Perikinetic agglomeration

Perikinetic agglomeration applies to a monodisperse suspension and can be represented by a second-order rate law ... 

TJhe aggregation of particles in a colloidal dispersion proceeds in two distinct reaction steps. Particle transport leads to collisions between suspended colloids, and particle destabilization causes permanent contact between particles upon collision. Consequently, the rate of agglomeration is the product of the collision frequency as determined by conditions of the transport and the collision efficiency factor, the fraction of collisions leading to permanent contact, which is determined by conditions of the destabilization step (2). Particle transport occurs either by Brownian motion (perikinetic) or because of velocity gradients in the suspending medium (orthokinetic). Transport is characterized by physical parame-... 

The overall rate of agglomeration of any suspension, that is prepared experimentally and consists of small and large colloids, is obtained by adding the expressions derived for perikinetic and orthokinetic coagulation (Equations 2 and 5) ... 

From a comparison of the two collision frequency terms, described in detail in the Equations 3 and 6, one obtains the relative contributions of the perikinetic and orthokinetic transport to the total particle agglomeration. The ratio is a function of the radius of the colloid, r, and the absolute value of the velocity gradient du/dz ... 

Considering that the mechanism of flocculation or agglomeration of a pond is perikinetic in nature (see Eq. 9.17), using the data given below, graphically estimate kp and the time needed for half of the particles to flocculate. ... 

Destabilization of particles or colloid substances in water as well as their subsequent coagulation and separation are determined by chemical parameters of solution such as pH, concentration, and type of both colloid and coagulant etc. Efficiency of collisions leading to particle agglomeration in pe ikinetic coagulation is expressed by the collision efficiency factor (Up) under perikinetic conditions [ 1,2 ]. 

Perikinetic, where agglomeration takes place as a result of Brownian motion. The following equation was proposed for determining the collision rate of particles (78)... 

Both modes can occur in precipitation processes, but in a stirred precipitator orthokinetic agglomeration clearly predominates. From the Smoluchowski kinetic expressions for perikinetic and orthokinetic agglomeration it can be deduced (Sohnel and Mullin, 1991) that the relationship between agglomerate size D and time t may be expressed by... 

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