Expansibility of vermiculite (Santa Luzia, Brazil) irradiated with microwave

The effect of microwave heating on the expansion of vermiculite was studied at a level of 700 W for 4 min exposure time and compared with raw vermiculite. In this study, the characterization of vermiculite from a mine in the northeast region of Brazil was performed using thermogravimetry, N₂-adsorption, cation exchange capacity, X-ray powder diffraction (XRD), infrared (IR) spectroscopy, X-ray fluorescence spectroscopy (XRF), and scanning electron microscopy (SEM). Following the microwave heating, the vermiculite was characterized using XRD, IR spectroscopy, and SEM. Microwave irradiation of the vermiculite sample caused structural changes such as loss of crystallinity and disorder, as revealed by the XRD patterns, but did not cause expansion. Results from SEM and IR spectroscopy showed that the microwave heating did not cause profound alterations to the morphology, clay structure, and chemical composition of the vermiculite.

Keywords:
vermiculite; microwave heating; irradiation; expansibility