Modification of the Kaolinite Hydroxyl Surfaces through Intercalation with Potassium Acetate under Pressure

Abstract

Kaolinite hydroxyl surfaces have been modified upon intercalation with potassium acetate under a range of conditions. Modification is observed by changes in the hydroxyl stretching region using Raman and infrared spectroscopy. Upon the intercalation of low defect kaolinite with potassium acetate under a pressure of 20 bars and 220°C, the Raman spectra showed additional bands at 3590, 3603, and 3609 cm−1. The DRIFT spectra of this intercalate showed new bands at 3595 and 3605 cm−1. These bands are attributed to the inner surface hydroxyls hydrogen bonded to the acetate anion. Intercalation under 20 bars pressure at 220°C caused the differentiation of the inner surface hydroxyl groups, resulting in these additional bands. By using milder conditions of 2 bars and at 120°C, additional Raman bands were found at 3592, 3600, and 3606 cm−1. If the kaolinite was intercalated at 1 bar and 100°C, a new broad Raman band was found at 3605 cm−1. It is proposed that the effect of intercalation of the low defect kaolinite under pressure caused the kaolinite to become disordered and this disordering was dependent upon the temperature of intercalation.