Cation fixation smectites

Another type of reaction that responds to WD cycles is the fixation of K and NH4 ions by smectite (3-7). The fixation of K in smectite has been studied extensively by soil scientists because of its effect on the availability of plant nutrients. The reaction also decreases smectite s ability to swell, decreases its cation exchange capacity (CEC), and modifies its BrjSnsted acidity. Therefore, an understanding of this phenomenon is applicable to many fields of study that are concerned with swelling clays, fields such as soil fertility, soil mechanics, waste disposal, clay catalysis, and the geochemistry of ground and surface waters. 

In order to determine the structural factors, concerning host clays, which improve on the catalytic efficiency of pillared clay by the fixation of cations, the following were chosen for comparison with TSM montmorillonite (as smectite, having less of a layer charge than TSM, but an octahedral vacancy like TSM) and taeniolite (as mica, having the same layer charge as TSM, but no octahedral vacancy, unlike TSM). Table 14-2 shows the catalytic activities for cumene... 

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