Reacting systems, phase separation

Research on the development of separation methods for the multiphase reacting system led to the development of a three phase (oil, water, and a solid) separation process. A patent was awarded in 1998 in US [53] and subsequently in some other countries... 

Heterogeneous solid state reactions occur when two phases, A and B, contact and react to form a different product phase C. A and B may be either chemical elements or compounds. We have already introduced this type of solid state reaction in Section 1.3.4. The rate law is parabolic if the reacting system is in local equilibrium and the growth geometry is linear. The characteristic feature of this type of reaction is the fact that the product C separates the reactants A and B and that growth of the product proceeds by transport of A and/or B through the product layer. 

In this case of three-monomer polyurethane synthesis, there is no thermodynamic driving force for phase separation. The formation of clusters is fully controlled by the initial composition of the system, the reactivity of functional groups, and the network formation history (one or two stages, macrodiol or triol reacted with diisocyanate first, etc.). 

Nanostructures primarily result from polyelectrolyte or interpolyelectrolyte complexes (PEC). The PEC (also referred to as symplex [23]) is formed by the electrostatic interaction of oppositely charged polyelectrolytes (PE) in solution. The formation of PEC is governed by physical and chemical characteristics of the precursors, the environment where they react, and the technique used to introduce the reactants. Thus, the strength and location of ionic sites, polymer chain rigidity and precursor geometries, pH, temperature, solvent type, ionic strength, mixing intensity and other controllable factors will affect the PEC product. Three different types of PEC have been prepared in water [40] (1) soluble PEC (2) colloidal PEC systems, and (3) two-phase systems of supernatant liquid and phase-separated PEC. These three systems are respectively characterized as ... 

Water-rock interaction and phase separation are processes that are inextricably finked. As water passes through the hydrothermal system it wiU react with the rock and/or sediment substrate that is present (Figure 5). These reactions begin in the downflow zone, and continue throughout. When... 

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