Study of the resistances to transfer of gaseous pollutant between material and indoor air

Materials responsible for formaldehyde and volatile organic compound (VOC) emissions

“…Since VOCs emitted from building materials generally originate from inside the materials, the mass transfer within the materials is important in determining the emission rates and should be considered in modeling. Up to now, two kinds of diffusion models have been proposed, i.e., one-phase solid models (Little et al, 1994;Huang and Haghighat, 2002;Xu and Zhang, 2003;Deng and Kim, 2004), and multi-phase solid models (Lee et al, , 2006Haghighat et al, 2005;Blondeau et al, 2008;Marion et al, 2011). Multiphase solid models consider the porous structure of the material (pores and solid) and the mass transfer in both the pore-phase and the adsorbed-phase.…”

Assessment of steady state diffusion of volatile organic compounds in unsaturated building materials based on fractal diffusion model

“…The assumptions of this fractal model presented in this work are analogous to those proposed by Marion et al [3]: 1) surface and solid phase diffusions are negligible compared to air phase diffusion [6]; 2) Diffusion coefficient is constant in steady state condition; 3) adsorption/ desorption mechanism is not taken into account; and 4) no chemical reaction occurs between VOCs and building materials. Therefore, molecular diffusion coefficients of VOCs, D w and D g in Eqs.…”

“…Based on fractal features, these two fractal dimensions for pore tortuosity D tw and D tg in Eqs. (3) and (4) can be calculated from a serial of empirical equations below [38]:…”

“…Normally, volatile organic compounds (VOCs) produced from many building materials have vapor pressures greater than 0.1 mm of Hg at standard condition (20 C and 760 mm Hg) and are considered as the major sources resulting in poor indoor air quality, which is potentially dangerous to the health of human being [2e5]. One of the challenges in the utilization of building materials is to avoid the excessive emission of VOCs in indoor environment [3,4].…”

Modeling Ozone Removal to Indoor Materials, Including the Effects of Porosity, Pore Diameter, and Thickness

“…Activated carbon is known to adsorb pollutants like VOCs and react with ozone, 23,24 porous filters are used to remove particulate matter from air, 25 and porous zeolites can act as a catalyst for the oxidation of VOCs in the presence of an oxidizer like ozone. 26 Fundamental models describing the transport of pollutants in materials exist 27,28 and can address porous diffusion and adsorption/desorption processes (e.g., Marion et al 29 ). However, these models generally aim to describe indoor materials as sources or sinks of volatile organic compounds (VOCs) or semivolatile organic compounds (SVOCs).…”