Environmental pollution Freon

The ECD and NIMS are important tools for the analysis of environmental pollutants. The determination of freon levels in the atmosphere and their effects on ozone depletion required the ECD. Identifying the highly toxic chlorinated dioxins was only possible with the ECD and NIMS. Despite these successes very little fundamental data for the reactions of electrons with these molecules in the gas phase have been obtained. This chapter evaluates the available data and presents new data. 

In addition, in many industrial practices, additional carbon dioxide or freon gas (a major sources of environmental pollution) may be introduced into the system as it cures. For rigid foams a low boiling liquid may be added to form additional bubbles. Appropriate catalysts and foam stabilizers or surfactants are added to control foam formation, cell size, and cure. The catalysts are either tin compounds or tertiary amines. The surfactants that are necessary to control the cell size are usually based on siloxanes. 

The supercritical fluid carbon dioxide, C02, is of particular interest This compound has a mild (31°C) critical temperature (Table 1) it is nonflammable, nontoxic, and, especially when used to replace freons and certain organic solvents, environmentally friendly. Moreover, it can be obtained from existing industrial processes without further contribution to the greenhouse effect (see Air pollution). Carbon dioxide is fairly miscible with a variety of organic solvents, and is readily recovered after processing owing to its high volatility. It is a small linear molecule and thus diffuses more quickly than... 

Another area of environmental concern is the products themselves. Petroleum refining in the last 10 years has been driven by requirements for the composition of gasoline and diesel fuel that are continuously changed by environmental demands. Such considerations will have even stronger impact in the future. There are similar problems in the chemical process industries. The search for an environmentally acceptable substitute for Freon is a prominent present example. Another problem is polyvinyl chloride (PVC), which causes difficulties in incinerators. The question is, should we continue to produce PVC or should we find a substitute that is easier to dispose of Can we modify polymers in such a way that they cause fewer problems of pollution than they cause now These are major challenges for the profession, in both academia and industry. 

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