Simplified methods for characterizing dynamic sorption of SVOCs on viscous particles

Abstract

Abstract Exposure to indoor and outdoor semi-volatile organic compounds (SVOCs) poses a significant threat to human health. The dynamic mass transfer of SVOCs between gas and particles, especially those containing high-viscosity organic matter, plays an important role in determining the behavior of indoor and outdoor SVOCs and their exposure risk to human health. In this study, four simplified methods are proposed to characterize the dynamic interaction of SVOCs between gas and particles based on an analytical solution of the mass transfer model. The methods entail neither complex series calculations nor solutions to transcendental equations to estimate the SVOC dynamic behavior between the gas and particle phases. Through analysis, the critical value of mass Fourier number, i.e., 0.18, and the critical values of mass Biot number, i.e., 0.1 and 20, are used to divide the ranges of application of the different methods into six zones. The results calculated demonstrate that the simplified methods are sufficiently accurate to estimate the saturation state of SVOCs in viscous particles with different organic species. Based on these methods, the internal SVOC distribution in the particles and the time to reach equilibrium are discussed. The results calculated for benzo[a]pyrene between the gas phase and different particles show that the viscosity of the organic species in the particles has a significant impact on the sorption saturation degree of the SVOCs. Thus, caution should be exercised when the equilibrium assumption is made for studying the interaction of SVOCs between gas and particle phases, especially in the case of particles comprising organic species of high viscosities.