Drying phase equilibria

Corg,phase is the concentration of the compound in a given organic phase at equilibrium with the concentration in the environmental medium (therefore the superscript ), and is expressed, for example, as (mol kg-1 dry phase)... 

The calculation of two-phase (hydrate and one other fluid phase) equilibrium is discussed in Section 4.5. The question, To what degree should hydrocarbon gas or liquid be dried in order to prevent hydrate formation is addressed through these equilibria. Another question addressed in Section 4.5 is, What mixture solubility in water is needed to form hydrates ... 

At adiabatic saturation temperature Ha, Ya lb/lb dry air Phase equilibrium ratio Relative distribution of two components K K = y x... 

The column operable range is determined in part by the requirement that no tray be allowed to dry up, that is, liquid and vapor must exist on each tray to maintain phase equilibrium. This range may be defined by the limits over which the condenser and reboiler duties may vary. As such, the condenser and reboiler duties are considered the two independent variables required to define the column performance (Sections 3.2.3 and 5.2.1). Alternatively, other pairs of variables may be chosen as the independent variables defining the column performance and each set can vary... 

Lyophilization (Freeze Drying) Lyophilization is most frequently used for heat-labile dosage forms that are unstable in aqueous formulation. The principle of lyophilization can be seen by reference to the phase equilibrium diagram for water (Fig. 15). Water at atmospheric pressure and ambient temperatures is stable in its liquid phase at lOO C the liquid phase attains an equilibrium with its vapor phase. Above 100 C water is stable in its vapor phase. At atmospheric pressures and 0 C the solid (ice) and liquid phases of water are in equilibrium with each other. At vacuum pressures a temperature (the eutectic point) can be reached where the three phases, solid, liquid, and vapor are all in equilibrium with each other. At even lower temperatures and pressures the solid phase comes into equilibrium with the liquid phase. The significance of this is that an aqueous solution can be concentrated by evaporation (sublimation) at low pressures without any necessity for significant heat input. 

In third, we will try to illustrate the dependence of dried coating structure on the dr5dng path by means of the basic phenomena, phase equilibrium. We will also briefly introduce the mechanisms behind the formation of microstructure of various kind of functional films. ... 

Gas-Solid Phase Equilibrium with Adsorption/Desorption and Convective Solid Drying (Adsorption Equilibrium)... 

A comparison of the dry-salt diagrams of the metastable phase equilibrium at 308.15 K and the stable phase equilibrium at 298.15 K for the same system is shown in Figure 8. The metastable crystallization regions of borax and potassium chloride are both enlarged while the crystallized area of other minerals existed is decreased. When compared with the stable system, the solubility of borax in water in the metastable system is increased from 3.13 % to 5.70 %. The metastable phenomenon of borax is obvious in this reciprocal quaternary system. 

No. Composition liquid phase molality, / (mol/kgH20) Janecke index, 7 /(mol/lOOmol dry-salt) Equilibrium solid phases... 

Two-dimensional TLC on polyamide sheets by ascending solvent flow is used to identify all DABTH-amino acids except DABTH-Ile/Leu. No phase equilibrium is necessary, and HrO-acetic acid (2 1) is used for the first dimension and toluene- -hexane-acetic acid (2 1 1, v/v) is used for the second dimension. The sheet is dried after the second run and exposed to HCl vapors when all yellow spots turn red or blue. For discrimination between DABTH-Ile/Leu, one-dimensional separation on polyamide (143) using formic acid-ethanol (10 9, v/v) or one-dimensional separation on silica gel... 

Roy, R. (1956) Aids in hydrothermal experimentation. 2. Methods of making mixtures for both dry and wet phase equilibrium studies. /. Am. Ceram. Soc ... 

Build-up of pressure and salt spalling arise due to solid-phase transformation of anhydrite into decahydrate according to reaction equation (d) because this transformation is connected with a considerable increase of the solid-matter volume. When a porous salt-saturated material is exposed to fluctuating temperatmes 0 and relative humidity RH, such solid-phase transformations in the pore s3fstem of the otherwise dry material will take place under certain conditions. For further explanation of these different hypotheses, we want to estimate by calculation what changes in temperature 0 and relative humidity RH can be expected to generate the solid-phase transformation (d) in a porous salt saturated material. Also we want to make an estimate of the increase in sohd-matter volume by the transformation (d) and an estimate of the influence of the pressure on the phase equilibrium (d). 

No. Composition of liquid phase (mass %) Janecke index/(mol/100 mol dry-salt) Equilibrium... 

The state of equilibrium differs from the equilibrium between water and pure water vapor in that, in a gas phase, there is also inert gas (dry air) present. This means that the water pressure is equal to the total gas pressure, p -- p, + ph, not to the water vapor pressure p, . 

Wet towels hung on a clothesline eventually dry, because the continual motion of molecules in liquid water allows some molecules to escape from the liquid phase (Figure 2-9aV A wet towel left in a closed washing machine, however, stays wet for a long time. This is because water molecules that escape from the surface of the towel remain within the washing chamber (Figure 2-9b). The number of water molecules in the gas phase increases, and the towel recaptures some of these molecules when they collide with its surface. The system soon reaches a condition of dynamic equilibrium in which, for every water molecule that leaves the surface of the towel, one water molecule returns from the gas phase to the towel (Figure 2-9cV Under these conditions, the towel remains wet indefinitely. 

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