Particle cleavage

Particle cleavage (erosion) Freely moving particles, which are carried in an intermediate medium between the base and counter body cause the wear (three-body abrasion). 

Cation A positively charged particle or ion. Channeling Cleavage and furrowing of the bed due to faulty operational procedure, in which the solution being treated follows the path of least resistance, runs through these furrows, and fails to contact active groups in other parts of the bed. 

Recommended model particle systems are enzymes immobilised on carriers ([27,44,45,47,49]), oil/water/surfactant or solvent/water/surfactant emulsions ([27, 44, 45] or [71, 72]) and a certain clay/polymer floccular system ([27, 42-52]), which have proved suitable in numerous tests. The enzyme resin described in [27,44,47] (acylase immobilised on an ion-exchanger) is used on an industrial scale for the cleavage of Penicillin G and is therefore also a biological material system. In Table 3 are given some data to model particle systems. 

Fig.6. Photocatalytic cleavage of H2S over a platinized composite sulfide semiconductor particle with a heterojunction.

Hydrogenolysis of butane was used to study the catalysis of the RhPt particles in mesoporous silica. This is a test reaction of reforming of alkanes in oil refinery, and methane, ethane, and propane are formed by the cleavage of terminal or central C-C bond (Scheme 1). 

The manner in which a particle fractures depends on (i) the nature of the particle and (ii) the manner in which the fracture force is applied. A number of terms have been used to describe the different mechanisms of single particle fracture. The different terms considered here are abrasion, cleavage, shatter, and chipping. It may be pointed out that in practice these events do not occur in isolation. Real breakage involves a combination of these processes, with the proportions changing, depending on the equipment, and on the manner each particle is stressed within it. 

Cleavage fracture is said to take place when the applied energy is just sufficient to load a few regions of the particle to the point of fracture. Only a few particles result, and their size is comparatively close to that of the original particle. This situation typically arises under conditions of slow compression where fracture immediately relieves the loading on the particle. 

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