SURFACE CHEMISTRY OF KAOLINITE .I. SURFACE LEACHING

Aqueous suspensions of kaolinite from Mt. Egerton, Victoria, have been leached at pH 2.25 and 6.0. More ions, in particular aluminium, than predicted from the published cation-exchange capacity have been detected in the leachate. An activation energy of 5 kcal/mole has been calculated for this process of surface leaching. Using a supporting electrolyte of, for example, 10‒4M KCl, the electrophoretic mobility of leached and raw clay has been examined as a function of pH, and differences in mobility have been correlated with aluminium removal from the clay surface. © 1968 CSIRO. All rights reserved.