Adsorption-type chemical filtration is essential in many indoor purification applications. However, these chemical filters are expensive and have a limited filter life after breakthrough of contaminants. With toluene and isopropanol (IPA) as model contaminants, this study investigates the breakthrough behaviors of adsorptive chemical filters and TiO 2-enhanced chemical filters with various configurations - a chemical filter containing TiO 2-preloaded activated carbon (Scenario A), a chemical filter preceded by a TiO 2-coated non-woven sheet (Scenario B), and a chemical filter pressed against a TiO 2-coated non-woven sheet (Scenario C). The photocatalytic performance of the TiO 2-coated non-woven sheet was evaluated using several key operating parameters such as air moisture (relative humidity), TiO 2 loading density, light intensity, and challenge concentrations of model contaminants. The generation and accumulation of oxidative intermediate products from photocatalysis of toluene and IPA were also examined. Additionally, the Yoon-Nelson breakthrough model was experimentally validated and applied to generate adsorption breakthrough curves of several hypothetical challenge concentrations. The breakthrough studies indicate that the life of the filter in Scenario C was markedly longer than those of filters in scenarios A and B, even when photocatalysts were de-activated as a result of benzaldehyde accumulation from toluene decomposition. By pressing the TiO 2-coated non-woven sheet against the front face of the chemical filter, TiO 2 particles in the non-woven sheet and activated carbon granules in the chemical filter comprised a quasi-homogeneous system, yielding synergistic effects that enhance the operating lifespan of a chemical filter via photocatalysis. ? 2011 Elsevier B.V. All rights reserved.
Relation:
Separation and Purification Technology 85 , pp. 101-111
