THE EFFECT OF IRON OXIDE IMPURITIES ON THE POSITIVE AND NEGATIVE ADSORPTION OF CHLORIDE BY KAOLINITES ¹

Abstract

Summary In the past, the effect of iron‐oxide impurities in kaolinites has been ignored when studying properties such as edge‐charge and Cl − adsorption. In this investigation, iron oxides were found to have a marked effect on the adsorption of Cl − by kaolinite. Cl − was positively adsorbed by some kaolinites at high pH values indicating that positive charges were present under alkaline conditions. A large part of this positive adsorption of Cl − was due to the iron oxide in the samples. The presence of small amounts of iron oxides gave rise to large errors in the measurement of edge‐charge on kaolinite. After deferrification, reasonable results were obtained.