SURFACE-PROPERTIES OF RIPIDOLITE AND BEIDELLITE CLAYS MODIFIED BY HIGH-ENERGY BALL-MILLING

The effects of physical disintegration (high-energy bail-milling) on t he surface properties (specific surface area and cation-exchange capac ity) of beidellite and ripidolite are presented and discussed. The mil ling caused considerable changes in the morphology of the clay, as sho wn by SEM and surface properties, followed by loss of crystallinity as shown by X-ray diffraction of the treated clay minerals. The transfor mation of the crystalline into the amorphous phase takes place directl y without the formation of intermediate solids different from the star ting crystalline and the resulting amorphous phase. Major changes in s pecific 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 mi n of milling. (C) 1997 Elsevier Science B.V.