A study on the intercalation and exfoliation of illite

Abstract

Illite particles were exfoliated from the illite-organics intercalation precursor in the ultrasound process. Four intercalating agents (glycerol, hydrazine hydrate, dimethyl sulfoxide, and urea) were selected to study the intercalation reaction for purified illite, thermal activated illite, and acidified illite and to prepare different illite-organics intercalation complexes. The resulting intercalation complexes and exfoliated illite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), the zeta potential test, the particle size test and thermogravimetry analysis (TG). XRD results showed that the thermal activation and subsequent acidification treatment to exchange K+ in the interlayer of illite with H+ is a necessary condition for organic intercalation. FTIR and TG analysis confirmed the intercalation of four intercalating agents into the interlayer of illite. During the high-temperature ultrasonic treatment, the organic molecules were deintercalated from the interlayers of illite-organics intercalation complexes, leading to the separation of the illite layers. The d001 diffraction of illite in XRD patterns became broad and weak after ultrasonic treatment; this indicated the random orientation of illite platelets. Particle size analysis showed the exfoliated illite (IUE) from the illite-urea intercalation complex possessed the smaller particle diameter. SEM and TEM observation showed the particle size of IUE is 0.5–4 μm with a layer thickness of approximately 200–300 nm. Moreover, the exfoliation of illite layers exposed more internal layers with negative charge, leading to the decrease of zeta potential.