Physically absorbed

A flow diagram for the system is shown in Figure 5. Feed gas is dried, and ammonia and sulfur compounds are removed to prevent the irreversible buildup of insoluble salts in the system. Water and soHds formed by trace ammonia and sulfur compounds are removed in the solvent maintenance section (96). The pretreated carbon monoxide feed gas enters the absorber where it is selectively absorbed by a countercurrent flow of solvent to form a carbon monoxide complex with the active copper salt. The carbon monoxide-rich solution flows from the bottom of the absorber to a flash vessel where physically absorbed gas species such as hydrogen, nitrogen, and methane are removed. The solution is then sent to the stripper where the carbon monoxide is released from the complex by heating and pressure reduction to about 0.15 MPa (1.5 atm). The solvent is stripped of residual carbon monoxide, heat-exchanged with the stripper feed, and pumped to the top of the absorber to complete the cycle. 

The carbon monoxide purity from the Cosorb process is very high because physically absorbed gases are removed from the solution prior to the low pressure stripping column. Furthermore, there is no potential for oxidation of absorbed carbon monoxide as ia the copper—Hquor process. These two factors lead to the production of very high purity carbon monoxide, 99+ %. Feed impurities exit with the hydrogen-rich tail gas therefore, the purity of this coproduct hydrogen stream depends on the impurity level ia the feed gas. 

The more highly complexed hydrates of calcium chloride (CaCl2 nH2 O where n > 2) may also exhibit the characteristics of a Class 2 dryiag agent, because the hydrated species can physically absorb additional water to form a saturated solution. The term absorption is used to describe the phenomenon that occurs when a gas or vapor penetrates the soHd stmcture to produce a saturated solution ... 

Several immersion treatments using solutions containing chromates have been developed for aluminium. It is not always clear to what extent the films formed can properly be called chromate films, i.e. films containing a substantial amount of a slightly soluble chromium chromate, but even if the film consists largely of aluminium oxide or hydroxide or other salt with chromate physically absorbed, it will still provide a reservoir of soluble chromate at the metal surface. Treatments fall into two classes alkaline and acid. The latter are of more recent development. 

An initial burst effect was observed in all in vivo studies. There are several possible factors which may cause a burst effect physically absorbed free drug, surface effects, and local tissue inflammation during the initial period of injection. It has been shown that inflammation decreases local tissue pH (15,16) and causes release of hydrolytic enzymes which would increase the hydrolysis of labile bonds, thereby increasing the release of the drug and, subsequently, increasing plasma levels of drug. 

An alternative approach aimed at reducing the segregation tendencies of medicaments and excipients involves milling the former to a small particle size and then physically absorbing it uniformly onto the surface of the larger particles of an excipient substrate. By these means ordered, as opposed to random, mixing is realized and dissolution is enhanced as a result of the fine dispersion [7]. 

The physical absorbents for acid gas removal from natural and synthetic gases. 

Chemical/Physical. Absorbs carbon dioxide forming carbonates (Patnaik, 1992 Windholz et al.,... 

Cellulose (VIII) is spun into fiber or cast into film by using a chemical reaction to convert it into a soluble xanthate derivative (Turbak, 1988). This is achieved by treating cellulose with 18-20% aqueous sodium hydroxide solution at 25-30°C for about 0.5-1 h. Much of the sodium hydroxide is physically absorbed into the swollen polymer some of it may be in the form of cellulose alkoxides. The excess alkali is pressed out of the cellulose pulp and the mass aged to allow oxidative degradation of the polymer chains to the desired molecular weight. The alkali cellulose is then treated with carbon disulfide at about 30° C and the resulting mass dissolved in dilute sodium hydroxide to form the sodium... 

The biologically weighted dose is a quantity intended to be correlated, as closely as possible, to the relevant biological/clinical effect. However, in all radiotherapy reports, the (physical) absorbed doses D and the biological weighting factors W jp, Rhdr, II pdr> IErbe, etc.) should always be indicated separately and not just the biologically weighted doses Dajp, T>hdr, -Dpdr, -Drbe, etc.). 

Figure 25 Treatment of a tumor of the base of skull with a carbon-ion beam. Comparison of the (physical) absorbed dose and of the biological dose (i.e., the dose weighted for the RBE variation in the carbon beam). The treatment is carefully planned in order to obtain a homogeneous biological dose to the PTV. For the same biological dose to the PTV, the normal tissues in the initial plateau receive a lower dose. (From Ref. 45.)...

However, in this context CPSs are defined throughout this article as very stable phy-sisorbed (physically absorbed) and/or most often covalently bound chiral selector compounds to a nonchiral (most often silica) surface. To the same category belong the CSPs, which have as their bases beads of polymeric chiral selector material. The strong irreversible adsorption of chiral selector molecules (macromolecules or small molecules onto a plain or premodified surface) depends, of course, on the nature of the mobile phase and whether or not it has some solvation strength for the adsorbed chiral selector moiety. 

Most of the CO2 that is physically absorbed by blood becomes H2CO3 by the above-mentioned reaction (A), in the presence of carbonic anhydrase. Thus, [H2CO3] is practically equal to [CO2], which should be proportional to the partial pressure of CO, that is,/)CO2. 

Extremely interesting infrared studies of physically adsorbed molecules were carried out by Sheppard and Yates (52). These workers studied the spectra of methane, ethylene, acetylene, and hydrogen on porous glass. They found that the perturbing effects of surface forces made it possible to detect bands which are found in the Raman spectra but are not observed in the normal infrared spectra. This indicates that the degree of symmetry of the adsorbed molecule is less than in the gaseous state because of the one-sided nature of the surface forces. This effect was discovered independently by Karagounis and Peter (52a) in studies 1,3,5-trichlorobenzene physically absorbed on silica. 

For quite a number of physically absorbed gases, Henry s law holds very well when the partial pressure of the solute is less than about 101 kPa (1 atm). For partial pressures above 101 kPa, H may be independent of the partial pressure (Fig. 14-1), but this needs to be verified for the particular system of interest. The variation of H with temperature is a strongly nonlinear function of temperature as discussed by Poling, Prausnitz, and O Connell (The Properties of Gases and Liquids, 5th ed., McGraw-Hill, New York, 2000). Consultation of this reference is recommended when temperature and pressure extrapolations of Henry s law data are needed. 

The "Inkjet Substrate" approach to enhancing print quality was characterized by a thin, highly absorptive layer, which physically absorbs... 

In our experiment, the compression strength of supports was tested by an intellect strength tester (Model ZQJ, China). Specific areas, pore volume and average pore diameters were measured by a static physical absorber (Model ASAP-2000, America). The surface of catalyst was observed under an electron microscope (Model JEM-1200EX). The crystal structure was detected by an X-ray fluorescence spectrometer (Model 3015, Japan). The content of Ru was detected by a plasma spectrum instrument (Model ICPS-IOOOII). 

The influence of physically absorbed water molecules on the methylene chloride adsorption and interaction capacity of silica will now be investigated. We generated, at 30 °C, three carrier gases having controlled percentages of moisture (RH%). The silica samples were equilibrated for several hours with these wet gases in order to achieve a constant yield of physically absorbed water. The... 

R. McIntosh, Dielectric Behavior of Physically Absorbed Gases, Marcel Dekker, New York, 1966. 

Figure 6.20. Stability of grafted carbon black (A), carbon black with physically absorbed polymer (B) and untreated carbon black (C). [Adapted, by permission, from Tsubokawa N, Hosoya M, Kurumada J, Reactive Functional Polym., 11, No.l, 1995, 75-81.]...

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