UBC Theses and Dissertations
The removal of smokes and mists Guthrie, David Alan
A colorimetric quantitative analysis for di-n-octylphthalate and other aromatic esters has been developed which is capable of determining as little as 0.1 milligrams of an ester. This method is based on the formation of hydroxamic acid from esters using hydroxylamine hydrochloride in an alkaline medium. On the addition of an acidified solution of ferric per-chlorate, a red-colored complex of ferric hydroxamate is formed, proportionate in intensity to the weight of ester present. Mist composed of di-n-octylphalate droplets of 0.869 microns average diameter was removed from air at substantially atmospheric temperature and pressure by passing the air up through a bed of 150/200 mesh silica gel fluidized in a 2-1/4 inch glass column. Removal efficiency, defined as the percent (by weight) removal of the mist was substantially independent of the entering concentration over the range 0.765 to 0.965 milligrams of ester per cubic foot of air. For a given bed, removal efficiency improved with decreasing superficial gas velocity. Two bed weights were used, 13.25 grams per square centimeter and 25.35 grams per square centimeter, and it was found that the removal efficiency was practically in dependent of the bed weights. The maximum removal efficiency was 88.8% at a superficial bed velocity of 3.2 centimeters per second and a bed weight of 13.25 grams per square centimeter. The same mist was removed by passing the gas stream through various venturi nozzles with ports in the throat through which fine silica gel (150/200 mesh) entered by gravity and aspiration into the gas stream. For the venturi nozzles the removal efficiency generally increased with increasing velocities; however, the maximum removal efficiency obtained was only about 40%. It is shown that the behavior and collection efficiences obtained with the two devices can be satisfactorily explained if the fluidized bed is assumed to collect the aerosol particles by diffusional processes only, and the venturi tube, by inertial processes only, at least for aerosol particles of the size used in this work. The problem of efficient removal of aerosol particles in the range of 0.1 to 1.0 microns diameter has still not been solved in an economical manner for many cases of industrial importance. The removal becomes even more difficult when the aerosol particles are fairly uniform in size. The purpose of the present work was to conduct a preliminary testing of new devices which might be more efficient for small particles than those now commonly used.
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