Heterocoagulation: dependence of dispersion particles ζ -potentials limit values adequate to their stability
Abstract
A number of technological processes occur in 2-or 3-phase disperse systems. The rate of these processes is determined by sorption processes. For substances insoluble and slightly soluble in the continuous liquid phase, sorption processes are complicated by substances mass transfer between the particles of disperse phase occurs through the contact surface of disperse phases that involves particles coagulation
Purpose of the work is to estimate the critical distance between the disperse particles and the ratio of the critical values of the ζ -potentials of the particles having different potentials of the value corresponding to the rapid coagulation boundary conditions. We used the methods of theoretical modeling and mathematical
analysis. A theoretical analysis of heterocoagulation particular case – stability of the disperse particles of the same nature but of different size (diameters) and electrokinetic potential ( ζ -potential) values is conducted.
Spherical particles which size is significantly larger than electrical double layer δ diffuse part thickness are considered.
Critical parameters estimations corresponding with rapid coagulation limiting conditions for the disperse particles of different ζ -potentials ζ ≠ζ2 are received: critical distance hcrbetween the nearest 1cr crpoints on the particles surface is determined by the ratio of their ζ -potentials critical values ζ ζ2 and of 1the electrical double layer diffuse part thickness critical value δ corresponding to the rapid coagulation
cr cr cr cr cr boundary conditions: hcr ≈δcr (1.042 + 0.102 exp ln(ζ1ζ 2 )), 0.16 ≤ζ ζ2 ≤ 6.2 ,1 R = 0.99 ; critical values of the ζ and ζ particles ζ -potentials are determined by the critical ζ 12 ζcrpotential value ( ), corresponding to the rapid coagulation boundary conditions of identical particles of the 2cr cr=cr crζ)1− (ζ1) 1where R2 is the accuracy of approximation. The data can be used for theoretical modeling and intensification of a number technological processes (chemical and microbiological synthesis, isolation and purification of target products, waste treatment), taking place in disperse systems which particles have different ζ -potential values. In this way, ζcr
knowing the critical ζ -potential ( ) value corresponding to the identical particles rapid coagulation boundary conditions, for this type of system we can calculate the dependence of the pair of particles ζ cr cr potentials critical values ( ζ ≠ζ ) corresponding to the threshold of their relative stability.
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References
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