A brief review of the nature of the clay mineral montmorillonite affords a further 
insight into the absorption of complex organic cations. The silicate clay minerals includ- 
ing montmorillonite are described as having a layer-lattice structure in which one 
molecule is not distinct from another, but the minerals have a repeating pattern occurring 
in layers and building a platelike structure. The structure of montmorillonite is shown 
schematically in Figures 3 and 4. Each crystal layer consists of an aluminum sheet with 
a silica sheet above and below. The layer thickness is fixed. However, the spacing 
between layers varies between the limits of 3 and 24 A. Normally the interlayer spaces 
are occupied by water and inorganic cations such as Ht or Catt. When montmorillonite- 
organic cation complexes are formed these are replaced and the lattice spacing altered 
(see Figure 4). 
96-30 al 
66 AL 
BN-10716-X 
Figure 3,--Schematic representation of the structure of montmorillonite, 
Vi 
eee =Silica sheet 
IR 
=—Alumina sheet 
5.5 A iHR™{#.’'’—'] W$WW$W Wr rs 5c nen 
TTT 
[TLILTLTLTL TL. 
| | | 
BN-10715-X 
Figure 4,--Schematic representation showing molecular ions between silicate layers of montmorillonite, 
] 
| | 
“ul 
67 
