Liquid solutions surroundings

Cg = the concentration of the saturated solution in contact with the particles, D = a diffusion coefficient (approximated by the Hquid-phase diffusivity), M = the mass of solute transferred in time t, and S = the effective thickness of the liquid film surrounding the particles. For a batch process where the total volume H of solution is assumed to remain constant, dM = V dc and... 

The cage effect described above is also referred to as the Franck-Rabinowitch effect (5). It has one other major influence on reaction rates that is particularly noteworthy. In many photochemical reactions there is often an initiatioh step in which the absorption of a photon leads to homolytic cleavage of a reactant molecule with concomitant production of two free radicals. In gas phase systems these radicals are readily able to diffuse away from one another. In liquid solutions, however, the pair of radicals formed initially are caged in by surrounding solvent molecules and often will recombine before they can diffuse away from one another. This phenomenon is referred to as primary recombination, as opposed to secondary recombination, which occurs when free radicals combine after having previously been separated from one another. The net effect of primary recombination processes is to reduce the photochemical yield of radicals formed in the initiation step for the reaction. 

Miniaturized and robust optical fiber sensors capable of accurate and reliable measurement of refractive index of the surrounding environment have attracted tremendous interest in recent years. One of the driving forces for the development of these fiber optic devices is their broad applications in chemical sensing. When placed in the liquid solution or gas mixture, these fiber sensors can detect the chemical composition change by monitoring its refractive index variation. These... 

Diffusion of the exchanged ions through the liquid film surrounding the resin bead into the bulk solution. 

Solution atomization involves dissolution of a relatively nonvolatile liquid (solute) in a volatile solvent and atomization of the solution. During the atomization, the solvent material will evaporate in surrounding medium (air), leaving only nucleus droplets of the nonvolatile solute. The final droplet size is a function of the initial droplet size, the mass concentration of the solute, and the density ratio of the solution to the solute. The limitation of this technique lies in that it requires the dissolution of the liquid to be dispersed in a solvent. 

It can be seen that the most probable lifetime becomes shorter and the width of the distribution broader as the temperature is increased. For similar temperatures in liquid solution, the lifetime is unmeasurably short ( x< 0.1 nsec). Therefore, and the width of the distribution reflect the effect of the surrounding in slowing down k and not a classical activation barrier effect. 

The word electrokinetic implies the joint effects of motion and electrical phenomena. We are interested in the electrokinetic phenomena that originate the motion of a liqnid within a capillary tube and the migration of charged species within the liquid that surrounds them. In the first case, the electrokinetic phenomenon is called electroosmosis whereas the motion of charged species within the solution where they are dissolved is called electrophoresis. This section provides a brief illns-tration of the basic principles of these electrokinetic phenomena, based on text books on physical chemistry [7-9] and specialized articles and books [10-12] to which a reader interested to stndy in deep the mentioned theoretical aspects should refer to. 

Generally, the expression f/fTe = y, xt = a, is referred to as the activity of the compound. That is, a, is a measure of how active a compound is in a given state (e.g., in aqueous solution) compared to its standard state (e.g., the pure organic liquid at the same T and p). Since yt relates a, , the apparent concentration of i, to the real concentration xt, it is only logical that one refers to yt as the activity coefficient. It must be emphasized here that the activity of a given compound in a given phase is a relative measure and is, therefore keyed to the reference state. The numerical value of Yi will therefore depend on the choice of reference state, since, as we have seen in Section 3.2, molecules of i in different reference states (i.e., liquid solutions) interact differently with their surroundings. 

In the regions surrounded by the liquidus and solidus cfe and deg), a solid phase coexists with a liquid phase. Consider the region cfe. Within this region, pure solid A can coexist with a number of different liquid solutions. Since solid A is the only solid present in this region, it is called the primary field of A. Similarly the region of deg is the primary field of B. 

A dispersion of liquid-in-gas-in-liquid in which a droplet of liquid is surrounded by a thin layer of gas that in turn is surrounded by bulk liquid. Example In an air-aqueous surfactant solution system this dispersion would be designated as water-in-air-in-water, or W/A/W, in fluid film terminology. A liquid-liquid analogy can be drawn with the structures of multiple emulsions. See also Fluid Film. 

The adsorption and elution operations that the biosolute(s) undergo as they proceed along the column bed can thus be considered as a series of diffusion, convection, and reaction steps. In the adsorption process, the solute(s) in the feed must diffuse through a liquid film surrounding... 

Rate of Gas Transfer. In order to remove ammonia from water, the dissolved NH3 molecules must first move from the bulk liquid solution to the air-water interface, and then from the interface to the stripping air flow. Therefore, there are two factors that affect the rate of ammonia gas transfer from the liquid to the surrounding atmosphere. 

Many solids do dissolve in liquids by endothermic processes, however. The reason such processes can occur is that the endothermicity can be outweighed by a large increase in disorder of the solute during the dissolution process. The solute particles are highly ordered in a solid crystal, but are free to move about randomly in liquid solutions. Likewise, the degree of disorder in the solvent increases as the solution is formed, because solvent molecules are then in a more random environment. They are surrounded by a mixture of solvent and solute particles. 

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