Smog, removal

Smog Formation. In Chapter 1. Problem PI-14. in the CD-ROM Sr, Web Module, we discussed a very simple model for smog removal in Ihe 1 basin by a Santa Ana wind. We will now look a little deeper into the chemi of smog formation. Nitrogen and oxygen react to form nitric oxide in the inder of automobile engine.s. The NO from automobile exhaust is oxidizei NOi in the presence of peroxide radicals. 

Reduction of metal oxides with hydrogen is of interest in the metals refining industry (94,95) (see Metallurgy). Hydrogen is also used to reduce sulfites to sulfides in one step in the removal of SO2 pollutants (see Airpollution) (96). Hydrogen reacts directiy with SO2 under catalytic conditions to produce elemental sulfur and H2S (97—98). Under certain conditions, hydrogen reacts with nitric oxide, an atmospheric poUutant and contributor to photochemical smog, to produce N2 ... 

Fig. 7-12 Schematic of an atmospheric aerosol size distribution. This shows the three mass modes, the main sources of mass for each mode, and the principal processes involved in inserting mass into and removing mass from each mode (m = mass concentration. Dp = particle diameter). (Reproduced with permission from K. T. Whitby and G. M. Sverdrup (1983). California aerosols their physical and chemical characteristics. In "The Character and Origin of Smog Aerosols" (G. M. Hidy, P. K. Mueller, D. Grosjean, B. R. Appel, and J. J. Wesolowski, eds), p. 483, John Wiley, New York.)...

S02 and NOx in flue gas from coal combustion contribute to smog and acid rain. Methods to remove these pollutants include alkaline wet scrubber systems that fix S02 to solid CaS04, and selective catalytic reduction by metal/metal oxide systems of NO/NOz to N2 and steam in the presence of ammonia. Particulate active carbons have also been used in flue gas decontamination, especially as they avoid costly scrubber processes and can operate at lower temperatures. The potential of active carbon fibers in this application has been explored by a... 

Gas Cleaning and Purification. Gas cleaning means the removal of impurities existing in the form of suspended liquid or solid particles, such as vapors, mist, fog, smog, smoke or dust. The impurities might also include gaseous substances that are objectionable or obnoxious, and their removal is usually called purification... 

The removal of oxides of nitrogen is important because they cause respiratory disease. They are also involved in the production of photochemical smogs (Figure 7.16) which occur worldwide in major cities, especially in the summer. It should be... 

Atmospheric pollution caused by SO compounds from the combustion of fossil fuels, O3, CO2, volumetric CH compounds, and NO has become as matter of growing world wide concern in recent years. Nitrogen oxides contribute to acid rain and photochemical smog, and they can cause respiratory problem. Therefore, nitrogen oxides should be controlled and removed from the source in order to keep the earth clean and as-received for our health [1-3]. 

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