The Effect of Electrical Forces on the Stability of Colloidal Sols

Abstract

It is assumed that the stabilizing potential in a sol is not the potential at a distance t from the surface of the particle, (ζ), but the potential at a distance l, (λ). l is the distance from the solid surface at which a maximum in the potential energy curve determines the rate of coagulation, and λ is a constant for a given sol in states of equal stability. The quantities l—t and λ are evaluated from experimental data.

Coagulation of Hydrophobic Sols in Statu Nascendi. II. Effect of the Concentration of the Sol and of the Stabilizing Ion on the Coagulation of Silver Chloride, Silver Bromide, and Silver Iodide.

“…With the more concentrated sols of moderate or low charge density, the relative distribution of the stabilizing and coagulating ions seemingly has not reached the full corresponding state for ions of all valencies, the trivalent counter-ions being the last in approaching this state. As the quantitative criterion of this corresponding or isostable state (3,12) we may have the relation:/! = constant, where ft is the activity coefficient for the positive counter-ion at the critical concentration of coagulation.…”

“…(2) In the proportionately narrow region of low ionic concentrations, the increasing concentration of the stabilizing ion increases the coagulation value of the monovalent ion, decreases the coagulation value of the trivalent ion, and affects little the behavior of the bivalent ion. (3) The coagulation values for mono-, bi-, and trivalent ions decrease as the sols become more concentrated (from 0.00001 to 0.0010 M on the basis of the total amount of silver bromide). (4) As the concentration of the sol decreases, the coagulation value approaches the upper limit, firstly for monovalent ions, then for the bivalent, and finally for the trivalent ions.…”