Photocatalysis, inorganic

One of the most important fields of application of photocatalysis is the photodegeneration of organic compounds. These processes are used in particular for environmental decontamination, especially for wastewater treatment and air purification, because of the ability of semiconductors to totally degrade organics to C02, H 20, and inorganic anions under U V or visible light. This behavior is attributed to the photoinduced formation of radicals, such as OH, or to the adsorption and direct degradation of the pollutants. 

Kalyanasundaram K, Graetzel M (eds) (1993) Photosensitization and photocatalysis using inorganic and organometallic compounds. Kluwer Academic Publishers, Netherlands... 

High-surface-area inorganic materials with ordered mesoporous structures have also been oT major interest Tor numerous applications including photocatalysis [99-102], The ultra-high-surface-area of mesoporous materials is appealing in applications of heterogeneous photocatalysis where it is desirable to minimize the distance between the site of photon absorption and electron-hole redox reactions to improve efficiency [103-105],... 

Titanium dioxide has also been involved in the photocatalysis of toxic inorganic substances to yield harmless or less-toxic species. Sterilisation of drinking water by chlorine yields potentially carcinogenic compounds so that ozone has been used as an alternative sterilising agent. Bromate... 

K. Kalyanasundaram and M. Gratzel (eds.). Photosensitization and Photocatalysis Using Inorganic and Organometallic Compounds. 1993... 

In addition to development of full laboratory courses, several individual experiments that can be included in such integrated laboratories have been developed recently. They include experiments on photocatalysis (148), synthesis, kinetics and thermodynamics of an inorganic compound (149), studies on conformational analysis (150), synthesis and variable temperature proton NMR of an inorganic compound (151), and the study of microemulsions (152). As such laboratories become more common, we can expect more of these experiments to appear in the literature. These integrated laboratory courses and experiments can be found in Table XL... 

The rate constants for reactions of OH with pollutants are summarized in Table 8.1. Rate constants can be used to estimate how easily a pollutant car. be treated by photocatalysis. N02 shows a higher rate constant with OH than any other inorganic compound in Table 8.1, while CH3SH, CH3CHO, propylene, m-xylene appear to be oxidized faster than other organic compounds. 

For the treatment of air and water, photocatalysis over Ti02 is a technique that is simple, robust, easily automated, and flexible. It is versatile because organic pollutants, some inorganic pollutants, and microorganisms can be eliminated or inactivated, respectively. In water, some ions can also be transformed. Its operating cost arises mainly from the UV lamps and the corresponding electrical consumption. Provided that the needs and location of the treatment allow it, this cost can be reduced substantially by the use of solar irradiation instead of UV lamps. For these reasons, photocatalytic water purification appears well adapted to isolated communities, in particular if no competent labor force is available. 

Serpone, N. Lawless, D. Terzian, R. Minero, C. Pelizzetti, E. Heterogeneous photocatalysis Photochemical conversion of inorganic substances in the environment Hydrogen sulfide, cyanides, and metals. In Photochemical Conversion and Storage of Solar Energy, E. Pelizzetti, M. Schiavello, eds., Kluwer Acad. Publ. Dordrecht, The Netherlands, 1991. 

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