Variation of interlayer binding energy of muscovite in its swelling

Abstract

The interlayer binding energy of natural muscovite after thermal and ionic exchange treatments has been investigated using X-ray diffraction, molecular dynamics simulation and one-dimensional Patterson function. The results showed that the interlayer binding energy was reduced to less than 1/30th of its strength subsequent to thermal and ionic exchange treatments. The decrease of the binding strength after thermal treatment might be due to the modification of atomic positions within the layer and a slight increase of interlayer spacing. A dramatic decrease of the binding strength from 110.05kJ/mol to 19.09kJ/mol was observed after the LiNO3 treatment. The mechanism might be explained by a combination of an increase of interlayer spacing and Li+ immersion into the layers. In addition, interlayer spacing was increased to 3nm when octadecyl trimethyl ammonium ion (OTA+) intercalation was used, resulting in the interlayer binding energy approaching 0kJ/mol.