ScienceAsia 7 (1981): 100-109 |doi: 10.2306/scienceasia1513-1874.1981.07.100

THE CATION EXCHANGE CAPACITY OF SOME KAOLIN MINERALS

N. CHAIKUM,^a N. SOOPPIPATT^a and R.M. CARR^b

ABSTRACT: The variation of the carion exchange capacity (CEC) of some kaolin minerals with the nature of the exchanging cation, temperature, and pH has been studied. Cation exchange properties of kaolins originate largely from isomorphous substitution and pH- dependent surface charges but the exchange reaction was complicated by the presence of impurities on the clay surfaces and the tendency of kaolins to form intercalation complexes. The CEC apparenrly increases with increasing pH, halloysite showing a stronger pH-dependence than kaolinite. High-temperature studies were limited to temperatures below 100 ^oC. The CEC's for all halloysites and a kaolinite were less than 10 meq/100 g and the temperature effects were small and rather unpredictable.

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a Department of Chemistry, Mahidol University, Rama 6 Road, Bangkok 4, Thailand.
b Department of Chemistry, Otago University, Dunedin, New Zealand.

Received 23 July 1981