Modelling PUF passive air samplers: Temperature dependence of polyurethane foam e Air partitioning of PAHs and their O-, N-, and S-derivatives computed by COSMO-RS

Özet

The response of polyether-type polyurethane foam (PUF) passive samplers used to estimate the gaseousconcentration of organic chemicals has been modelled using the COSMO-RS methodology. Experimentaldata for equilibrium partitioning ratios were used to evaluate several different oligomers as surrogatesfor polyurethane foam over a temperature range of 15e95 C. Models were built with varying mole ratiosof mono- or di-isocyanates and ether-based linkers derived from glycerol, ethylene oxide, propyleneoxide, styrene and oligomers of ethylene oxide. Several models were found to have comparable rootmean-square (RMS) error, and COSMO-RS results were generally consistent with the empirical data. APUF model consisting of a 1:1 condensed pair of 2,4-toluene-diisocyanide and glycerol was found to haveminimal RMS error for both aromatic organic molecules and a large set of organic molecules studiedbetween 15 and 95 C. This model was applied to a series of simple and heteroatom-substituted polycyclic aromatics, for which the temperature dependence of air-polymer partitioning was predictedbetween 5 and 40 C. Log K(PUF-Air) is found to decrease by 1.5e2.5 log units over this range, reflectingthe increased volatility of the compounds with temperature, demonstrating the need for accurateexposure temperatures for partitioning involving air. The model results support the application of thepassive samplers for monitoring and research studies of polycyclic aromatic compounds (PACs) in air. Theapproach also illustrates an efficient strategy of selective acquisition of experimental data for COSMO-RSvalidation, coupled by theoretical prediction of a much larger number of chemicals at varioustemperatures.