Degradation Characteristics of Hydrogen Montmorillonites

The nature and extent of degradation of three hydrogen montmorillonites differing in their chemical composition owing to isomorphous substitution was evident from their lattices at the edges and planar surfaces os indicated by X-ray diffraction, differential thermal, chemical and electrometric analyses and determination of free oxides. There is marked colour change, appreciable lowering of pH, and loss of dispersive character and formation of flocs, often of a thixotropic gel. There is an increase in the free oxide contents of the montmorillonites as well as the water holding capacities. Considerable amounts of aluminium, iron, magnesium and other octahedral cations are removed from the lattices followed by redistribution of electrical charges in the tetrahedral and octahedral layers. They also exhibit a gradual change from weak acid to strong acid character with decrease in cation exchange capacities. The three hydrogen montmorillonites differ widely in the degradation of their lattices.