Montmorillonite curved particles

Sometimes, however, a comparison between the adsorption branch and the desorption branch may lead to a conclusion about the shape of the capillaries. An adsorption branch which has no inflexion point and gives a sharp rise only for relative pressures close to unity, combined with a desorption branch showing a definite inflexion point at medium values of relative pressures, indicates fissure-shaped capillaries (68). Hysteresis curves of this form are, for example, found with a lomerations which consist of disk- or plate-shaped particles, such as montmorillonites, and indeed hysteresis curves published by Barrer and MacLeod (59) show this behavior. Similar curves are found with the dehydration products of many well-crystallized metal oxide hydrates, such as those of the aluminum hydrates (gibbsite, bayerite, boehmite, and diaspora) (60). 

Figure 3.3 Schematic of curved montmorillonite particles (reproduced from Ref [8]).

DMDHT-modified montmorillonite clay is supplied in an agglomerate form. The basic process involves drying and grinding the modified organoclay. Air classification is recommended to remove large particles in the milled products. A typical particle size distribution curve is shown in Figure 7.3. The mean particle size is normally in the range of 15-25 tim. Top size (99%) should be less than 60 trm. 

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