Aerosol Processing of Materials

Gurav, Abhijit; Kodas, Toivo; Pluym, Tammy; Xiong, Yun

doi:10.1080/02786829308959650

Cited by 381 publications

(248 citation statements)

References 305 publications

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“…Several reports exist on the formation of inorganic oxides in high-temperature environments. 105,173 Yang and Biswas 174 have performed extensive light-scattering measurements to evaluate the sintering characteristics of titania particles. A comparison of characteristic times for formation by chemical reaction, coagulation, and sintering can be used to ensure that large agglomerated structures with very high surface areas form in the combustor.…”

Section: Sorbent Oxide Formation Andmentioning

confidence: 99%

Control of Toxic Metal Emissions from Combustors Using Sorbents: A Review

Biswas

1998

Journal of the Air & Waste Management Association

172

123

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This paper constitutes a review of the control of toxic metal emissions using sorbents. The objective of sorbent-injection methods is to effectively capture the metal species (preferably transform it to an environmentally benign form) and to suppress the fraction in the submicrometer mode. The design of an effective sorbent-injection methodology thus requires an understanding of the fate of the metallic species and its transformation pathways (transfer to the gas phase, subsequent chemistry at high temperatures, and aerosol formation and growth dynamics) in the combustor. Several different sorbent methodologies used for metals capture are discussed, and a mechanistic description is provided. The need for further experimentation and pilot scale testing is also emphasized.

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Section: Sorbent Oxide Formation Andmentioning

confidence: 99%

Control of Toxic Metal Emissions from Combustors Using Sorbents: A Review

Biswas

1998

Journal of the Air & Waste Management Association

172

123

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“…The growth of particles in the gas phase by thermally driven collisions between particles (coagulation), particles and molecular clusters, and particles and vapor molecules (condensation/surface growth) plays a critical role in a number of aerosol processes, including new particle formation in the atmosphere (Kuang et al 2009) and nanomaterials synthesis (Gurav et al 1993;Swihart 2003). The behavior of these systems is largely governed by the collision rate, R (the number of collisions per unit time per unit volume of aerosol), the calculation of which is simplified by the fact that particles, clusters, and vapor molecules are typically found at low volume fractions in the gas phase.…”

Section: Introductionmentioning

confidence: 99%

Determination of the Transition Regime Collision Kernel from Mean First Passage Times

Gopalakrishnan

Hogan

2011

Aerosol Science and Technology

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Particle-vapor molecule (condensation) and particle-particle (coagulation) collision kernels are critically important parameters for the description of particle size distribution evolution in aerosols. We use mean first passage time calculations to find a dimensionless form of the collision kernel that applies in the limit where the ratio of the masses of colliding entities (aerosol particles or vapor molecules) to gas molecule mass, Z, approaches infinity, and the colliding entities are dilute in concentration. In these calculations, the motion of colliding entities is monitored with Langevin dynamics, and the collision kernel is inferred from the time required for collision. The presented analysis reveals that the dimensionless collisional kernel (H) is a function solely of the diffusive Knudsen number (Kn D , the square root of the product of kT and the reduced mass divided by the product of the reduced friction factor and collision radius), and a number of commonly used expressions for the collision kernel also collapse to the functional form H(Kn D ), irrespective of whether they were derived for Z → ∞ or Z → 0 conditions. The examined collision kernel expressions are further found to agree within 10% of our calculations as well as with each other across the entire Kn D range. This result suggests that a single collision kernel can be used to describe all transition regime collision rates, i.e., both condensation and coagulation rates, with reasonable accuracy, and establishes that Langevin-equationbased mean first passage time calculations can serve as a simple approach to examine transition regime collision phenomena.

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“…In order to make clear the differences between this work and that of other authors, we refer to an excellent review article on the aerosol processing of materials (Gurav et al 1993), in which ame reactors and spray pyrolysis are considered in some detail. These are the two processes relevant to the following presentation.…”

Section: Introductionmentioning

confidence: 99%

A Novel Aerosol Combustion Process for the High Rate Formation of Nanoscale Oxide Particles

Kilian¹,

Morse²

2001

Aerosol Science and Technology

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We report a new method for the high rate formation of nanophase ZrO 2 and Al 2 O 3 powders. In the experimental arrangement, a solution of metal alkoxides in their parent alcohols is converted into an aerosol of approximately 30 ¹ diameter droplets by means of an ultrasonic spray nozzle. The aerosol is mixed with oxygen immediately after formation and combusted in a specially designed burner at high temperature. The resulting oxide particles are thermophoretically collected and examined using TEM and X-ray diffractometry. A novel, patented, burner design permits a signicant reduction in temperature gradients normal to the ame. As a consequence, it is possible to obtain signi cantly better control over particle size and morphology and, in addition, hard agglomerates are absent. This is a signi cant departure from the process found in a typical ame reactor. With this technique, spherical, unnecked particles in the range from 5 to 140 nm (peaking sharply at 40 nm) are produced. There is no correlation between the initial liquid droplet size and the nal particle size. The method was successfully applied to the formation of zirconium and aluminum oxide at synthesis rates in excess of 3 g/min. Experiments to measure the ame temperature using an optical technique yielded temperatures between 2300 K and 3000 K, depending on the position in the ame and the type of precursor solution used. We note that this technique can be readily extended to more complex oxides such as YAG and BaSrTiO 3 . INTRODUCTIONDuring the past several years a large number of methods for the production of nanoscale oxide particles have been reported. Oxide powders with particles sizes in the range below 100 nm are important in many applications that include ceramic products, catalysts, and paint opaci ers. The approaches taken in their synthesis can be divided into wet chemical and gas phase (aerosol) methods. Among the former is the precipitation of particles from a suitable homogeneous precursor solution (Ciftcioglo and Majo 1990) and the wet hydrolysis of metal alkoxides in solution (Smith et al.; Ingebrethsen and Matijevi).

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Aerosol Processing of Materials

Cited by 381 publications

References 305 publications

Control of Toxic Metal Emissions from Combustors Using Sorbents: A Review

Control of Toxic Metal Emissions from Combustors Using Sorbents: A Review

Determination of the Transition Regime Collision Kernel from Mean First Passage Times

A Novel Aerosol Combustion Process for the High Rate Formation of Nanoscale Oxide Particles

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