Surface properties of ripidolite and beidellite clays modified by high-energy ball milling

The effects of physical disintegration (high-energy ball-milling) on the surface properties (specific surface area and cation-exchange capacity) of beidellite and ripidolite are presented and discussed. The milling caused considerable changes in the morphology of the clay, as shown by SEM and surface properties, followed by loss of crystallinity as shown by X-ray diffraction of the treated clay minerals. The transformation of the crystalline into the amorphous phase takes place directly without the formation of intermediate solids different from the starting crystalline and the resulting amorphous phase. Major changes in specific surface area and cation-exchange capacity were produced after 6 min of milling in beidellite and ripidolite clays, with both samples becoming similar after 30 min and maintaining such a state for 300 min of milling.