Experimental illitization of smectite in a K-rich solution

The illitization of a K-smectite in 0.5 molal KCl at 300 degrees C and vapour saturation was studied to determine the nature of layers in interstratified run products formed in solutions supposed to favour the formation of illite layers. The percentage of illite layers in mixed-layer clays was determined by XRD and IR spectroscopy (on NH (super +) (sub 4) saturated experimental products). Discrepancies between the Si contents of mixed-layer clays by EPMA and the percentage of supposed illite layers estimated by different techniques confirm the existence of non (glycol) expandable dehydrated smectite layers. IR spectroscopy indicates that some of these layers have not fixed interlayer K (super +) ions and are still exchangeable (with NH (super +) (sub 4) ) whereas others cannot exchange their interlayer cation; this behaviour is probably related to the layer charge deficiency and its structural location in the smectite layers. The amounts of dissolved smectite layers and crystallized non-expandable layers (illite, dehydrated smectite) in newly formed interstratified clays increase with time.