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2019
Conference Paper
Titel
A critical comparison of Junge/Pankow and Goss/Schwarzenbach theory
Titel Supplements
Abstract
Abstract
Understanding the partitioning of semi volatile organic compounds (SVOCs) between gas phase and particle phase is essential for exposure analysis and risk assessment in the indoor environment. Numerous attempts have been made to calculate gas/particle partitioning coefficients Kip. Single-parameter adsorption and absorption models, which relate Kip to the vapor pressure Ps (according to Junge and Pankow) or the octanol/air distribution coefficient KOA (according to Harner and Bidleman) are usually applied. However, the fact that single-parameter models do not take into account the specific intermolecular interactions that govern every sorption process and depend on the respective chemical structure of the molecules and the sorbing phase should be regarded as disadvantageous. In this work we used poly-parameter Linear Free Energy Relationships (pp-LFER) (according to Goss and Schwarzenbach) to describe the partitioning behavior of 14 SVOCs with high relevance for the indoor environment. The pp-LFER concept is based on Abraham descriptors and considers the size of the compound, interaction abilities like van der Waals, H-accepting (e-donating) and H-donating (e-accepting) as well as a dipolarity/polarizability parameter, which describes polar interactions that are not covered by the other parameters. Aerosol descriptors were taken from studies in ambient air. Therefore it was also necessary to evaluate the data set for indoor applications. Under the assumption that absorption into a water-insoluble organic matter (WIOM) phase is the dominating mechanism, the temperature dependence of the partitioning process could be described by the van't Hoff equation and the enthalpy for the distribution between air and WIOM. The results were compared with experimental and calculated Kip values from single-parameter models and the suitability of the pp-LFER method for indoor applications was critically discussed. It is shown that the pp-LFER method is a strong alternative to single-parameter approaches and gives reliable coefficients for gas/particle distribution in the indoor environment.