Purification/deodorization of indoor air and gaseous effluents by TiO2 photocatalysis

Our objective was to further assess the capabilities of TiO2 to purify/deodorize indoor air and industrial gaseous effluents. Using a laboratory photoreactor including a lamp emitting around 365 nm and a TiO2-coated fiber glass mesh, we first determined that the removal rate of three very different pollutants (CO, n-octane, pyridine) was 5-10 mu mol per Wh consumed by the lamp for 50-2000 ppmv concentrations and 25-50 1 h(-1) flow rates (dry air or O-2). We inferred that this order of magnitude allows, by use of a reasonable-size apparatus, the abatement of pollutants in constantly renewed indoor air, except CO and CH4 that are too concentrated. Using a TiO2 photocatalysis-based individual air purifier prototype, we showed, through distinctive analytical measurements, that the average concentrations of benzene, toluene and xylenes were indeed reduced by a factor of 2-3 in an ordinary non-airtight room. We also showed that O-3 addition in O-2 very markedly increases the mineralization percentage of n-octane, under otherwise identical conditions, in the laboratory photoreactor without photoexcitation of O-3; this property of O-3 can expand the application field of photocatalytic air purification in industry, at least in some cases. (C) 2000 Elsevier Science B.V. All rights reserved.