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2814922 
Journal Article 
A Gravimetric System to Study Adsorption on Fine Particle Powders 
Gorski, CH; Stettler, LE 
1971 
Yes 
Journal of Colloid and Interface Science
ISSN: 0021-9797
EISSN: 1095-7103 
NIOSH/00131141 
37 
4 
918-922 
A system was developed to calculate the rate of adsorption of carbon-dioxide (124389) (CO2) on finely ground ferric-oxide (1309371) powder. The automated system which was used allowed the display of measurements on read out devices, a differential voltmeter, and an XY plotter. The parameters measured were power input to the heat of immersion colorimeter, temperature and pressure of sample areas of the balance system, and sample weight. The system was checked for accuracy prior to use with silica spheres and anatase. The adsorption/desorption isotherms for anatase were comparable to those previously obtained by the National Bureau of Standards, and the data from heat of immersion tests showed excellent reproducibility with the maximum deviation of 3.4 percent from the mean. Ferric-oxide was 99 percent pure with particles from 0.33 to 1.4 microns in diameter. Three isotherms were determined at temperatures of 23.8 to 24.9, 0.0 to 2.0, and minus 73.3 to minus 78.5 degrees-C with a water bath, ice bath, and a dry ice acetone bath, respectively. Test samples weighing 2.4370 grams each were baked under vacuum at approximately 252 degrees-C for 16 hours, held at a constant torr pressure for 1.5 hours, gassed incrementally with CO2 to a total pressure of 756.3 millimeters of mercury, and measured at each gas increment. The data was plotted as micrograms of CO2 adsorbed per square meter area as ordinate; and pressure/saturation pressure was plotted as abscissa. The absorption/desorption isotherm of CO2 or iron-oxide showed that the removal of adsorbed CO2 from finely ground ferric-oxide was a function of pressure and temperature. The authors conclude that the finely divided powder, even though nontoxic, can absorb gas from the atmosphere and then desorb it in the human lung.