Liquid-solid systems systems

Examples of solid - liquid systems with two liquid layers are given below the temperature is the temperature at which the two layers separate or the quadruple point. 

For solid-liquid systems, settling velocities of the 10, 50. and 90 percent by w eight fractions of particle size distribution must be available from calculations or measurements. 

While the surface tension of the adhesive, is easily measured in the laboratory, the other terms in Wa, by themselves, are not. A second easily measurable property associated with the solid-liquid-air system, however, is the contact angle, 9, the angle, drawn in the liquid, between the solid-liquid and the liquid-air interfaces, drawn in the plane perpendicular to the three-phase interline, as shown in Fig. 4. Minimization of the free energy of the solid-liquid-air... 

Crystallization Process Systems brings together essential aspects of the concepts, information and techniques for the design, operation and scale up of particulate crystallization processes as integrated crystal formation and solid-liquid separation systems. The focus of the book, however, is on crystallization only dealing with related unit operations as far as is necessary. It is therefore... 

Considering a solid-liquid system, this relationship may be combined with the well-known Young s equation to eliminate the interfacial free energy. Hence,... 

For the solid-liquid system changes of the state of interface on formation of surfactant adsorption layers are of special importance with respect to application aspects. When a liquid is in contact with a solid and surfactant is added, the solid-liquid interface tension will be reduced by the formation of a new solid-liquid interface created by adsorption of surfactant. This influences the wetting as demonstrated by the change of the contact angle between the liquid and the solid surface. The equilibrium at the three-phase contact solid-liquid-air or oil is described by the Young equation ... 

Brown, N. P. and Heywood, N. I. (eds) Slurry Handling. Design of Solid-Liquid Systems (Elsevier. Amsterdam, 1991). 

Phase transfer catalysis (PTC) refers to the transfer of ions or organic molecules between two liquid phases (usually water/organic) or a liquid and a solid phase using a catalyst as a transport shuttle. The most common system encountered is water/organic, hence the catalyst must have an appropriate hydrophilic/lipophilic balance to enable it to have compatibility with both phases. The most useful catalysts for these systems are quaternary ammonium salts. Commonly used catalysts for solid-liquid systems are crown ethers and poly glycol ethers. Starks (Figure 4.5) developed the mode of action of PTC in the 1970s. In its most simple... 

Lee, Y.N. and Wiley, R.C., Betalaine yield from a continuous solid-liquid extraction system as influenced by raw product, post-harvest and processing variables, J. Food ScL, 46, 421, 1981. 

In earlier work, Bhaumik and Kumar (1995) have reported that the use of two liquid phases in the oxidation of hydrophobic organic substances with aqueous H2O2 using titanium silicate as the catalyst not only enhances the rate of oxidation but also improves selectivity for species like toluene, anisole, and benzyl alcohol. For a single liquid phase acetonitrile was u.sed a solvent. The solid-liquid system gives high ortho selectivity. Thus, in the case of anisole the ratios of o to p for. solid-liquid and solid-liquid-liquid system were 2.22 1 and 0.35 1, respectively. 

FIG. 20-36 Regimes of separation in a liquid-solid-liquid system. Phase 1 = particle phase 2 = liquid (dispersed) phase 3 = liquid (continuous). 

The ability to determine in advance which of the separation regimes is most advantageous for a given liquid-solid-liquid system would be desirable. No set of criteria with which to make this determination presently exists. Work has been done with respect to the... 

When using a solid-liquid system do not charge all the components in the reactor at once. 

The starting reagents in Gabriel amine synthesis, N-alkylphthalimides, were obtained under the action of microwave irradiation in a solid-liquid PTC system. The reactions were conducted with high yield (50-90%) simply by mixing phthalimide... 

Caution must be exercised in the addition of the glacial acetic acid in order to avoid frothing of the hot solution. The frothing becomes most vigorous as the 6-aminouracil begins to precipitate from the solution. The heating and subsequent neutralization assure cycli-zation of the initially formed cyanoacetylurea to 6-aminouracil. The nitrosation is carried out on the two-phase (solid-liquid) system. 

Scale-up equations for liquid, gas-liquid, and solid-liquid systems are detailed in [167,199,201,206]. 

Due to the great similarity of the chemical properties of the rare earth elements, their separation represented, especially in the past, one of the most difficult problems in metallic chemistry. Two principal types of process are available for the extraction of rare earth elements (i) solid-liquid systems using fractional precipitation, crystallization or ion exchange (ii) liquid-liquid systems using solvent extraction. The rare earth metals are produced by metallothermic reduction (high purity metals are obtained) and by molten electrolysis. 

Solid-liquid phase systems with no added solvent produce esters in high yield [e.g. 2, 3] and are particularly Useful when using less reactive alkyl halides [e.g. 15], for the preparation of sterically hindered esters [16], or where other basic sites within the molecule are susceptible to alkylation, e.g. anthranilic acid is converted into the esters with minimal A-alkylation and pyridine carboxylic acids do no undergo quat-emization [17]. Excellent yields of the esters in very short reaction times (2-7 minutes) are also obtained when the two-phase system is subjected to microwave irradiation [18]. Direct reaction of the carboxylic acids with 1,2-dichloroethane under reflux yields the chloroethyl ester [19], although generally higher yields of the esters are obtained under microwave conditions [20]. 

Method B (solid liquid systems) The ester (10 mmol) is shaken with powdered KOH (2.8 g, 50 mmol) and Aliquat (0.48 g, l mmol) for 5 min at room temperature and then left at 85°C until TLC analysis shows the hydrolysis to be complete. The mixture is acidified with aqueous HCl and the acid (>90%) is collected (if solid) or extracted with Et20 or CH2Cl2 (if a liquid). 

Solid lithium aluminium hydride can be solublized in non-polar organic solvents with benzyltriethylammonium chloride. Initially, the catalytic effect of the lithium cation in the reduction of carbonyl compounds was emphasized [l-3], but this has since been refuted. A more recent evaluation of the use of quaternary ammonium aluminium hydrides shows that the purity of the lithium aluminium hydride and the dryness of the solvent are critical, but it has also been noted that trace amounts of water in the solid liquid system are beneficial to the reaction [4]. The quaternary ammonium aluminium hydrides have greater hydrolytic stability than the lithium salt the tetramethylammonium aluminium hydride is hydrolysed slowly in dilute aqueous acid and more lipophilic ammonium salts are more stable [4, 5]. 

GARSIDE, J. and AL-DlBOUNI, M. R. Ind. Eng. Chem. Proc. Des. Dev. 16 (1977) 206 Velodty-voidage relationships for fluidization and sedimentation in solid-liquid systems. 

McCune, L. K. and Wilhelm, R. H. Ind. Eng. Chem. 41 (1949) 1124. Mass and momentum transfer in solid-liquid system. Fixed and fluidized beds. 

If very small solute particles are dispersed in a solution, the solute concentration may exceed the normal equilibrium saturation value. The relationship between particle size and solubility first applied to solid-liquid systems by Ostwai.d120 may be expressed as ... 

The early, independent work of Starks, Markosa and Brandstrom from ca. 1965-1969, brought into focus with Starks classical paper in 1971, showed PTC to be potent and versatile synthetic tool.[1-4] Since that time, the well-documented investigations of PTC have been massive and vigorous.[5-7] In polymer chemistry PTC was effectively exploited first in anionic addition polymerization and more recently has been extended to condensation polymerization.[5,8-9] However, until a very few years ago, the use of solid-liquid PTC systems in polycondensation has for the most part escaped this intensive scrutiny. Consequently, some time ago we began a rather broad study into the use of solid-liquid PTC to effect polycondensations.[10]... 

The other approach called upon phase-transfer catalysis (31). The potassium salt of 2,5-furandicarboxylic acid 11a was treated with primary aliphatic dihalides in a typical solid/liquid system in the presence of a crown ether. The resulting furanic-aliphatic polyesters had molecular weights of... 

Sebti S, Foucaud A (1986) Anionic activation by fluoride ion in solid-liquid systems synthesis of 3(2H)-furanones and 2 (5H)-fmanones. Tetrahedron 42 1361-1367... 

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