Showing papers in "Industrial & Engineering Chemistry in 1955"

Air Pollution Studies-Photochemical Oxidation of Sulfur Dioxide in Air

Abstract: The rate of the photochemical oxidation of sulfur dioxide in air was determined in the concentration range 5 to 30 p.p.M. The reaction was carried out in a lucite cylinder in which the reaction mixture was exposed to ultraviolet light in the range from 3650 to 2950 A. The sulfuric acid drops formed as a result of the reaction were collected by a microtechnique involving impaction on an indicator film. The reaction is first order with respect to sulfur dioxide, and the rate is unaffected by the humidity, the presence or absence of salt nuclei, or by the concentration of nitrogen dioxide, in the ranges studied. The rate in artificial sunlight was in the order of 0.68% per hour and the mass median diameter of the particles was 0.19 to 0.45 microns. A few measurements in natural sunlight indicated the reaction rate to be approximately 0.1% per hour. The gas phase oxidation of sulfur dioxide of naturally polluted atmospheres in natural sunlight would not be significant in effectively reducing the visibility, since it would require approximately 100 hours of intense noon sunlight to reduce the visibility to 1 mile. Other types of oxidation, such as the liquid phase reaction inmore » fog droplets, or a combination of gas phase and liquid phase reactions at high humidity, may be more effective in reducing the visibility. These are being investigated.« less