Thermodynamic modelling of aqueous aerosols containing electrolytes and dissolved organic compounds

A method for calculating the thermodynamic properties of soluble mixed inorganic/organic aerosols is proposed. It is based upon the use of existing models of inorganic (electrolyte) multicomponent solutions and water/organic mixtures in combination, together with simple thermodynamically consistent terms that express the effects of interactions between ions and organic molecules on the activities of all mixture components. The method is used to calculate the deliquescence properties of the following systems at 298.15 K: sodium chloride/sucrose/water, letovicite/2-butenedioic acid/water, and sodium chloride/butanoic acid/water. The effects of approximations in the ion-organic interaction terms are explored, and it is shown that the method can be used to model liquid/liquid phase separation in sodium chloride/butanoic acid/water mixtures. In this example, it is found that the phase separation results in total water uptake that differs little from that of pure sodium chloride. (C) 2001 Elsevier Science Ltd. All rights reserved.