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

We develop an ozone transport and reaction model to determine reaction probabilities and assess the importance of physical properties such as porosity, pore diameter, and material thickness on reactive uptake of ozone to five materials. The one-dimensional model accounts for molecular diffusion from bulk air to the air–material interface, reaction at the interface, and diffusive transport and reaction through material pore volumes. Material-ozone reaction probabilities that account for internal transport and internal pore area, γ_ipa, are determined by a minimization of residuals between predicted and experimentally derived ozone concentrations. Values of γ_ipa are generally less than effective reaction probabilities (γ_eff) determined previously, likely because of the inclusion of diffusion into substrates and reaction with internal surface area (rather than the use of the horizontally projected external material areas). Estimates of γ_ipa average 1 × 10^–7, 2 × 10^–7, 4 × 10^–5, 2 × 10^–5, and 4 × 10^–7 for two types of cellulose paper, pervious pavement, Portland cement concrete, and an activated carbon cloth, respectively. The transport and reaction model developed here accounts for observed differences in ozone removal to varying thicknesses of the cellulose paper, and estimates a near constant γ_ipa as material thickness increases from 0.02 to 0.16 cm.