Heterogeneous two-phase system

A disperse system is defined as a heterogenous, two-phase system in which the internal (dispersed, discontinuous) phase is distributed or dispersed within the continuous (external) phase or vehicle. Various pharmaceutical systems are included in this definition, the internal and external phases being gases, liquids, or solids. Disperse systems are also important in other fields of application, e.g., processing and manufacturing of household and industrial products such as cosmetics, foods, and paints. 

The Gibbsian equilibration principles as developed previously (Chapter 5) apply straightforwardly to heterogeneous as well as homogeneous systems. Consider, for example, the heterogeneous two-phase system of phases a, /3. Extensive properties such... 

Equation (11.163) shows how the isochoric heat capacity of a heterogeneous two-phase system can be evaluated from known isobaric properties (CP, aP) of the individual phases and the direction y(T of the coexistence coordinate cr. 

Matsuo, Nozaki, and Jyo (20) showed that heterogeneity at 100 A scale and under can be detected readily. Thus, microscopy can offer a measure of heterogeneity down to 0.01 p scale which is much smaller than the domain size of most polyblends. Results of microscopy have established convincingly that nearly all polyblends are heterogeneous two-phase systems. How does one describe the results Obviously, heterogeneity as revealed by microscopy is a relative property. If compatibility is used in a qualitative sense, a polyblend with a finer domain size will be more compatible than one with a larger size, provided equilibrium size distribution has been attained in both cases. 

Bubbling Fluidized Bed Catalytic Reactors (Heterogeneous Two-Phase System)... 

Digital simulation based on an appropriate mathematical model is the best tool in order to understand the dynamic behaviour of the column We used a set of equations which models every stage as an heterogeneous two-phase system consisting of the two totally mixed homogeneous phases vapour and liquid (Figure 2). 

Figure 2. Heterogeneous two-phase system (a) and assumed mole fractions near...

For the production of chemicals, the rate of the reaction is a key parameter for the productivity defined in Equation (5) as the number of molecules produced per time. In homogeneous systems, the reaction rate depends on temperature, pressure, and composition [1]. In the case of solarthermal cycles, a metal oxide is used for the C02-splitting reaction rendering the reaction medium a heterogeneous two-phase system consisting of a solid (metal, metal oxide) and a fluid (CO2, CO, or carrier gas with O2). Therefore, the reaction kinetics becomes much more complex. Whereas microscopic kinetics only deals with time-dependent progress of the reaction, macroscopic kinetics additionally takes the heat- and mass-transport phenomena in heterogeneous systems into account. The transfer of species from one phase to the other must be considered in the overall mass balance [1]. The reaction of a gas with a porous solid consists of seven steps ... 

Solutions. A solution is defined as a homogeneous mixture of two or more substances, which has tlie same chemical composition and the same physical properties throughout. All gas mixtures are examples of solutions since gases are completely miscible with one another. Similarly, liquid mixtiues of alcohol and water are solutions since they too are homogeneous, single-phase systems. On the other hand, a liquid hydrocarbon and water do not form solutions since these two liquids do not dissolve in one another and a heterogeneous, two-phase system results. In general, the more closely two substances resemble one another chemically, the more likely are they to form a solution. 

Alternatively, if introduction of water in the system is not considered a problem (e.g. if water is used as a solvent or cosolvent in a homogenous or heterogeneous, two-phase, system), the enzyme can be added as an aqueous formulation. Advantages are also reported on the use of reversed micelles (detergent micelles containing aqueous enzyme in organic media). In any case, for all reaction conditions, the use of an immobilized enzyme preparation should be considered as outlined below. 

Reactions are carried out in a heterogeneous two-phase system in which one phase provides anions or a base for their generation, whereas the second phase contains organic reactants and PTC catalyst. Ionic reagents may be dissolved in the aqueous phase (liquid-liquid, LL-PTC) or used in the form of powdered solids (solid-liquid, SL-PTC) suspended in the organic medium. 

Polymers differ from other solids because they may absorb large amounts of solvents without dissolving. They also undergo large deformations when relatively small forces are involved. Swelling oeeurs in a heterogeneous two phase system a solvent surrounding a swollen body also called gel. Both phases are separated by the phase boundary permeable to... 

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