Rectorite interlayer cations

It has been previously reported that the structure of interstratified clays (such as rectorite) consists of a combination of mica-(nonexpandable) and smectite- (expandable) type layers. The mica layers are more probably Na-paragonite while the smectite layers are of the montmorillonite or beidellite type (3, 11-13). For mica-like layers, the most typical interlayer spacing is equal to 9.6A while it is of 9.5A for the smectite-like layers, see Figure 6-2. However, these d-values may change depending on the nature of the interlayer cations... 

Although there is a fairly good agreement between the Si content in the parent clay measured by AA and by EDS, the pillared rectorite EDS gives lower Si values than AA, as in Table 6-1. The presence of bulky Alu-clusters changes the composition on the clay silicate layers and could prevent the accurate detection of all of the Si present on the clay crystal surfaces. The pillaring reaction removes most of the Na-ions from the crystal surfaces however, residual Mg-ions are still present. Table 6-1. The increased Al Oj content in the expanded rectorite represents that portion of the Alu-cations retained as pillars in the clay interlayer space, see Table 6-1. 

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