Water Absorption by Organics: Survey of Laboratory Evidence and Evaluation of UNIFAC for Estimating Water Activity

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• 作者：Pradeep Saxena and Lynn M. Hildemann
• 刊名：Environmental Science & Technology
• 出版年：1997
• 出版时间：November 1997
• 年：1997
• 卷：31
• 期：11
• 页码：3318 - 3324
• 全文大小：185K
• 年卷期：v.31,no.11(November 1997)
• ISSN：1520-5851

文摘

The composition of organic material in atmosphericparticlesand the influence of these organics on aggregate particleproperties have remained less well characterized thanthat of the inorganic ionic fraction. While laboratoryandatmospheric studies strive to quantify the formation ratesand concentrations of water-soluble and other organiccompounds in atmospheric particles, concerted effortsare being devoted by many scientists to develop models forsimulating the formation and gas-particle distribution ofcondensible organics in the atmosphere. Within thisresearchmilieu, as a first step toward developing a capability tosimulate the thermodynamics of aqueous, organic-containingsubmicron droplets under atmospheric conditions, in thispaper we (i) synthesize published laboratory data toevaluate the water absorption behavior of multifunctionaloxygenated organic compounds and (ii) test the reliabilityof the UNIFAC group contribution method (1) forestimatingwater activities of aqueous organic solutions. Thelaboratory data show that multifunctional oxygenatedcompounds can absorb water over the entire range ofrelative humidities. For a wide variety of compounds(e.g.,glycols, dicarboxylic acids, keto acids) and a wide rangeof solute concentrations (0 to >90% by wt), we find that,inmost cases, water activities can be estimated to withinapproximately 15%.