Presence of a Solid Phase

Solids affect coalescence in some instances by slowing the rate of film drainage. They can also have the opposite effect of helping to bridge the film, thereby increasing the probability of coalescence. Dispersion is less sensitive to the presence of solids. At low solids concentration there is little effect. At continuous phase concentrations above 10 vol %, a higher average viscosity tends to 

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Environments are either gases or liquids, and inhibition of the former is discussed in Section 17.1. In some situations it would appear that corrosion is due to the presence of a solid phase, e.g. when a metal is in contact with concrete, coal slurries, etc. but in fact the corrosive agent is the liquid phase that is always present. Inhibition of liquid systems is largely concerned with water and aqueous solutions, but this is not always so since inhibitors may be added to other liquids to prevent or reduce their corrosive effects — although even in these situations corrosion is often due to the presence of small quantities of an aggressive aqueous phase, e.g. in lubricating oils and hydraulic fluids (see Section 2.11). 

The solution pH influences a number of factors, and it is not always simple to predict its effect. Thus, thiourea decomposition (in alkaline solution) is generally faster at higher pH. The probability of the presence of a solid phase of Cd(OH)2 and its concentration in the solution are both increased at higher pH (higher OH concentration). The pH is determined, in the example given earlier, by the concentration of ammonia. However, it can be adjusted independent of the ammonia concentration. Addition of an ammonium salt, which with ammonia, acts as a buffer, will lower the pH through the following equilibrium ... 

The various aspects that are to be considered to achieve a proper and efficient catalyst testing approach are presented. This applies to heterogeneous systems in which the catalyst is the solid phase and the reactants are in the gaseous and/or the liquid phase. The presence of a solid phase introduces complicating phenomena on which this chapter focuses. In this respect, homogeneous catalysis is a limiting case and does not need separate treatment. The solid catalyst can be present as either a packed bed of particles, a wash-coated monolith, a fluid bed, an entrained bed, or in a liquid-phase slurry. 

Such a reaction, however, is not generally regarded as an example of slow combustion. Slow combustion is usually facilitated by the presence of a solid phase which may be the combustible substance itself—as in the case of phosphorus—or even an inert substance, such as... 

The data points of Ihle, Neubert, and Wu, for the solubility of deuterium in several Pb-Li compositions are shown in Figure 17. The solid lines at temperatures of 677 and 767°C are interpolations between data points. The gap in the 677 C curve is due to the presence of a solid phase. The data have been extended to the deuterium-in-lithium data from Argonne (28) and the hydrogen-in-lead data from Opie and Grant (29). 

In the model membrane studies discussed here, results from experiments using bovine brain ceramides differed from those using epidermal ceramides in the presence of a solid phase in the former, i.e. a lipid organization in which molecular motion is less than in a gel, and similar to that observed in an anhydrous powder. Model membranes composed of epidermal ceramides are clearly an advantage in studying the behavior of SC intercellular membranes, and appropriate NMR studies to detect such a phase will resolve this issue. One possible explanation is found by considering the kinetics of the formation of the solid phase In the bovine brain ceramide mixtures it was very slow to form, on the order of days to weeks, and was even more sluggish at pH 7.4... 

Heterogeneous nucleation occurs when the presence of a solid phase reduces AGn and thus leads to an increase in Jn. The substrate may be minute particles of a foreign phase or crystals (seeds) of the phase that is crystallizing. 

In the case of a solution in the presence of a solid phase consisting of crystals of an addition compound (cf. chap. XXIII, 2 and 3) it can be easily verified that the system is in an indifferent state if the composition of the solution is the same as that of the crystals. 

Computational fluid dynamics (CFD) is increasingly being utilized to analyze mixing systems, particularly the stirred vessels commonly used for crystallizer operation (Woo et al. 2006). The problem of modeling fluid dynamics in the presence of a solid phase is not trivial, but some workers are starting to make headway in this field. These efforts are referred in Chapter 11. 

In the presence of a solid phase the distribution logarithmic diagrams are called solubility log concentration diagrams. From these diagrams it is possible to find the liquid phase composition (distribution of complexes and free-ion form) of the areas with predominating existence of the particular forms, total and minimum solubility of the solid phase and pH, or precipitant concentration required for separation of the solid phase at a given pH... 

The presence of a solid phase adds considerable complexity to the fluid phase diagram [14, 16]. We discuss here only two cases, one for Type-I fluid phase behavior including a solid phase well below the critical line, and one in which the solid phase reaches into the supercritical regime. F or a full discussion of the latter case, see Peters [16]. 

In a multi-phase catalytic reactor, the reacting species are dissolved in two different fluid phases (e.g., in a gas-liquid system or in liquid-liquid system) which are separated by a phase interface, and the catalyst is located in one of the fluid phases or in a dissolved form (as for example an homogeneous catalyst) or as a third heterogeneous phase (e.g., a solid phase). When a gas-liquid system is in the presence of a solid phase catalyst, the reactor is referred to as a three-phase reactor. Multi-phase reactors represent one of the most important classes of chemical reactors and they are widely used in many industrial sectors, as for example chemical, petrochemical, biotechnological, pharmaceutical and food processing industries (Barnett, 2006 Biardi and Baldi, 1999 Henkel, 2000 Nauman, 2008). Multi-phase reactors have typical industrial application in ... 

The effects of flow rate (flow intensity, turbulence, shear stress) on corrosion have been known for a long time and have been variously called erosion corrosion or flow induced localized corrosion (FILC), which latter term is preferred because it denotes a purely aqueous (liquid) phenomenon, while erosion generally includes the presence of a solid phase. An attempt was made in 1990 to summarize the state of the art of FILC in a symposium [54]. The following is a brief synopsis of the developments in this area, with emphasis on corrosion inhibitor testing. 

As soon as solids appear in the stirred vessel, they have a significant influence on blend time. The correlations known from one-phase operation lose their validity in the presence of a solid phase [14]. In Figure 13.13, the influence of solids concentration is visualized when dealing with solids concentrations larger than Xs = 0.1. Results are presented for both cases, one-phase and two-phase media. As... 

In the case of the mixed kineticsthe diffusion mass transfer in the solid and liquid phases occur with comparable rates) on an ideally flat electrode with = 0 in the presence of a solid phase adsorption effect the diffusion problem (2)-(12) is reduced to the onedimensional task. Its solution is obtained using the method of the integral Laplace-Carson transformation in the form of concentration profiles and voltammogram ... 

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