Imbibition, gas

Keywords gas-solid reaction, acetone gas imbibition, inclusion compounds, desorption temperatures... 

Since the blocked gas inside of the capillary is dissolving in the liquid and then diffusing towards the exit of the channel, the meniscus of the liquid crosses the position l and goes deeper. This second stage of capillary filling with liquid is called diffusive imbibition and plays an important role in PT processes. The effect of diffusive imbibition upon PT sensitivity has been studied in [7]. 

At first we tried to explain the phenomenon on the base of the existence of the difference between the saturated vapor pressures above two menisci in dead-end capillary [12]. It results in the evaporation of a liquid from the meniscus of smaller curvature ( classical capillary imbibition) and the condensation of its vapor upon the meniscus of larger curvature originally existed due to capillary condensation. We worked out the mathematical description of both gas-vapor diffusion and evaporation-condensation processes in cone s channel. Solving the system of differential equations for evaporation-condensation processes, we ve derived the formula for the dependence of top s (or inner) liquid column growth on time. But the calculated curves for the kinetics of inner column s length are 1-2 orders of magnitude smaller than the experimental ones [12]. 

Interpretation for irreducible water saturation assumes that the rock is water-wet or mixed-wet (water-wet during drainage but the pore surfaces contacted by oil becomes oil-wet upon imbibition). If a porous medium is water-wet and a nonwetting fluid displaces the water (drainage), then the non-wetting fluid will first occupy the larger pores and will enter the smaller pores only as the capillary pressure is increased. This process is similar to the accumulation of oil or gas in the pore space of a reservoir. Thus it is of interest to estimate the irreducible water saturation that is retained by capillarity after the hydrocarbon accumulates in an oil or gas reservoir. The FFI is an estimate of the amount of potential hydrocarbon in... 

Our very first experiments with the reactor depicted in Figure 5.4.1 were carried out with a 15% Pt-Y-Al203 single cylindrical catalyst pellet [10-12], The acquisition time of 2D images of an axial slice at that time was about 260 s. Despite this, the first direct MRI visualization of the operation of a model gas-liquid-solid reactor has revealed the existence of large gradients of the liquid phase content within the catalyst pellet upon imbibition of liquid a-methylstyrene (AMS) under conditions... 

Nguyen et al. [205] designed a volume displacement technique that was used to measure the capillary pressures for both hydrophobic and hydrophilic materials. One requirement for this method is that the sample material must have enough pore volume to be able to measure the respective displaced volume. Basically, while the sample is filled wifh water and then drained, the volume of water displaced is recorded. In order for the water to be drained from fhe material, it is vital to keep the liquid pressure higher than the gas pressure (i.e., pressure difference is key). Once the sample is saturated, the liquid pressure can be reduced slightly in order for the water to drain. From these tests, plots of capillary pressure versus water saturation corresponding to both imbibitions and drainages can be determined. A similar method was presented by Koido, Furusawa, and Moriyama [206], except they studied only the liquid water imbibition with different diffusion layers. 

Table 2 Some results with gas- -solid imbibitions of acetone [28] ...

The first gas-solid imbibitions of chiral molecules by the host (S)-1,2-dihydroxy-1,1-diphenylpropane were not highly enantioselective [46] and can therefore not be discussed here. 

In the case of porous media, which are important in such fields as oil and gas recovery, soil remediation and catalysis, wettability determination requires somewhat different methods such as those based on the imbibition of liquids [157-159] ... 

To access the importance of Fg in Equation 53 and to determine how this quantity changes from non-dispersed flow to foam flow, a transient gas permeability test was performed and the results presented in Figure 11. In particular, drainage and imbibition tests were first conducted to reach a final drainage state with Ql being fixed at 0.53 pl/s. The measured permeability corresponded to the lower curve in Figure 11. Here again, the dependence on gas... 

Once such high gas saturations have been established, it is difficult to decrease these through liquid imbibition because of the breakup and trapping of the bubble trains once gas flow is stopped. If the gas flow is reinitiated, higher gas saturations can be realized however, the possible saturation changes in such dispersed flows are considerably smaller than those possible in non-dispersed flows. Further, the effects of flow rate or applied pressure drop on saturation are also small. 

In this section we shall briefly review some phenomena related to the penetration [imbibition] of porous solid materials by a liquid. These phenomena have great practical relevance. Numerous processes come to mind in which they play a role uptake of water in pharmaceutical powders, imbibition of dry soils by rain water, absorption of ink by paper, and tertleiry oil recovery. In the last example one fluid (mostly gas or aqueous) displaces the other (crude) and the process is therefore forced, in contradistinction to the other examples where penetration is spon-... 

For determination of the overall porosity, pycnometric methods are recommended that use imbibition of the material in a light inert gas and mercury. Mercury porosimetry is the method of choice for assessing macro- and meso-pores. The use of intrusion and extrusion measurements is necessary to understand more complex pore structures. 

Shrestha R, Noordermeer MA, van der Stelt M, Veldink GA, Chapman KD (2002) N-Acylethanolamines are metabolised by lipoxygenase and amidohydrolase in competing pathways during cottonseed imbibition. Plant Physiol 130 391-401... 

The ground host (2.00 mmol) was evacuated in a 250-mL flask that was connected at a vacuum line to a second 250-mL flask containing 2 mmol (for 4 3 mmol for 5 and 6 6 mmol) acetone. After 1 h at room temperature excess gas was condensed into flask 2 and the inclusion product evacuated for 1 h at 5 xlO 4 Torr. The table gives the molar ratio, the C=0 IR frequency of the included acetone, the desorption temperature (from TGA experiments), and the comparison with the molar ratio that was obtained from crystallization of the complex in liquid acetone. Below the imbibition ratios the acetone gas was completely taken up within detection limits. Exhaust gases required column flow systems for removal of acetone as an inclusion compound. 

References G. Kaupp, U. Pogodda, J. Schmeyers, Chem. Ber. 127, 2249 (1994) G. Kaupp, Top. Curr. Chem., 254, 95 (2005) there are also gas-solid imbibitions of hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, dichloromethane, furan, tetrahydrofuran, dioxane, methyl /-butyl ether, ethyl acetate, methanol, ethanol... 

Attempts have been made to determine why a-amylase synthesis eventually declines in the intact grain (e.g. see the decline in rate of a-amylase synthesis in Figure 7.4A and B after three and two days respectively). One possible reason is that production of the stimulus (i.e. GA) for a-amylase synthesis decreases, perhaps because hormonal synthesis is itself inhibited by the products of starch degradation. Unequivocal evidence supporting this possibility is lacking. In any case, sufficient gibberellin is released into the endosperm during the first one or two days after the start of imbibition to support a-amylase synthesis for at least four to five days thereafter (Fig. 7.4 C). Thus any limitation in GA synthesis after one or two days is unlikely to affect enzyme production. 

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