Heterogeneous Photocatalysis for Control of Volatile Organic Compounds in Indoor Air.

Research results concerning the photocatalytic activity and selectivity of benzene are discussed. This compound, which represents one of an important class of volatile organic compounds found in indoor air, was oxidized in an annular photocatalytic reactor featuring a thin film of titanium dioxide and illuminated by a fluorescent black light. The gas phase products, carbon dioxide and carbon monoxide, were quantified with a Fourier transform infrared spectrometer (FTIR). Adsorbed intermediates were extracted from the surface with water. The extract was analyzed via high performance liquid chromatography and some of the adsorbed species were provisionally identified by retention time matching. The adsorption of reactants on the catalyst surface was studied explicitly, particularly with respect to the effect of near-UV radiation on adsorption processes. Maximum and steady-state rates of the surface reactions are reported here as functions of the operating conditions. Deactivation of the catalyst surface is characterized and methods of regeneration of catalyst activity are explored. This established research methodology provides the framework for a broader outline of research into enhancement of indoor air quality via photocatalytic oxidation. The results of investigations are discussed that pertain to a variety of classes of compounds representative of indoor air pollutants.