Penetration of gas

Parallel flow. The direction of gas flow is parallel to the surface of the sohds phase. Contacting is primarily at the interface between phases, with possibly some penetration of gas into the voids among the solids near the surface. The solids bed is usually in a static-condition (Fig. 12-30). 

Penetration of gas bubbles into the Luggin capillary can disturb the steady operation. In the worst case, the control circuit of the potentiostat will be interrupted and the cell current can increase... 

Figure 11 shows the SEM pictures of (a) the y-Al203 powder layer and (b) the screen-printed layer of the y-Al203 powder with the colloidal silica binder. Because the porous structure has space between particles the penetration of gas into the printed layer is allowed. 

We shall assume that there is no penetration of gas into the solid (i.e. no absorption) so that zone I is occupied solely by the adsorbent and therefore c = 0. In zone ID, the adsorbable gas is at sufficient distance from the solid surface to have a uniform concentration, c8, and here z > t. In this legion the concentration is dependent only on the equilibrium pressure and temperature. In Figure 2.1a, zone II is the adsorbed layer , which is an intermediate region confined within the limits z = 0 and z = f. Here, the local concentration, c, is higher than the concentration of the gas in zone HI and is dependent on z. 

On the energy supply side the early penetration of gas in the first half of the 1990s, the limited use of coal and the full exploitation of existing hydro power have resulted in an electricity generation system... 

The rapid rate of reaction of iron above 570 °C causes thick scales to develop quickly and, in spite of the relatively high plasticity of the FeO layer, scale-metal adhesion is lost and a porous inner layer of FeO is formed, next to the metal, by the mechanism described earlier. The stresses associated with rapidly growing scale undoubtedly induce physical defects in the outer scale and the penetration of gas molecules, especially those belonging to the CO-CO2 and H2-H2O redox systems, will play a role in scale formation. 

Apart from the variety of possible agent fills, there are several other reasons why unusual compounds might be present in recovered munitions. Special formulations of agents and industrial chemicals were sometimes used to achieve certain effects. For instance, tin tetrachloride was encountered in phosgene rounds treated in the Porton Down tests of the EDS-1. This chemical was added to facilitate the penetration of gas masks and to produce a smoke that aided in spotting where rounds had landed. Chlorobenzene, possibly used as a solvent or stabilizer, was found in the mustard rounds processed at Porton Down (Table 2-1). Chlorinated rubber was used as a thickener in some mustard formulations. In addition, unusual compounds or sludges may result from chemical reactions such as corrosion and polymerization that may occur among the components over a period of decades. 

The SrCe03- and BaCe03 based materials can be prepared as dense ceramics with moderate hardness, the colour of which is pale brownish-green except for the Nd-doped ones which are black. The porosity of the ceramics is less than 5%, without open pores to allow the penetration of gas. Dilatometric measurements on SrCe. 95Ybo, os03 a showed that the thermal expansion from room temperature to 1000 °C was about 1.0%. These ceramics are soluble in some mineral acids at room temperature, especially in concentrated hydrochloric acid liberating chlorine gas, while they do not dissolve in aqueous alkaline solution ... 

As is the case with fuel cells, depolarized cathodes have been considered for years but have not yet found wide commercial use in the chlor-alkali indusby. Reports of work in the 1970s and 1980s [117,118] described the use of solid-polymer electrolyte systems. Microporous electrodes are necessary for electrical continuity in these cells, and the cathode reaction takes place in the interior of the gas-diffiision electrode. Operating deficiencies include the gradual penetration of gas channels by caustic solution and the possibility of bulk flow of catholyte into the gas side of the electrodes. Section 17.2.2.2 describes more recent work that addresses these deficiencies. The first conunercial applications are beginning to appear. 

The penetration of gas molecules in the lattice (inside) structure of coal prove indirectly the fact that the monolayer equivalent surface are of coal depends on the temperature and on the molecular size of the sorptive gases [15]. In Figure 10 are shown these phenomena which can be explained by the inside structure of coal discussed in point 1.1. 

FIG U RE 4 (a) Penetration of gas molecules in a pure polymer matrix and (b) Tortuous pathway created by incorporation of nanocomposite on polymer matrix (Duncan, 2011). 

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