COMPOSITION AND TEMPERATURE-DEPENDENCE OF THE DELIQUESCENCE PROPERTIES OF HYGROSCOPIC AEROSOLS

Thermodynamic considerations are given to the hygroscopicity of inorganic salts comprising most of the ambient aerosols. Equations are derived expressing the deliquescence humidity as a function of composition and temperature for either single-salt or multicomponent aerosols. Experimental results obtained with charged salt particles individually suspended in an electrodynamic cell are compared both with theory and with available literature data on relative humidities over saturated aqueous solutions. The good agreement found between theory and experimental measurements indicates that aerosol deliquescence properties are predictable from the principle of solution thermodynamics. Furthermore, the experimental technique described here is ideally suited for providing data for complex aerosol systems about which no information is yet available.