Separation Phenomena

The separation operation/equipment and mixing operation/equipment are related to each other as the front and rear of an event. 

In Chapter 2, the evaluation indices of mixing operations/equipment are discussed. Therefore, as a logical continuation from the preceding chapter, it is natural to discuss the evaluation of separation operations/equipment in this chapter. 

In general, in industrial processes, the necessity of a separation operation occurs after the mixing/reaction operations. Therefore, the separation operation is an indispensable process for chemical engineering. The purpose of the separation process is different from that of the mixing process, and the purpose of separation is only to separate substances depending on the requirements. However, identical to the mixing phenomenon, the separation phenomenon is definitely a function of space and time. The separation equipment is classified into two groups  

Let us deal with separation operations in chemical engineering. The representative separation operations are extraction, absorption, and crystallization. 

The aim of extraction is to promote mass transfer or extraction reaction between two phases (a mutually insoluble liquid-liquid system) by dispersing one liquid phase in another. In principle, creating a larger interface area in this operation is advantageous. However, it is necessary to consider that interface phenomena depend on the type of system. Extractors are classified into three types  

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While the stick plot examples already presented show net and multiplet effects as separate phenomena, the two can be observed in the same spectrum or even in the same NMR signal. The following examples from the literature will illustrate real life uses of CIDNP and demonstrate the variety of structural, mechanistic, and spin physics questions which CIDNP can answer. 

J. M. Lerat, in P. Louvet, P. Noe, and Soubbaramayer, eds.. Proceedings of the Second Workshop on Separation Phenomena in Eiquids and Gases, Versailles,... 

Absorption, distribution, biotransformation, and excretion of chemical compounds have been discussed as separate phenomena. In reality all these processes occur simultaneously, and are integrated processes, i.e., they all affect each other. In order to understand the movements of chemicals in the body, and for the delineation of the duration of action of a chemical m the organism, it is important to be able to quantify these toxicokinetic phases. For this purpose various models are used, of which the most widely utilized are the one-compartment, two-compartment, and various physiologically based pharmacokinetic models. These models resemble models used in ventilation engineering to characterize air exchange. 

Recently [63], we studied the behavior of two-enzyme system catalyzing two consecutive reactions in a macroheterogeneous medium (modified Lewis cell). The system consisted of lipase-catalyzed hydrolysis of trilinolein and subsequent lipoxygenation of liberated fatty acids (Fig. 3). Our approach compared the kinetic behavior of coupled enzymes in the Lewis cell with the sequential study of separated phenomena presented before ... 

This type of analysis is useful for studying the phase separation phenomena, also in detecting influences of external fields [218] (strain, etc.). In particular, by investigating speckles on scattering patterns, a certain information about interface fluctuations can be obtained [214]. 

Phase separation (precipitation) of a polymer strongly depends on all its molecular characteristics. On the one hand, this allows very efficient separations in polymer HPLC utilizing phase separation and re-dissolution processes [20]. On the other hand, due to complexity of phase separation phenomena, the resulting retention volumes of complex polymers may simultaneously depend on several molecular characteristics of separated macromolecules. This may complicate interpretation of the separation results. Both precipitation and redissolution of most polymers is a slow process. It may be affected by the presence of otherwise inactive surface of the column packing. Therefore, the applicability and quantitative control of the phase separation phenomena may be limited to some specific systems of polymer HPLC. 

Despite the reduction in activity that occurs as a drug leaves its site of action, it may remain in the body for a considerable period, especially if it is strongly bound to tissue components. Thus, reduction in pharmacological activity and drug elimination are to be seen as related but separate phenomena. 

Given that the source of oxidants for S02 in both the gas and liquid phases is the VOC-NO chemistiy discussed earlier and that a major contributor to acid deposition is nitric acid, it is clear that one cannot treat acid deposition and photochemical oxidant formation as separate phenomena. Rather, they are very closely intertwined and should be considered as a whole in developing cost-effective control strategies for both. For a representative description of this interaction, see the modeling study of Gao et al. (1996). 

In a crystalline antiferromagnet the moment on each ion is less than it would be on the free ion. There are two separate phenomena involved here. One is the zero-point energy of the spin waves, which reduces the moment on each ion by a factor (Anderson 1952, Ziman 1952)... 

Point of inversion. The action of a point of inversion is described above in the context of improper rotation axes. Note that planes of symmetry and points of inversion are somewhat redundant symmetry elements, since they are already implicit in improper rotation axes. However, they are somewhat more intuitive as separate phenomena than are S axes, and thus most texts treat them separately. 

The primary objective of the present discussion is to show the intrinsic connection between surface tension and the van der Waals energy of attraction between macroscopic bodies. The connection not only provides computational options but also —and more importantly — unites two apparently separate phenomena and strengthens our confidence in the correctness of our understanding. 

The arguments in favour of treating complex formation/anation processes as mechanistically separate phenomena have therefore lost some of their force as the subject has developed in recent years and, for this reason, only certain aspects will be discussed in this section. 

When two different polymer solutions are mixed, they frequently undergo one or several distinct types of interaction, which in each case can lead to phase separation at polymer concentrations above a certain critical level [12]. In one case, two solution phases of approximately equal volume are formed, consisting of polymer A- and polymer B-rich solutions, respectively. This phase separation is called incompatibility, or simple coacervation. In the second case, two phases are formed but both polymers are concentrated in one of the phases (the precipitate ) while the other phase (the supernatant ) may be essentially polymer free. This separation is called complex coacervation. The two phase separation phenomena are shown in Fig. 2. 

Particularly strong and complex interactions prevail among reaction and separation systems that are generally not at all or not fully exploited as a result of the application of the available synthesis methods for reactor networks and separation systems in isolation. The lack of generality in the synthesis methods is a tribute to the nonlinear process models required to capture the reaction and separation phenomena as well as to the vast number of feasible process design candidates. These complexities even make it difficult to synthesize the decomposed subsystems, which are typically reactor networks, separation systems, reactor-separator-recycle systems, and reactive separation systems. The development of reliable synthesis tools for these sub-systems is still an active research area. 

An aerosol is generally defined as a suspension of solid or liquid particles in a gas, and the most evident example of an aerosol is the air (Horvath, 2000). However, in atmospheric research, the term aerosol usually denotes the suspended particles that contain a large proportion of condensed matter, whereas clouds are considered as separate phenomena (Poschl, 2005). 

Is there no rigorous way to separate static and dynamic electron correlation Dynamic correlation is present in any system with two or more electrons, but static correlation requires degenerate or near-degenerate partially-filled orbitals, a feature absent in normal closed-shell molecules. So in this sense they are separate phenomena. In another sense they are intertwined methods that go beyond the Hartree-Fock in invoking more than one determinant, namely Cl and its coupled cluster variant, improve the handling of both phenomena. 

ORBITAL ORDERING AND PHASE SEPARATION PHENOMENA IN LIGHTLY DOPED MANGANITES... 

Orbital ordering andphase separation phenomena in lightly doped manganites... 

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