Surface Reactions of Clay Minerals

The effects of particle size of various clay minerals on the properties of cation exchange capacity, ethylene glycol retention, and gas adsorption were determined. The particle size of the clays was varied by limited ball‐milling procedures. Kind of exchangeable cation did not greatly affect the ethylene glycol retention by non‐expanding clays, but cations capable of undergoing fixation did affect the retention by montmorillonite. This indicated the effect of exchangeable cations, capable of fixation reactions, was to prevent solvation of the inner‐layer spaces of montmorillonite rather than a differential association between the cations and ethylene glycol. Ethylene glycol retention was not found to be a function of cation exchange capacity. Specific surface figures determined by ethylene glycol retention and by B.E.T. analysis, using ammonia adsorption, agreed fairly well for non‐expanding clay minerals but differed considerably for montmorillonite.