Fourier Transform Infrared, Solid-State Nuclear Magnetic Resonance, and X-Ray Diffraction Studies of Natural and Acid-Treated Bentonites from Turkey

Abstract

The Fourier transform infrared (FT-IR) technique is widely used to distinguish structural properties and to derive information about structural changes following the chemical modification of clays in different conditions. Natural and acid-treated bentonites with HCl from Turkey were investigated by FT-IR between the region of 4000 and 400 cm-1 and the obtained results were supported by 29Si, 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) and X-ray diffraction (XRD) measurement techniques. Effects of acid treatment were monitored by following the destruction of the original bentonite sample upon the acid treatment with different (6 hr, 12 hr, and 24 hr) acid exposure times. Following 24-hr acid treatment, the tetrahedral Si4+ structure was not fully collapsed but most of it turns into three-dimensional SiO2 impurity.