Heterogeneous photocatalysis: State of the art and present applications

In the present paper, the basic fundamentals of photocatalysis are explained with the influence of the five main parameters which govern the kinetics: (i) mass of catalyst, (ii) wavelength, (iii) partial pression and/or concentrations of reactants, (iv) temperature ( at a second degree) and ( v) the radiant flux. The main types of photocatalytic reactions presently described ( all performed at room temperature) concern ( i) the selective mild oxidation of hydrocarbons, ( ii) the hydrogen production and ( iii) the total oxidation reactions of organics in presence of water. The last point constitutes the ensemble of the last recent developments in photocatalysis. Most of organic contaminants, including dangerous pesticides, can be easily totally degraded and mineralized. Dyes are also not only decolorized, but mineralized in colored aqueous effluents. The most abundant ones ( the azo-dyes) have their azo-group(s) -N=N- decomposed into N2(g), which represents an ideal decontamination case. Photocatalytic engineering is under development, now using deposited titania in a fixed bed. Some ( solar) photocatalytic pilot reactors and prototypes are described. The use of solar energy as a source of activating UV - A irradiation is described as a sub-discipline called "helio-photocatalysis''.