Clay minerals occur widely in nature and play a very important role in agriculture, mineral recovery and chemical manufacturing.
Among the many properties which affect clay behaviour, water binding and ion exchanging appear to be the most important. The
study of the cation exchange capacity of soils is of great theoretical and practical importance since the CEC determines in
many ways the behavior of nutrients, chemical amendments, and many toxic compounds entering the sols. Sorption interactions
with montmorillonite and other clay minerals in soils are potantially important mechanisms for attenuating the mobility of
heavy metal cations through the subsurface environment. In this work the cation exchange capacity (CEC) of montmorillonite
from west Anatolia, and sorptions with montmorillonite for attenuating the mobility of uranium were studied. The CEC value
was found to be 77 meq/100 g montmorillonite. The relative importance of test parameters e.g., contact time, particle size,
pH and U(+6) aqueous speciation was determined. The results show that sorption on montmorillonite is a funtion of pH depending
strongly on the aqueous U(+6) species. It reaches a maximum at near neutral pH(pH}7). At low and at high pH solutions the
sorption values of uranium are poor. These sorption values were attributed to the formation of aqueous U(+6) carbonate complexes
in alkaline conditions and the ionexchange process between UO2+2 species and interlayer cations on montmorillonite in acidic solutions.