Monitoring, by inverse gas chromatography, of the variation of the surface energetic heterogeneity of ground muscovite samples

A layered mineral, like muscovite, is a good model of a heterogeneous solid because it presents two types of crystalline surfaces: basal and lateral surfaces. A convenient method for changing its degree of surface heterogeneity is to submit muscovite to a grinding process, creating new surfaces: either basal surfaces if the delamination of the crystal is the dominant process or lateral surfaces if comminution is prevalent. The aim of the present work is to demonstrate how inverse gas chromatography, combined with an original method of calculation of the adsorption energy distribution functions, is a very sensitive method to monitor the evolution of the surface heterogeneity of muscovite ground in the presence of different grinding additives such as glutaric acid (0.5% in aqueous solution) or potassium chloride (1 M in aqueous solution). It is shown that the latter favors the delamination of the muscovite crystal whereas the former induces the comminution of the crystal leading to an increase of lateral surfaces.