The Contamination of Fluorocarbon-Film Bags by Hydrocarbons and Nitrogen Oxides

Abstract

Experiments were conducted to investigate the appearance of contaminants in fluorocarbon-film bags which have been widely used as photochemical reactors and storage containers in air pollution research. Clean air stored in such bags was gradually contaminated by a wide range of heavy hydrocarbons (≥ C₅ ) as well as by nitrogen oxides. Warming a bag dramatically increased the contamination rate for hydrocarbons. The substances observed in the bags appear to have originated in the air outside the bags and appeared in the bags due to the permeability of the film. When a bag was stored in a controlled clean environment, the rate of contamination by hydrocarbons was dramatically reduced. Experiments in which high concentration mixtures of hydrocarbons and nitrogen oxides were stored in the bags likewise showed that some high molecular weight hydrocarbons as well as NO and NO₂ permeate through the bag walls. Decontamination of the bags can be accomplished by storing them in a clean environment.