Consideration of surface area and crystallinity of Kaolinite as factors in its base exchange capacity

With a view to study the influence of surface area and crystallinity of kaolinitic on its 'bec', the base exchange capacities of three kaolinitic clays were compared with their surface areas as determined by low temperature argon adsorption and crystallinity as indicated by their X-ray difractograms in the region 16°C-43°C 2q using CmKa radiation coupled with their differential thermal curves. The results indicate that even though there is correlation between 'bec' and crystallinity of kaolinite in the different clays, no relation is observed between surface area and 'bec' of the different clays. It is considered that correlation may exist with surface area and base exchange due to broken bonds within the same clay but it may not hold with different clays due to some changes in the mineralogical composition and presence of minerals like tubular halloysite which can permit argon entry within the tubes and contribute to internal surface area also. (Dr. P. Prabhakaram, Scientist, National Metallurgical Laboratory, Jamshedpur)