Harmful gases removal

Usually improvement combustion processing or after combustion treatment are used nowadays for NO reduction. However, they are some problems as like a complex, expensive setup, harmness gas emission, and corrosion metal. In recent years, to overcome these problems, some researchers have reported that NO is reduced more effectively use of the adsorption characteristics of activated carbons (ACs) and activated carbon fibers (ACFs) [6-8]. Also, some researchers are studying for NO reduction using metal supported ACs and ACFs by impregnation, metal plating, deposition, and so on [9-13]. However, metal supporting methods on ACs and ACFs in a second and their NO removal efficiency are not studied yet systematically. 

The content to follow will be presented in the order of CO2 capture, acid-gas removal, VOC adsorption, and radioactive gas adsorption in MOFs, as we described above. The intention is not to present a complete review and summary on all the related research published in the literature, but to try giving a flavor of the research in which MOFs are used to adsorb these harmful gases and share... 

In summary, MOFs are promising novel adsorbents for harmful gas separation and removal. Tremendous research work has been done on improving the performance of MOFs, such as adsorption capacity and selectivity. As we mentioned above, with respect to... 

If the water is gas lifted to the surface, separation facilities will be required. Typically, a simple two-phase separator is sufficient, since small levels of dissolved natural gas in the water are not harmful to the equipment or the injection formation. If the gas used to lift the water contains acid gases or oxygen, then some treating may be necessary to remove or neutralize these harmful gas components. 

The oxidation of CO over perovskite oxides has been largely investigated not only with the aim for removing this harmful gas, but also for using as a probe reaction to study the defect chemistry of these compounds. The first report using perovskite oxides as catalyst for CO oxidation was carried out by Parravano in the early 50s, [58] while it is still extensively investigated up to date. 

Fouling Industrial streams may contain condensable or reactive components which may coat, solvate, fill the free volume, or react with the membrane. Gases compressed by an oil-lubricated compressor may contain oil, or may be at the water dew point. Materials that will coat or harm the membrane must be removed before the gas is treated. Most membranes require removal of compressor oil. The extremely permeable poly(trimethylsilylpropyne) may not become a practical membrane because it loses its permeability rapidly. Part of the problem is pore collapse, but it seems extremely sensitive to contamination even by diffusion pump oil and gaskets [Robeson, op. cit., (1994)]. 

Hydrogen chloride [7647-01-0] M 36.5. Passed through cone H2SO4, then over activated charcoal and silica gel. Fumes in moist air. Hydrogen chloride in gas cylinder include ethylene, 1,1-dichloroethane and ethyl chloride. The latter two may be removed by fractionating the HCl through a trap cooled to -112°. Ethylene is difficult to remove. Fumes in moist air. HARMFUL VAPOURS. 

Hydrogen iodide (anhydrous) [10034-85-2] M 127.9, b -35.5°. After removal of free iodine from aqueous HI, the solution is frozen, then covered with P2O5 and allowed to melt under vacuum. The gas evolved is dried by passage through P2O5 on glass wool. It can be freed from iodine contamination by repeated fractional distillation at low temperatures. Fumes in moist air. HARMFUL VAPOURS. 

The dense fluid that exists above the critical temperature and pressure of a substance is called a supercritical fluid. It may be so dense that, although it is formally a gas, it is as dense as a liquid phase and can act as a solvent for liquids and solids. Supercritical carbon dioxide, for instance, can dissolve organic compounds. It is used to remove caffeine from coffee beans, to separate drugs from biological fluids for later analysis, and to extract perfumes from flowers and phytochemicals from herbs. The use of supercritical carbon dioxide avoids contamination with potentially harmful solvents and allows rapid extraction on account of the high mobility of the molecules through the fluid. Supercritical hydrocarbons are used to dissolve coal and separate it from ash, and they have been proposed for extracting oil from oil-rich tar sands. 

The small particles are reported to be very harmful for human health [98]. To remove particulate emissions from diesel engines, diesel particulate filters (DPF) are used. Filter systems can be metallic and ceramic with a large number of parallel channels. In applications to passenger cars, only ceramic filters are used. The channels in the filter are alternatively open and closed. Consequently, the exhaust gas is forced to flow through the porous walls of the honeycomb structure. The solid particles are deposited in the pores. Depending on the porosity of the filter material, these filters can attain filtration efficiencies up to 97%. The soot deposits in the particulate filter induce a steady rise in flow resistance. For this reason, the particulate filter must be regenerated at certain intervals, which can be achieved in the passive or active process [46]. 

Petroleum refining also produces substantial amounts of carbon dioxide, which with hydrogen sulfide, corrode refining equipment, harm catalysts, pollute the atmosphere, and prevent the use of hydrocarbon components in petrochemical manufacture. When the amount of hydrogen sulfide is high, it may be removed from a gas stream and converted to sulfur or sulfuric acid. Some natural gases contain sufficient carbon dioxide to warrant recovery as dry ice. 

Fuel processing is defined in this Handbook as the conversion of a commercially available gas, liquid, or solid fuel (raw fuel) to a fuel gas reformate suitable for the fuel cell anode reaction. Fuel processing encompasses the cleaning and removal of harmful species in the raw fuel, the conversion of the raw fuel to the fuel gas reformate, and downstream processing to alter the fuel gas reformate according to specific fuel cell requirements. Examples of these processes are ... 

Removal and mobilization of exploded and unexploded ordnance (including fired shells containing nerve gas or other harmful chemicals)... 

According to the Westinghouse Savannah River Company, in situ bioremediation with natural gas injection quickly degrades and removes contaminants, is cost effective, produces no harmful side effects, and may be applicable to benzene, toluene, and other biodegradable organics where cleanup levels of less than 10 ppm are required. 

The flue gas from municipal waste incinerator boilers contains SO2, and HCl. To remove these harmful components simultaneously by dry process, electron beam treatment method was investigated. The pilot-scale test was conducted in Matsudo, Japan, in 1992 with a flue gas of 1000 m /hr [34]. Recently, dioxins, namely, poly-chlorinated-di-benzo-paradioxins (PCDDs) and poly-chrorinated-di-benzo-furan (PCDFs), from incinerators have become a very serious problem because of their high toxicity. Pilot-scale tests to decompose dioxins by electron beam irradiation were conducted in Karlsruhe, Germany [35], and in Takahama, Japan [36], using almost the same capacity of flue gas, 1000 m /hr. Very promising results were obtained with decomposing more than 90% of dioxins. 

One important application of electrolytic treatment is the removal of harmful anions, such as chloride and sulphide, from the mineralized archaeological artifacts. The negative polarization of the system repels the negatively charged species out of the cathode. The process is often accompanied by the formation of either gas or soluble species in the electrolyte. This kind of treatment was carried out to increase the rate of extraction of chlorides from iron (see Fig. 6.1) [295], copper [296], and aluminium [297] mineralized objects. 

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