Porous Materials in Indoor Environments: Investigating Transport and Reaction Mechanisms of Pollutant Removal to Porous Indoor SurfacesEPA Grant Number: FP917330
Title: Porous Materials in Indoor Environments: Investigating Transport and Reaction Mechanisms of Pollutant Removal to Porous Indoor Surfaces
Investigators: Gall, Elliott T
Institution: The University of Texas at Austin
EPA Project Officer: Hahn, Intaek
Project Period: August 1, 2011 through July 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Science & Technology for Sustainability: Green Engineering/Building/Chemical Products & Processes/Materials Development
Human exposure to air pollutants is dominated by what is breathed indoors, and indoor materials can act as important sources and sinks of pollutants. This research investigates the potential for utilizing the large surface area of materials to remove indoor air pollution through reactive uptake processes. This research project will build on this idea by focusing investigations on porous materials, which can increase the surface area of the indoor environment by orders of magnitude, and may act as significant long-term sinks of indoor air pollution.
This work will investigate and characterize heterogeneous ozone chemistry with indoor surfaces, specifically pertaining to the determination of opportunities for increasing indoor ozone removal to surfaces. This will be accomplished by characterizing fundamental physical and chemical parameters, which will allow for more accurate modeling of ozone removal to porous building materials. The effect of physical properties like porosity, material thickness and material contamination on overall ozone removal will be determined using an experimental apparatus constructed for the project. With this information, a fundamental transport and reaction model will be developed and validated with chamber ozone concentrations measured. A sensitivity analysis will be performed to determine which material parameters have an outsized effect on overall ozone removal. The relative importance of fluid mechanic conditions and material properties will be assessed for whole-house modeling of ozone concentrations under a variety of airflow and indoor material scenarios.
The information determined in this investigation will result in a more detailed understanding of the mass transfer and transformation processes occurring during reactive removal of ozone with indoor surfaces. The determination of effective surface areas and porous diffusion time scales through indoor materials may help resolve disagreement between established mass-transfer models and experimental data, as well as comparisons across studies. This also will allow predictive modeling, which can more accurately assess the benefit of changing physical parameters of indoor materials, such as an increase in material thickness or porosity. Furthermore, the determination of the dependency of ozone removal on specific material parameters will aid in the theoretical design and/or fabrication of dedicated indoor pollutant removing materials.
Potential to Further Environmental / Human Health Protection
Reducing indoor ozone concentrations is important because 120,000,000 Americans live in ozone non-attainment areas, and with people spending 90 percent of their time indoors, a large portion of exposure to ozone occurs indoors. Targeting remediation of indoor environments with pollutant removing materials also will allow specific sub-populations to utilize passive removal in particularly efficient ways. Sensitive populations, to whom EPA’s outdoor ozone standards are intended to protect, may utilize specific materials to reduce trigger pollutants like ozone. Furthermore, pollutant removing materials investigated in this research can purify air with no direct energy inputs, improving indoor air quality without increasing the already substantial energy burden of buildings.