;DR: In this article, the particle density has long-range correlations of the same form in iron, zinc or silicon dioxide aggregates, and the correlation data suggest a power-law spatial dependence giving a Hausdorff dimension between 1.7 and 1.9.
Abstract: Ultrafine smoke particles stick together to form chain-like aggregates. We find that the particle density has long-range correlations of the same form in iron, zinc or silicon dioxide aggregates. The correlation data suggest a power-law spatial dependence giving a Hausdorff dimension between 1.7 and 1.9. We discuss the consistency of these results with a model based on percolation. We also compare our results with a random-walk model, which has a nominal Hausdorff dimension of 2.
637 citations
TL;DR: An overview of methods for preparing nanoparticles in the vapor phase is given in this paper, and recent advances in instrumentation for monitoring vapor-phase synthesis of nanoparticles and in modeling these processes are also included.
Abstract: An overview of methods for preparing nanoparticles in the vapor phase is given, and recent advances are reviewed Developments in instrumentation for monitoring vapor-phase synthesis of nanoparticles and in modeling these processes are also included The most important developments relate to improved control and understanding of nanoparticle aggregation and coalescence during synthesis, and to methods for producing multi-component nanoparticles
603 citations
TL;DR: In this article, the authors classified flame processes into vapour-fed and liquid-fed ones depending on the employed state of the metal precursor, and distinguished them for their flexibility in producing materials of various compositions and morphologies that result in unique product functionalities.
Abstract: Recent advances in aerosol and combustion science and engineering now allow scalable flame synthesis of mixed oxides, metal salts and even pure metals in the form of nanoparticles and films with closely controlled characteristics. In this way, high purity materials with novel metastable phases are made that are not accessible by conventional wet-phase and solid state processes. Here, flame processes are classified into vapour-fed and liquid-fed ones depending on the employed state of the metal precursor. Liquid-fed flame processes are distinguished for their flexibility in producing materials of various compositions and morphologies that result in unique product functionalities. Parameters controlling the characteristics of flame-made particles and films are summarized and selected classes of materials are reviewed focusing on catalysts, sensors, biomaterials (orthopaedic, dental or nutritional), electroceramics (fuel cells, batteries) and phosphors exhibiting superior performance over conventionally made ones. Just a few years ago it seemed impossible to make these materials in the gas phase. Finally, health effects of such particles are discussed while future challenges and opportunities for flame-made materials are highlighted.
527 citations