Dense-media separation additives

Creaming is the separation of dispersed droplets from the continuous phase under the action of gravity. The droplets do not coalesce when they touch. If the dispersed medium is less dense than the continuous phase, the emulsion will cream upwards. Conversely, for a more dense dispersed phase, the emulsion will cream downwards or sediment. Creaming will inevitably occur in any dilute emulsion in accordance with Stokes s law if the phases are not exactly equal in density. Creaming is, therefore, a trivial form of instability that can be avoided by addition of thickeners that confer plastic rheology, and, therefore, yield value to the aqueous phase. 

The chief advantages to using dense CO2 as the reaction medium were claimed to be its inertness, its general ability to dissolve the reactants, and its easy separation from the reaction mixture. No mechanistic work was reported, but the same mechanism as previously proposed in alkane solvents was suggested, that is, the key step was oxidative addition to the excited state of the metal complex. The C02/Rh complex system was also reported to be an effective photocatalytic system for the dehydrogenation of cyclooctane. 

Another important topic is the solution of nonlinear algebraic systems, which demands very robust algorithms. Chapter 7 illustrates the numerical methods for square systems in their sequential and parallel implementation. In addition to this, methods and techniques are proposed by separating the small and medium dimension problems, which are considered dense for large-scale systems, where the management of matrix sparsity is crucial. Many practical examples are provided. 

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