Adhesion in Electrolyte Solutions

Influence of Cation Nature, Valence, and Concentration on Adhesion. As 

In Fig. VI.6 we show the adhesion number of quartz particles on a glass surface as a function of the concentration of electrolytes with different cation valences [12]. The adhesion number of glass particles on a glass surface is shown in Fig. VI.7 as a function of the applied detaching force, in solutions of KCl (curves 1 and 2), CaCU (curves T and 2 ), and AICI3 (curves l and 2 ) with concentrations of 0.01 and 0.001 mol/liter. It will be noted that, on the one hand, the adhesion drops off for all of the electrolytes with decreasing electrolyte concentration on the other hand, the lower the solution concentration, the more rapidly the adhesion drops off [77]. Also, for solutions with concentrations from 0.01 to 0.001 M, the adhesion increases with increasing valence of the cation. 

The adhesion number is related to the electrolyte concentration [12,15] by the following expression  

The adhesion of particles depends not only on the electrolyte concentration, but also on the cation valence, i.e., whether they are univalent, bivalent,or trivalent [77] this is particularly apparent for solutions with c = lO -lO mol/liter. With decreasing cation valence, particle detachment becomes easier. For example, with a detaching force of 2.7 10 dyn, 56% of the particles remain when the detachment is performed in a 10 mol/liter solution of KCl, in comparison with 88% in a solution of AICI3 of the same concentration. 

For more concentrated solutions (0.1 and 1 mol/liter) with the same detaching force, almost all of the particles remain on the dust-covered substrate. Hence, with solution concentrations above 0.1 mol/liter, it is impossible to determine the relationship between particle adhesive force and the nature of the electrolyte by use of the inclined-surface technique. 

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Sometimes the changes in particle adhesion in electrolyte solutions are associated with a change in magnitude of the f potential. The f potential, however, can serve only as an indirect index of the change in adhesive force since this potential is itself a function of the thickness of the diffuse layer of adsorbed ions. 

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