Chemical and Biological Engineering ETDs

Tom B. Larsen

Publication Date

1971

Abstract

Simple, dependable methods for the generation of aerosols are necessary to many forms of research. Specifically inhal­ation research has a requirement for sub-micron sized insoluble particles.

Two different methods for the production of oxide aerosols from vaporizable compounds were tried. The first method, a mod­ification of the Rapaport-Weinstock generator (R3), consisted of nebulization of a solution into a droplet mist. Next the drop­lets were vaporized, and condensation nuclei formed from the nonvaporizable impurities in the solution. The vapor was allowed to condense on the nuclei in a relatively large chamber, then the resulting liquid droplet aerosol was dried and converted to the oxide form in a high temperature heating column. The second method was new, in that, compounds in the solid state, were vaporized, and then condensed on nuclei. Condensation nuclei for this method were provided by either of two different tech­niques. The first one consisted of the nebulization of dilute metal nitrate solutions, followed by drying, and then degradation to the oxide form. In the second, a part of the vapor from the solid compound was directly converted to the oxide. The proced­ures of condensation, and ultimate conversion to the oxide, were carried out in a manner identical to the first method. This method shows great promise for the production of very small oxide par­ticles, of minimal size distribution.

Both methods were used to generate oxide aerosols of aluminum, cobalt, lanthanum, yttrium or zirconium, with particle diameters ranging from 0.018 to 1.08 microns. The major results of, and the important conclusions drawn from the work were:

  1. Due to hydrate formation, only limited droplet evap­oration was achieved using the first method, this re­sulted in the formation of particles with a large size distribution. A baffle within the condenser was found to screen out the largest and smallest particles, re­sulting in the production of more uniform sized par­ticles.
  2. Method two, in which condensation nuclei were formed by partial degradation of the vapor, produced small particles (from 0.018 to 0.078 microns in diameter). This method is suitable for the generation of sub-mi­cron sized radioactive oxide aerosols, and withJI1inor modifications it could be used for the production of monodispersed aerosols.

Document Type

Thesis

Language

English

Degree Name

Chemical Engineering

Level of Degree

Masters

Department Name

Chemical and Biological Engineering

First Committee Member (Chair)

Richard E. Dascher

Second Committee Member

James H. Turner

Third Committee Member

Thomas T. Castonguay

Fourth Committee Member

George Heinz Quentin

Fifth Committee Member

George M. Kanapilly

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