Atmosphere chemical disinfection

Table 16.5 Atmospheric oxidation and chemical hydrolysis of selected antiseptics and disinfectants, estimated by AOPWIN and HYDROWIN from EPI Suite.

They are used for chemical synthesis, water and waste treatment, disinfection, neutralizations, and the like. They can also be produced in atmospheric photochemical reactions and as undesirable products, for example, in the combustion of fuels and industrial processes. The most important inorganic gases are ammonia, carbon oxides, nitrogen oxides, ozone and sulfur oxides. 

Runaway reactions were an underlying cause of other industrial accidents such as that which occurred in Seveso, Italy in 1976. The nearby chemical plant was producing 2,4,5-trichlorophenol, an intermediate for manufacturing of a medical disinfectant hexachlorophene. The runaway reaction of 1,2,4,5-tetrachlorobenzene with sodium hydroxide went out of control and resulted by an explosion and release into atmosphere of an unintended byproduct of this reaction, highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The nearby communities were thus exposed to TCDD. This accident triggered industrial environmental safety regulations passed by the European Community in 1982 and termed Seveso Directive. 

With the caveat that release of toxic ozone to the ambient atmosphere must be avoided (see Section 5.11.7), disinfection of water by ozonation is a virtually ideal example of green chemical practice. The only raw material is universally available air, which is free. Ozone is produced only where it is needed as it is needed, without by-products. The ozone does not persist in water, where it decomposes to elemental oxygen, and there is very little likelihood of producing harmful disinfection by-products with ozone. 

Apart from its irreplaceable role as a filter in the atmosphere, commercially, it can be used as an alternative to chlorine to disinfect water supplies and also to kill bacteria in hospital operating theaters. Organic chemists find it a useful reagent in chemical synthesis. 

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