Characterization of porous silica prepared from mechanically amorphized kaolinite by selective leaching

The structure of leached products from mechanically amorphized kaolinite wa s investigated by various techniques. The Si-29 MAS NMR spectrum of the lea ched products showed peaks at - 102 and - 111 ppm, assigned to the silanol groups and the three-dimensional silica framework, respectively. The microp ore size distribution calculated by the Horvath-Kawazoe method, using Ar ga s as the adsorbate, showed a maximum at 0.9 nm, suggesting slit-shaped pore s formed between the layers of the mechanically destroyed kaolinite. Longer leaching times reduce the number of micropores due to a condensation react ion. (C) 2001 Elsevier Science B.V. All rights reserved.