Vapor pressure effect

Becaus-e of the similarity in the relations for osmotic pressure in dilute solutions and the equation for an ideal gas, van t Hoff proposed his bombardment theory in which osmotic pressure is considered in terms of collisions of solute molecules oil the semipeniieable membrane. This theoiy has a number of objections and has now been discarded. Other theories have also been put forward involving solvent bombardment on the semipermeable membrane, and vapor pressure effects. For example, osmotic pressure has been considered as the negative pressure which must be applied to the solvent to reduce its vapor pressure to that of the solution. It is, however, more profitable to interpret osmotic pressures using thermodynamic relations, such as the entropy of dilution,... 

DNT, observed in TNT and cast explosives in addition to most smokeless powders, was tested at levels from 10.0 mg to 1.25 g. Response to the odor chemical varied across all concentrations however, better results were generally observed at higher concentrations. The canines tested were observed to favor the DNT to the parent explosive TNT, although whether this was a result of the chosen odorant during training or a vapor pressure effect remains unclear. Interestingly, 100 xg of analytical-grade TNT received fewer positive... 

Vacuum pump modifications usually involve conversion of a once-through liquid ring pump to a full sealant recovery pump. This will eliminate any continuous liquid dischargement to the drain. The sealant can either be water or oil. The use of water places limitations on the maximum vacuum depth, which is reasonably attenuated because of the vapor pressure effects. The use of oil eliminates this maximum vacuum depth limitation. 

Above the crossover pressure, the opposite eifect occurs. This behavior can be understood by considering two opposing effects of temperature on solubility (Chimowitz 2005). The vapor pressure of the solid solute always increases with temperature, while the density (or solvent power) of supercritical carbon dioxide decreases. Below the crossover pressure where the compressibility is larger, the density effect dominates, and the solubility decreases with increasing temperature. At pressures above the crossover pressure, the vapor-pressure effect dominates hence solubility increases with temperature. 

Table III. Phase and Temperature (Vapor Pressure) Effects on C8 Products from tert-C H. Reaction with Isobutylene...

For the sake of comparison, the parameters concerning the models developed by Dunn and Tichenor (1988) and De Bortoli et al. (1996) are summarized in Table 2.3-1. The dilution model represents the simplest situation and results if the sink effects and the vapor pressure effect (kg) are neglected. 

The region of pressure below the crossover pressure is known as the retrograde region. In this range of pressure, solubility decreases with an increase in temperature because the density of the SCF falls sharply. The decrease in density is sufficient to overcome any increases in solute vapor pressure that would normally lead to an increase in solubility. Above the crossover pressure, the decrease in solvent density is less sensitive to temperature and so solubility increases with temperature because the vapor pressure effect becomes dominant. 

To study the down stream vapor pressure effects that exist when permeating into non-zero water vapor pressure, nitrogen sweep gas of desired water vapor pressure was used on the permeate side. The humidity of the sweep and feed gas exiting the membrane device was measured to estimate the water permeability. 

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