抄録
The layer charge characteristics of thirteen samples of montmorillonites occurred in Tertiary sediments of Miocene age in southeastern Korea were determined. The layer charge (cation density) lies between the limits 0.46 to 0.25 per half unit cell and 7 or 8 different classes were observed in the majority of the samples. All samples show heterogeneous charge distribution. The average layer charge calculated from n-alkylammonium method varied 0.30 to 0.38 per half unit cell which is equivalent to cation exchange capacity of 80-101 meq./100g.
Measured CECs by AgTu method were always larger than calculated CEC from average charge density by n-alkylammonium method by 13-29 percent. This difference can be assigned to other factor, the most likely being broken bond effect on crystal edge and systematic error in alkylammonium method. The relationship between CEC from structural formulae and n-alkylammonium method with AgTu CEC was considered. It suggests that calculated CEC from the structural formulae of relatively impure montmorillonites based on conventional chemical analyses are probably more subject to error than those derived from the n-alkylammonium method.
