Separation processes selection

In summation, the adsorptive bubble separation process, in theory, can remove or separate almost any kind of light-weight and/or surface-active substances from water. Because there are various types of adsorptive bubble separation processes, selection of an appropriate type for a specific application is an important skill (43,84). 

The wide variety of possible choices of separation processes bas been catalogued by King. Also, a detailed discussion of procedures for selecting a separation process is provided by Null in Chepter 22. Hare, some comments on separation process selection are included to provide some perspective for later discussion. 

Figure 4. Solids/liquid separation process selection diagram. Mass concentration isopleths computed assuming spherical particles, specific gravity of 1020 kg m. (Criteria for region boundaries discussed in text.)...

When using ranked lists as a basis for separation process selection, avoid separation factors close to one and draw on experience to weigh theoretical potential with practical expectations. A more detailed discussion of the selection of a separation process is given in Chr r 22. 

Until recently, there were only few ways to introduce specific modifications into the reaction center structure which were suited for a parametric study of charge separation processes. Selective modifications were limited to the two quinones, and Qg (Warncke Dutton), the presence and nature of the divalent metal ion located between and Qg [3], and the removal of the H-protein subunit [4]. The only possibility to interfere with one of the four bacteriochlorophylls, the one at the site Bg in reaction centers of Rhodobacler (Rb.) sphaeroides, consisted in the borohydride treatment [5] and the chemistry of this procedure is still under debate 16]. 

Many topics could not be covered in this book. A much abbreviated list includes the molecular basis of equilibrium partitioning of molecules between different phases enthal-pic and entropic contributions to partitioning/selectivity the molecular basis of afBnity binding in bioseparations nonisothermal analysis of absorption columns, adsorption beds, distillation columns, etc. multicomponent multistage separations in distillation columns numerical methods for multicomponent multistage countercurrent separation processes experimental methods in separation studies hybrid separation processes selection of separation processes for solving a separation problem reaction-separation/ separation-reaction/reaction-separation-reaction processes and devices. 

Flotation reagents are used in the froth flotation process to (/) enhance hydrophobicity, (2) control selectivity, (J) enhance recovery and grade, and (4) affect the velocity (kinetics) of the separation process. These chemicals are classified based on utili2ation collector, frother, auxiUary reagent, or based on reagent chemistry polar, nonpolar, and anionic, cationic, nonionic, and amphoteric. The active groups of the reagent molecules are typically carboxylates, xanthates, sulfates or sulfonates, and ammonium salts. 

Whereas Hquid separation method selection is clearly biased toward simple distillation, no such dominant method exists for gas separation. Several methods can often compete favorably. Moreover, the appropriateness of a given method depends to a large extent on specific process requirements, such as the quantity and extent of the desired separation. The situation contrasts markedly with Hquid mixtures in which the appHcabiHty of the predominant distiHation-based separation methods is relatively insensitive to scale or purity requirements. The lack of convenient problem representation techniques is another complication. Many of the gas—vapor separation methods ate kinetically controUed and do not lend themselves to graphical-phase equiHbrium representations. In addition, many of these methods require the use of some type of mass separation agent and performance varies widely depending on the particular MSA chosen. 

In the physical separation process, a molecular sieve adsorbent is used as in the Union Carbide Olefins Siv process (88—90). Linear butenes are selectively adsorbed, and the isobutylene effluent is distilled to obtain a polymer-grade product. The adsorbent is a synthetic 2eohte, Type 5A in the calcium cation exchanged form (91). UOP also offers an adsorption process, the Sorbutene process (92). The UOP process utilizes ahquid B—B stream, and uses a proprietary rotary valve containing multiple ports, which direct the flow of Hquid to various sections of the adsorber (93,94). The cis- and trans-isomers are alkylated and used in the gasoline blending pool. 

The selection of a separation process depends on many factors, not the least of which is the type of gas to be purified. Table 7 gives some... 

Deviations from Raonlt s law in solution behavior have been attributed to many charac teristics such as molecular size and shape, but the strongest deviations appear to be due to hydrogen bonding and electron donor-acceptor interac tions. Robbins [Chem. Eng. Prog., 76(10), 58 (1980)] presented a table of these interactions. Table 15-4, that provides a qualitative guide to solvent selection for hqnid-hqnid extraction, extractive distillation, azeotropic distillation, or even solvent crystallization. The ac tivity coefficient in the liquid phase is common to all these separation processes. 

Process Selection The preceding sec tions present many process cycles and their variations. It is important to have some gmdelines for design engineers to narrow their choice of cycles to the most economical for a particular separation. Keller and coworkers [Keller et al., gen. refs.] have presented a method for choosing appropriate adsorp-... 

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