Surface degassing

Injection involves supplying gas to a flowing liquid through a porous heat transfer surface or injecting similar fluid upstream of the heat transfer section. Surface degassing of liquids can produce enhancement similar to gas injection. Only single-phase flow is of interest. 

Additionally, calcination at 900°C can increase the crystallinity degree of alumina that can also influence the adsorption of electron-donor compounds. Notice that the first portion of adsorbates (especially water) can dissociatively adsorb onto strained bonds appearing at the oxide surface degassed at high temperatures. 

This principle is illustrated in Figure 10 (45). Water adsorption at low pressures is markedly reduced on a poly(vinyhdene chloride)-based activated carbon after removal of surface oxygenated groups by degassing at 1000°C. Following this treatment, water adsorption is dominated by capillary condensation in mesopores, and the si2e of the adsorption-desorption hysteresis loop increases, because the pore volume previously occupied by water at the lower pressures now remains empty until the water pressure reaches pressures 0.3 to 0.4 times the vapor pressure) at which capillary condensation can occur. 

Lithium is used in metallurgical operations for degassing and impurity removal (see Metallurgy). In copper (qv) refining, lithium metal reacts with hydrogen to form lithium hydride which subsequendy reacts, along with further lithium metal, with cuprous oxide to form copper and lithium hydroxide and lithium oxide. The lithium salts are then removed from the surface of the molten copper. 

In the deaeration of high-viscosity fluids such as polymers, the material is flowed in thin sheets along solid surfaces. Vacuum is apphed to increase bubble size and hasten separation. The Versator (Cornell Machine Co.) degasses viscous liquids by spreading them... 

The effect of the mobile-phase composition on the operation of the different interfaces is an important consideration which will be discussed in the appropriate chapter of this book but mobile-phase parameters which affect the operation of the interface include its boiling point, surface tension and conductivity. The importance of degassing solvents to prevent the formation of bubbles within the LC-MS interface must be stressed. 

Radon is a noble gas and is therefore not readily ionized or chemically reactive. Its properties in terrestrial material will be controlled by its solubility in melt and fluid as well as its diffusion coefficients. Compared with the lighter noble gases, Rn diffuses more slowly and has a lower solubility in water. It will also more readily adsorb onto surface that the lighter rare gases. It can, however be lost by degassing in magmatic systems (Condomines et al. 2003). More information about the behavior of Rn can be found in Ivanovich and Harmon (1992). 

Flower shaped crystalline deposit on the surface of the solid non-crystalline mass of platinum sulphide was probably due to the precipitation of elemental sulphur, which deposited as a floral growth on the non-crystalline platinum sulphide precipitate. Ultrasonic irradiation seemed to have broken tender sulphur flakes and cleaned the surface. The free sulphur, however, did not deposit further. This was probably due to the formation of other compounds of sulphur such as H2S, S02, etc. which could have been removed from the solution due to the phenomenon of degassing. 

The linking agent, A3 or A4, was mixed in various concentrations with the divinyl-PDMS, together with 5 ppm of a Pt catalyst (8). The mixture was then degassed and cast as a thin sheet on a Teflon surface. Complete reaction was found to occur on heating... 

The products were collected after 6 hr reaction at room temperature. The total pressure was 300 mm Hg. Gaseous products were obtained by condensing the gas phase in a liquid nitrogen trap. Surface product was the strongly adsorbed propylene obtained by degassing at 125°C. 

Figure 22 shows the spectrum in the OH region for zinc oxide after admission of butene-1 at a pressure of about 8 mm (14). Spectrum (a), taken after 8 min exposures, shows two features (1) the strong surface hydroxyl band at 3615 cm-1 is shifted about 5 cm-1 to lower frequencies (2) a new band appears at 3587 cm-1. This new band, clearly an OH, appears to arise from dissociation of the adsorbed butene. Spectrum (b) shows the same region after exposure to the gas phase for 1 hr. It is clear that the OH band formed from butene grows with time detailed studies, however, reveal that there is little change after the first 20 min. Spectrum (c) was taken after 20 min evacuation. Two features are evident (1) in the absence of the gas phase the hydroxyl band of the zinc oxide has shifted back to its previous position (2) the OH band formed from butene is reduced somewhat in intensity. Spectrum (d) was taken after degassing for 90 min ... 

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