Separation of gases

The adsorption of water, hydro carbons and other liquid molecules from the gas streams can be carried by employing zeolites absorption characteristics. Zeolite 3A, 4A, 5A and 13X have been characterized for their application as adsorbents and desiccators [30]. These zeolites have also been found to have potential applications as molecular sieves in gas purification technology [31]. 

Flue gas treatment can occur by application of zeolite X (pores 7.3 A), Na-Pl, Na-Chabazite, Philipsite-KM, Linde F, Analcime, Sodalite and blend of zeolites 4A and X, which have been investigated to have different CEC and adsorption capacity for separation of CO2, SO2, H2O and NH3 from low water (i.e., the lowest level of water in a body of water such as river, lake, reservoir and well) gaseous emissions which can be attributed to their surface pore sizes as depicted in Fig. 7.5 [25, 32]. 

Most separation processes are carried out at low pressures where the perfect gas law is assumed to hold. The entropy of a perfect gas is given by 

The symbols and are the entropy and enthalpy values at some reference state, respectively, and is the heat capacity at constant pressure. 

By substituting Eqs, (6.4) and (6.5) into Eq. (6.3) and noting that — T2 for an isothermal process, the ideal work of separation for a binary perfect gas mixture is 

Since the total volume of the system remains constant, the pressure ratios can be expressed in terms of the mass ratios as 

For a two-component mixture, the work requirement from Eqs. (6.6) and (6.8) per unit mole of mixture is given by 

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Graham showed that the rate of diffusion of different gases through a porous diaphragm was inversely proportional to the square roots of their densities this is the basis of a method of separation of gases, and has been applied successfully to the separation of hydrogen and deuterium. 

W. H. Whidock, "The Ultra-High Purity Chahenge", in Separation of Gases, Proceeding of the Fifth BOC Priestley Conference, Birmingham, U.K., Sept. 19—21,1989, Royal Society of Chemistry, 1990. 

W. H. Isalski, Separation of Gases, Clarendon Press, Oxford, 1989. 

H2—HD and Ar— Ar binary gas mixtures have been measured (34,35). A vortex tube has been used for isotope separation (36), and for the separation of gases in nuclear rocket or ramjet engines. 

E. RxX z m. Aerodynamic Separation of Gases and Isotopes, Eecture Series 1978, Von Karmen Institute for Fluid Dynamics, Belgium, 1978. 

Separation of gases and liquids always involves coalescence, but enhancement of the rate of co escence may be required only in difficult separations. 

Permeability Different plastics provide different permeability properties. As an example polyethylene will pass wintergreen, hydrocarbons, and many other chemicals. It is used in certain cases for the separation of gases since it will pass one and block another. Chlorotrifluoroethylene and vinyli-dene fluoride, vinylidene chloride, polypropylene, EVA, and phenoxy merit evaluation (Chapter 4, PACKAGING, Permeability). 

Craig, H., Horibe, Y. and Sowers, T. 1988. Gravitational separation of gases and isotopes in polar ice caps. Science 242,1675-1678. 

J. (1986) Mixed matrix membrane for separation of gases. US Patent 6,726,744. 

The advantage of the two-phase micro flow contacting concept is easy phase separation, as the phases are never inter-mixed. However, in view of the normally facile separation of gases and liquids, this is not of major impact. A real large benefit stems from operating with gas and liquid layers of defined geometry with a knovm, defined interface, unlike most disperse systems having a size distribution of their bubbles in the continuous liquid. 

Gases entrapped in pore spaces resulting from phase separation of gases from liquids can reduce the permeability of a formation. This process was the major cause of clogging at groundwater recharge... 

Here, attention will focus on physical adsorption. This is a commonly used method for the separation of gases, but is also used for the removal of small quantities of organic components from liquid streams. 

Isalski WH (1989) Separation of Gases, Oxford Science Publications. 

Molecular sieves are synthetic zeolites that can be manufactured with extremely close control of pore size. Therefore, they can be tailored to suit specific applications. In addition to gas drying applications, molecular sieves are used for the separation of gases and vapors on the basis of molecular size and shape. Surface areas range from 350 to 1000 ft2/ft3. 

GC is particularly useful in soil analysis because of both the wide variety of columns available for separating specific mixtures and because of the variety of very sensitive detectors available. There are specific columns for separation of gases commonly found in the soil atmosphere and specific columns for the analysis of herbicides, insecticides, and pollutants. 

Rayleigh, J. W. S. (1896). Theoretical considerations respecting the separation of gases by diffusion and similar processes. Phil. Mag., 42, 77-107. 

In the recent years, many researchers have devoted attention to the development of membrane science and technology. Different important types of membranes, such as these for nanofiltration, ultrafiltration, microfiltration, separation of gases and inorganic membranes, facilitated or liquid membranes, catalytic and conducting membranes, and their applications and processes, such as wastewater purification and bio-processing have been developed [303], In fact, almost 40 % of the sales from membrane production market are for purifying wastewaters. 

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