In U.S. Patent Application 20090317336, Battelle Memorial Institute (Columbus, Ohio) inventors Amit Gupta (Richland WA), William C. Forsythe and Mark L Clark disclose a method and apparatus for generating high purity nanoparticles, including fullerenes, carbon nanotubes, titanium dioxide and cerium oxide (CeO) at high concentration
The apparatus uses a solid aerosol disperser in communication with a furnace tube having a vaporization chamber and a dilution chamber. A heating element surrounds the furnace tube. Heat from the heating element heats bulk materials contained within a gas flow in the vaporization chamber to a temperature sufficient to convert the bulk materials to a vapor phase.
Vaporized bulk materials are then moved to a dilution chamber, where an inert gas is introduced through a dilution gas port. The flow of the inert gas into the dilution chamber through the dilution gas port is sufficient to eject the bulk material from the exit of the dilution chamber, thereby condensing the bulk material into nano sized particles in a gas flow of sufficient volume to prevent agglomeration of the nano sized particles.
The nanomaterials generated by the apparatus are suitable for use in applications requiring high concentration and high purity, including inhalation toxicology studies, manufacturing applications, occupational safety and health studies, and as drug delivery systems.
The manufacturing method is particularly well suited and enables the generation of high concentrations of nano-sized particles of C60 aerosols. It is also well suited to the production of cerium oxide, carbon nanotubes, titanium dioxide, C70, C76, and C84. The apparatus features the use of a solid aerosol disperser.
While these commercially available solid aerosol dispersers can be configured to provide a flow of solid particles in a gaseous flow, the particle size of their output is not sufficiently small to meet the objectives of the Battelle apparatus.
For example, and not meant to be limiting, beginning by milling commercially available bulk material consisting of C60 particles supplied by SES Research, Houston, Tex., the solid aerosol disperser available from Battelle Memorial Institute (Columbus, Ohio), can then provide a constant flow of C60 having particles sized between about 1 .mu.m and about 1.5 .mu.m mass median aerodynamic diameter (MMAD) in a flow of nitrogen of about 6-6.5 LPM.
Battelle’s invention provides a method whereby those particles are reduced further in size while maintaining purity, such that the resulting particles are of less than 100 nm count median diameter (CMD) and do not exhibit chemical decomposition of C60 to an amorphous phase or to carbon black. Accordingly, the "nano sized particles" produced by the Battelle invention are defined herein as particles having less than 100 nm count median diameter (CMD).