Air treatment by photocatalytic processes

The emission of volatile organic compounds (VOCs) into ambient air has become a major public health issue in recent years. Numerous studies have shown that VOCs can be toxic, even carcinogenic, mutagenic or teratogenic. In addition to their direct effects on health, many compounds have very low odor thresholds and cause a major nuisance, both for site employees and neighbors. Their impact on the natural environment and on human health is therefore considerable . What's more, the growth of the human population and the creation of large cities have created new, more sedentary urban lifestyles, forcing people to expose themselves to a new type of atmospheric pollution: that linked to indoor air. Indeed, depending on climatic conditions, outdoor air is dispersed and washed by rain on a daily basis, whereas this is not the case for indoor air. This explains why most scientific research shows that the number and concentration of pollutants are much higher in indoor air than in outdoor air.

The problem of eliminating olfactory nuisance is a complex one, since the principle often lies in the treatment of a high-flow, low-load effluent, made up of a complex mixture of compounds, each of which contributes to the odorous "hue" .

The main families involved are sulfur derivatives (hydrogen sulfide, mercaptans, sulfides), nitrogen derivatives (ammonia, amines) and oxygen derivatives (volatile fatty acids, alcohols, aldehydes, esters). This diversity implies the use, preferably, of less selective depollution techniques, such as photocatalysis. Among the various processes that can be envisaged, it offers the advantage of requiring no reagents and generating as residue only the by-products of pollutant degradation, degradation that can be taken as far as mineralization (formation of CO ₂ and H ₂ O)