Comparative FT-IR study of structural modifications during acid treatment of dioctahedral smectites and hectorite

摘要

Seven dioctahedral smectites of various composition and one trioctahedral smectite (hectorite) were leached in the HCl under different treatment conditions. Hectorite is much more susceptible to acid attack than the dioctahedral smectites. The rate of smectite dissolution increases with increasing octahedral Mg or Fe content as well as with the treatment temperature and acid concentration. The mechanism of smectite dissolution in HCl is independent of layer composition. The final reaction product obtained from acid dissolution of both smectite types is a hydrous amorphous silica phase. FT-IR spectroscopy is a sensitive method for characterization of the starting mineral, identification of some admixtures, such as quartz or kaolinite, and can be useful to assist in controling the extent of acid dissolution. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 28]