The Effect of Sodium Hydroxide upon the Electrodeposition of Electrodialyzed Kaolin

Abstract

Fractions of electrodialyzed Georgia kaolin of definite particle‐size range were prepared by centrifugation and employed to make suspensions for obtaining pH titration curves with as base. Using the same partly neutralized suspensions from the pH measurements, the corresponding yield in g./coulomb upon electrodeposition was determined.Additional evidence was obtained that clay acts similarly to a weak monobasic acid upon titration, and that the following hyperbolic relation holds approximately for the yield upon electrodeposition at any pH: .A simple mathematical explanation of this relation is presented, based upon the Henderson‐Hasselbalch equation for the titration of weak acids.The cell vessel used for electrodeposition constituted the metal anode in order to afford an even deposit of cylindrical shape, which could be handled with minimum loss. The yield of clay varied with the kind of metal employed as anode. Most of the experiments were performed using silver, which gave maximum yield of the various metals tried. This suggests the advantage of silver‐plating anode equipment for the electrophoresis of clay.