An inverse gas chromatography study of crystalline and amorphous silicas

Abstract The surface properties of silicas of various origins were measured by inverse gas chromatography. Amorphous silicas (in this case fumed and precipitated silicas) and crystalline silicic acid, which was prepared from Na-magadiite by acid treatment, were employed. As determined by inverse gas chromatography, the value of the dispersive component of the surface energy of the crystalline silicic acid is higher than that of the amorphous silicas, because of the possibility of a partial adsorption of alkane chains between the layers of this silica. Moreover, the injection of different bulky steric probes allows the evaluation of the silica nanorugosity. Concerning the H-magadiite, the more the probes are branched, the less they are adsorbed on the surface layer, demonstrating a size exclusion effect.