Gases chemical pollutant

The real-time monitoring of some species concentration distribution in indoor air is an effective way to evaluate the dispersion of fresh air and/or gas-phase chemical pollutants, for example when determining the ventilation effectiveness, the air exchange rate (ACH) or the air age distribution for a given space (Park et al., 1998 Shin et al., 2005). It also provides a helpful validation for transient... 

The objective of the present article is to introduce both basic and advanced realtime monitoring techniques to researchers or engineers in the field of indoor gas-phase chemical pollutant control. Each real-time monitoring technique is introduced according to a detection or measurement principle a measuring method selectivity, sensitivity and accuracy application illustrations. Examples of applying these real-time monitoring techniques are also presented. 

Many gas-phase chemical pollutants such as VOCs absorb IR light at specific wavelengths. When a broad spectrum of IR light is passed through a gas, some of the frequencies are absorbed while the rest are transmitted without being absorbed. Those frequencies absorbed correspond to the natural frequencies of the vibration modes of the gas molecules or to a harmonic of these vibrations. The amount of energy the gas molecules absorb is proportional to its concentration... 

Flue gas The air coming out of a chimney after combustion in the burner it is venting. Flue gas includes, nitrogen oxides, carbon oxides, water vapor, sulfur oxides, particles, and many chemical pollutants. 

The gas that you see coming from the towers of the Three Mile Island nuclear power plant in Pennsylvania is all water vapor. Few chemical pollutants are released during the normal operation of a nuclear plant. Both equipment failure and human error resulted in overheating of the reaction chamber and a partial meltdown of fuel rods at this power plant in 1979. As a result, the building surrounding the reactor became flooded with water contaminated with radioactive material, and radioactive gas was released into the atmosphere. ... 

End-of-pipe measures can fix the pollution problem, but do not remove its cause. Sometimes the problem is solved only apparently. From a systemic viewpoint, the solution might be even a disadvantage. For instance, acid-gas scrubbing may cut air pollution, but creates liquid or solid chemical pollution, without regarding the pollution associated with the manufacture of supplementary chemicals. 

Cerium-zirconium mixed metal oxides are used in conjunction with platinum group metals to reduce and eliminate pollutants in automotive emissions control catalyst systems. The ceria-zirconia promoter materials regulate the partial pressure of oxygen near the catalyst surface, thereby facilitating catalytic oxidation and reduction of gas phase pollutants. However, ceria-zirconia is particularly susceptible to chemical and physical deactivation through sulfur dioxide adsorption. The interaction of sulfur dioxide with ceria-zirconia model catalysts has been studied with Auger spectroscopy to develop fundamental information regarding the sulfur dioxide deactivation mechanism. 

Many chemical technologies that save lives or improve the quality of life in the short term have had a negative impact on the environment. Chemical pollution is often divided into gas, liquid, and solid waste materials. Additional technologies often exist remediate these effects and improve pollution. 

A process has been developed to separate carpet waste using a cold, dry abrasive step [55]. Dry ice pellets are shot into an abrasive zone as a segment of discarded carpet on a conveyor system is stripped apart and disassembled. The dry ice pellets freeze the binder material (usually latex), lowering it to a temperature that makes the binder brittle and easy to break apart. The dry ice pellets sublimate directly into gas without any liquid residues. This process eliminates the need for a drying operation, which saves energy and avoids potential chemical pollution. 

A.L. Hines and T.K. Ghosh, Water Vapor Uptake and Removal of Chemical Pollutants by Solid Adsorbents, Gas Research Institute, Chicago, IL, Report No. GRI- 92/0157.2, pp. 234, 1992, NTIS No. PB95-104691. 

Some contaminants in a gas stream are neither chemical pollutants nor objectionable particulates. They are malodorous materials that are considered a nuisance if vented into the atmosphere. The maximum desired atmospheric level of a malodorous substance is defined as that concentration just below the threshold of detection by 50% of an odor panel. Table 5-7 gives this detection limit for many common malodorous substances [10]. Note that many substances can be sensed by the olfactory nerves at levels below one part per billion. For instance, hydrogen sulfide can be detected to one fifth of one ppb, while butyric acid (the principal odor from rancid butter) can be detected to one half of one ppb. 

Applications. Alloy 255 is finding many cost-effective applications in the chemical, marine, metallurgical, municipal sanitation, plastics, oil and gas, petrochemical, pollution control, wet phosphoric acid, paper-making, and metal-working industries. 

The deposition processes described in this chapter can be separated into two categories dry and wet. Dry deposition refers to chemical deposited to the surface in association with depositing particles. Here, we deal primarily with deposition to flat surfaces with low surface roughness, such as bare soils and water. Chemical transport from the atmosphere to plants and within the canopy is covered in Chapter 7. Particle dry deposition velocities to vegetation may be considerably higher than deposition to flat surfaces. Wet deposition refers to chemical deposited to the surface in association with rain or snow. Rain and snow scavenge both particle-associated and gas-phase pollutants, thus we can further differentiate wet particle deposition and wet gaseous deposition. By their nature, wet deposition processes are episodic. 

Since the intracluster medium will become polluted by heavy elements because of the explosion of massive stars in the member galaxies, the amount of heavy elements in the cluster gas is a clue to the efficiency of this process, and an indirect clue to the heating mechanism. Recent observations with ROSAT and ASCA suggest that many observed clusters have lower than solar iron abundance, suggesting that chemical pollution by supernovae is not so important. However, spatially resolved X-ray spectra of galaxy cluster emission by ROSAT show that the central... 

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