Colloid perikinetic coagulation

Perikinetic Coagulation. The concentration of small silica colloids (Ludox LS d = 15 m/ ) used in these studies was between 0.18 gram/liter and 0.43 gram/liter (36.5 — 86.0 meter2/liter or 5.0-11.5 X 1013 par-ticles/ml.). The dispersion, contained in a spectrophometric cell, was... 

B) Relative colloid stability as a function of the total concentration of coagulant added, Ct, at constant pH—obtained from the measurement of perikinetic coagulation rates according to Equation 3. (Ludox LS = 0.3 gram/liter)... 

Perikinetic Coagulation. If colloidal particles are of such dimensions that they are subject to thermal motion, the transport of these particles is accomplished by this Brownian motion. Collisions occur when one particle enters the sphere of influence of another particle. The coagulation rate measuring the decrease in the concentration of particles with time, N (in numbers/ml.), of a nearly monodisperse suspension corresponds under these conditions to the rate law for a second order reaction (15) ... 

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 ]. 

The rate constant kp is given in terms of physical parameters (Boltzmann Constant KB, the absolute temperature T, and the absolute viscosity rj) that characterize these transport conditions. In the case of not completely destabilized colloids, when according to v. Smoluchowski so-called slow coagulation is observed, the rate constant contains in addition the collision efficiency factor, p, the fraction of collisions leading to permanent attachment under perikinetic conditions ... 

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) ... 

The rate of coagulation depends upon the collision frequency, which is controlled by physical parameters describing perikinetic or ortho-kinetic particle transport (temperature, velocity gradient, number concentration and dimension of colloidal particles), and the collision efficiency factor a measuring the extent of the particle destabilization which is primarily controlled by chemical parameters. 

The starting point in the above mentioned papers is a solution of colloidal particles which undergoes either a perikinetic or ortokinetic coagulation, or both. If the number euid size distribution of particles is known at the start of the coagulation, the number and size distribution of them can be calculated and determined at any later stage. The agreement between the experimental data and those calculated was good -sometimes excellent. 

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