TiO2 photocatalysis for the abatement of ubiquitous indoor pollutants : study of the simultaneous degradation of aldehydes

In industrialized countries, people spend more than 20 hours a day indoors, being constantly exposed to several pollutants. Among the various pollutant molecules found in closed environments, aldehydes are the most prevalent and, specific attention is given to formaldehyde as a carcinogenic compound and as a ubiquitous substance, because of the large number of sources from which it is released. Photocatalysis was studied here in particular for the reduction of indoor air contaminants; specifically, we investigated the performances of three commercial powdered TiO2, two nano-sized and one micro-sized, for the photodegradation of formaldehyde alone, and in a gaseous mixture of aldehydes, taking into consideration the most recent studies of indoor pollutants. The first purpose of this study was to prove the effectiveness of TiO2 on formaldehyde, even when its particles are micro-sized; secondly, the study was directed to the photodegradation reactions of many aldehydes, with specific attention to the fact that they were degraded simultaneously, in a context much closer to reality, but still poorly studied. For this reason photodegradation was monitored by PTR-ToF-MS (Proton Transfer Reaction-Time of Flight-Mass Spectrometer), which is able to detect several molecules without any difficulty or interference.