Aggregation Agglomeration

Agglomeration Aggregation Binder Carbon black Dust... 

Organic compounds are subject to agglomeration/aggregation effects and, even worse, to oiling out. All of these problems can potentially result in undesired trapping of solvent and/or impurities in the final crystal. Oiling out, of course, can completely inhibit the formation of a crystalline phase, resulting in a gum or an amorphous solid. These phenomena are discussed qualitatively in Chapter 5. 

A substantial-sized subgroup of those compounds which do not exhibit typical crystal growth, in which a repeated lattice grouping or crystal structure, is so difficult to achieve that the compound resembles a Uquid as it emerges from solution. This is the phenomenon of oiling out, which is often accompanied by the additional compheation of agglomeration/ aggregation. 

A high degree of supersaturation can also cause oiling out and/or enhance agglomeration /aggregation of the developing nuclei, as well as cause occlusion of impurities and/or solvent in the crystals (see Section 5.4). 

Hollow to porous to void Ifee solid Singular, agglomerates, aggregates, flocculated materials... 

Randolph [95] and Randolph and Larson [96], on the other hand, formulated a generic population balance model based on the generalized continuum mechanical framework. Their main concern was solid particle crystallization, nucleation, growth, agglomeration/aggregation and breakage. 

The fundamental derivation of the population balance equation is considered general and not limited to describe gas-liquid dispersions. However, to employ the general population balance framework to model other particulate systems like solid particles and droplets appropriate kernels are required for the particle growth, agglomeration/aggregation/coalescence and breakage processes. Many droplet and solid particle closures are presented elsewhere (e.g., [96, 122, 25, 117, 75, 76, 46]). 

A fairly general framework has been formulated for the source terms considering particle breakage, fluid particle coalescence, solid particle agglomeration/aggregation and similar processes (e.g., [109, 80, 81, 37, 114, 43, 25, 94]). Detailed discussions of the particle breakage and coalescence modeling and the mathematical properties of the constitutive equations can be found in the papers by Barrow [4], Laurencot and Mischler [64, 65]. 

A number of similar individual entities that occur together. (See also accretion, agglomerate, aggregation.) The growing together of primary a lomerates to form larger entities. (See also satellites formation.)... 

Fig. 6.11-10 Re-agglomeration (aggregation) of electrostatically dispersed Si02, Aerosil 0X50 (manufacturer Degussa) left) original sample ...

The process of growth or enlargement by a gradual BUILDUP, such as increase by external addition or accumulation, for example by ADHESION of external parts or PARTI-GLES. (See also AGGLOMERATION, AGGREGATION, BUILD-UP)... 

To collect or gather into a mass. (See also AGGLOMERATE) A group, body, or mass composed of many distinct parts or individuals the collection of units or parts into a mass or whole the condition of so collected. (See also AGGLOMERATE, AGGREGATE, CLUSTER, AGGLOMERATION, ACCRETION, BUILD-UP)... 

A number of similar individual entities that occur together. See also ACCRETION, AGGLOMERATE, AGGREGATION)... 

MNPs in simple imidazolium ILs tend to agglomerate/aggregate after some reactions such as hydrogenation of aromatic compounds or ketones. However, more stable catalytic systems in ILs can be obtained by the addition of ligand or polymeric stabilizers such as poly[(N-vinyl-2-pyrrolidone)-co-(l-vinyl-3-aIkylimidazo-lium hahde)] copolymers [115], poly(N-vinyl-2-pyrrolidone) (PVP) [116], carbon, montmoriUonite (MMT) or mesoporous SBA-15 [117, 118]. The NP/IL/extra-stabilizer combination usually exhibits an excellent synergistic effect that enhances the activity and durability of the catalyst for the hydrogenation of olefins. Another... 

Small particles in liquid suspension have a tendency to cluster together. Such terms as agglomeration , aggregation , coagulation and flocculation have all been applied in this area, although without any generally accepted rules of definition. For simplicity, therefore, the term agglomeration will be used exclusively in this section. 

The equation = 3.67 G x is only valid when all MSMPR assumptions are fulfilled (besides other no attrition and no agglomeration). However, in the case a < 0.1 the mean crystal size L q and especially the maximum ciystal size with max 2 Z50 is controlled by attrition, see Fig. 8.5-1 below. On the other hand, agglomeration can be the dominant process parameter for a > 10. Nanocrystals can only be produced if the relative supersaturation is high with the result of high rates of activated nucleation and by the avoidance of agglomeration. Aggregates which are formed under low or zero supersaturation do not possess crystalline bridges and can be redispersed. 

Fractal aggregate, fractal agglomerate aggregates or agglomerates with a non-uniform distribution of the constiment particles, which typically coincides with a very porous, branch-like morphology fractal aggregates are characterised by a power-law decrease of the pair-correlation density function g(v) (Eq. (4.8)) and a power-law relationship between mass and size (Eq. (4.9)), in which the exponent is less than the Euclidean dimension fractal aggregates are not ideal fractal objects, but rather obey the fractal relationships only in a statistical sense (cf. Sect. 4.2.1). 

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