Solid and liquid phases

The study of the interaction of electromagnetic radiation with solid or liquid matter requires some understanding of these phases. In the discussion of the interaction of radiation with gases it is generally sufficient to consider the energy levels of an individual molecule of a particular gas. Collision-induced phenomena, where at least two gas molecules are involved in a transition, provide an important exception to this rule (Subsection 3.3.d). However, in most cases the interaction of radiation with a gas can be adequately understood by considering quantum processes involving only one molecule. Such is not the case in interactions of radiation with solids or liquids. 

The coupling of the individual oscillators complicates the theoretical treatment of solid matter. Further complexity arises in the treatment of crystal boundaries and of other disturbances of the structure. Lattice periodicity may be intermpted by imperfections or impurities. However, where the crystal periodicity is well-preserved, certain simplifications are permitted in the theoretical treatment. Unfortunately, on real planetary or satellite surfaces matter is rarely found in the form of large crystals. In surface rocks the stmcture usually consists of small, sometimes minute crystals. Very small dust particles of micrometer size are frequently formed by meteoritic impact and by erosion resulting from thermal stresses, wind, or water. 

Good examples of dusty surfaces are found on Mars and the Moon. The theoretical treatment of amorphous substances and liquids is even more difficult. There the periodic lattice stmcture does not exist at all, but the interaction among molecules 

To gain an understanding of the interaction of radiation with solids and liquids we use the complex index of refraction, n, introduced in Section 1.3. The real part 

Equations (1.3.24) to (1.3.26) express the real and imaginary parts of the complex index of refraction in terms of the electric conductivity cr, the dielectric constant e, and the magnetic permeability ju, of the medium. The real part of the index is called the propagation constant and the imaginary part the absorption constant. Neither r nor n, are true constants, but are functions of wavenumber. The electric field of radiation traveling in the jc-direction is [see Eq. (1.3.27)] 

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AC impedance spectroscopy is widely employed for the investigation of both solid- and liquid-phase phenomena. In particular, it has developed into a powerfiil tool m corrosion teclmology and in the study of porous electrodes for batteries [, and ]. Its usage has grown to include applications ranging from... 

The heat capacity can be computed by examining the vibrational motion of the atoms and rotational degrees of freedom. There is a discontinuous change in heat capacity upon melting. Thus, different algorithms are used for solid-and liquid-phase heat capacities. These algorithms assume different amounts of freedom of motion. 

In a filtering centrifuge, separating sohds from liquid does not require a density difference between the two phases. Should a density difference exist between the two phases, sedimentation is usually at a much more rapid rate compared to filtration. In both cases, the solid and liquid phases move toward the bowl under centrifugal force. The sohds are retained by the filter medium, while the liqmd flows through the cake solids and the filter. This is illustrated in Fig. 18-138/ . 

Influence of the various factors in static conditions (concentration of heavy metals, both time of contact and ratio of solid and liquid phase, pH of medium) on solution of Pb(II), Cu(II), Cd(II) and Zn(II) from water solutions is studied and the optimal conditions of their extraction by organosilica sorbents modified by ions of Al(III) and Cu(II) are found. 

The easiest way to understand the SMB concept is to consider a true moving bed (TMB) as described in Eigure 10.1, in which a countercurrent contact is promoted between the solid and liquid phases. The solid phase moves down the column due to gravity and exits the system in Zone I. The liquid (eluent) stream follows exactly the opposite direction. It is recycled from Zone IV to Zone I. The feed, containing components A and B are injected at the middle of the column, and the fresh eluent is replenished in Zone I. 

The vapor pressure (P ) of a pure liquid at a given temperature (T) is the pressure exerted by its vapor in equilibrium with the liquid phase in a closed system. All liquids and solids exhibit unique vapor pressure-temperature curves. For instance, in Figure 2-79, lines BA and AC represent the equilibrium vapor pressure curves of the solid and liquid phases, respectively. 

Corrosion by liquid metals is usually controlled by diffusion processes in the solid and liquid phases and, unlike aqueous corrosion, does not generally involve galvanic effects, and, even where electrochemical phenomena are known to occur, it has not, in general, been demonstrated that they have been responsible for a significant portion of the corrosion observed . In... 

For a pure substance, the melting point is identical to the freezing point It represents the temperature at which solid and liquid phases are in equilibrium. Melting points are usually measured in an open container, that is, at atmospheric pressure. For most substances, the melting point at 1 atm (the normal melting point) is virtually identical with the triple-point temperature. For water, the difference is only 0.01°C. 

Freezing point The temperature at which the solid and liquid phases of a substance are at equilibrium, 269 electrolytes, 275 lowering, 277t... 

It is clear that the cell voltage is nearly independent of the pressure if the reaction takes place between solid and liquid phases, where the change in volume is negligibly low. On the other hand, in reactions involving the evaluation or disappearance of gases this volume has to be considered [11],... 

Fine suspensions are reasonably homogeneous and segregation of solid and liquid phases does not occur to any significant extent during flow. The settling velocities of the particles are low in comparison with the liquid velocity and the turbulent eddies within the fluid are responsible for the suspension of the particles. In practice, turbulent flow will always be used, except when the liquid has a very high viscosity or exhibits non-Newtonian characteristics. The particles may be individually dispersed in the liquid or they may be present as floes. 

FIGURE 8-7 The phase diagram for carbon dioxide (not to scale). The liquid can exist only at pressures above 5.1 atm. Note the slope of the boundary between the solid and liquid phases it shows that the freezing point rises as pressure is applied. 

There is a large variety of atmospheric sulfur compounds, in the gas, solid, and liquid phases. Table 7-3 lists a number of gaseous compounds, range of concentration, source, and sink (where known). As this list illustrates, a significant number of these gases contribute to the existence of oxidized sulfur in the forms of SO2 and sulfate aerosol particles. Table 7-4 lists the oxy-acids of sulfur and their ionized forms that could exist in the atmosphere. Of these the sulfates certainly are dominant, with H2SO4 and its products of neutralization with NH3 as the most frequently reported forms. 

Hydrogen bonds can exist in the solid and liquid phases and in solution. Many organic reactions that will be discussed in later chapters can be done in aqueous... 

The need to separate solid and liquid phases is probably the most common phase separation requirement in the process industries, and a variety of techniques is used (Figure 10.9). Separation is effected by either the difference in density between the liquid and solids, using either gravity or centrifugal force, or, for filtration, depends on the particle size and shape. The most suitable technique to use will depend on the solids concentration and feed rate, as well as the size and nature of the solid particles. The range of application of various techniques and equipment, as a function of slurry concentration and particle size, is shown in Figure 10.10. 

The conditions for a complete separation of a binary mixture can be defined in terms of the Yj model parameters, which are directly related with the TMB (SMB) operating variables (fluid and solid velocities in the four sections of the TMB unit). From the constraints presented, those related to sections II and III play the crucial role on the separation performance of the TMB. It is in these central zones that the separation between the two species takes place. The role of the adjacent sections (I and IV) is to prevent cross-contamination and to allow the improvement of the continuous operation of the system by regenerating the solid and liquid phases. Taking into account these considerations, a region of complete separation in a Ym-Yn plane can be defined. Considering that the constraints concerning sections I and IV are fulfilled, the YnrYn plot is 311 important tool in the choice of best operating conditions. 

Thus, in according to the concept of equilibrium distribution, the relation of an organic pollutant concentration in the soil solid and liquid phase is constant at any moment (Vasilyeva and Shatalov, 2004). The example of such an approach application for assessing exposure pathways of POPs to living biota is shown in Box 1. 

All components in the soil solution are to a greater or lesser extent distributed unevenly between the solid and liquid phases. Anions are generally only... 

Two types of distribution coefficients are commonly measured and used in describing the distribution between solid and liquid phases. The first and simplest is the distribution between total solid and liquid phases. This can be represented by Kd, as given in the equation in Figure 5.11. Here, kg is kilogram and L is liter of soil solution. 

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