Aerosols produced by x-rays.
Keng-EY; Chu-RR; Knight-JA Jr.; Orr-C Jr.
J Colloid and Interface Sci 1972 Apr; 39(1):94-102
The formation of aerosols of organic vapors by X-rays was studied. Air containing organic vapors was exposed to X-rays at the maximum output of an X-ray unit, about 2,000,000 roentgens per minute. Aerosols were collected on metal oxide whiskers, by a thermal precipitator, or on Millipore filters. Size distributions were obtained by electron microscopy and aerosol mean concentrations were computed. Concentrations of benzene (71432) or acetylene (74862) were increased from 0.1 to 10,000 parts per million and quantity of particulates formed was measured. X-ray intensity was then varied as a function of rectified tube current from 0 to 0.05 Amperes. The dependence of particulate function on irradiation time was also studied at irradiation times of 0 to 15 minutes. Growth of particulates was evaluated as a function of aging time after exposure for periods from 0 to 100 minutes. Particulate concentrations from air containing benzene and acetylene were studied after 4 minutes of maximum irradiation at relative humidities from 0 to 100 percent. To study the chemical structures of particulates formed, infrared analysis was used for particles formed by irradiation of air containing benzene and acetylene. Particulates formed by X-rays in air were spherical, of sub micrometer size, and essentially nonvolatile. The mass concentration of the particles increased with the concentration of organic vapor in the air. Acetylene produced a smaller quantity of particulates than benzene. Mass concentration also increased with increasing X-ray intensity, irradiation time, and aging time after exposure. Mass concentration increased with relative humidity to about 5 percent and then decreased with further increases in humidity. Particulate size increased with higher humidity. Infrared analysis indicated the presence of acetylene and aromatic type structures with carbonyl groups.
NIOSH-Grant; Research; Analytical-chemistry; Ionizing-radiation; Chemical-synthesis; Organic-chemicals; Decomposition-products; Aerosol-particles; Dust-analysis; Airborne-particles; Quantitative-analysis; Trace-analysis
Micromeritics Engineering Experiment Station 225 North Avenue, N W Atlanta, GA 30332
Journal of Colloid and Interface Science
Georgia Institute of Technology, Atlanta, Georgia