Effects of exchanged cation, acid treatment and high shear mechanical treatment on the swelling and the particle size distribution of vermiculite

The objective of the present work is the study of the effect of three different chemical treatments on the swelling and the particle size distribution of a vermiculite sample from of the State of Goiás, central-west Brazil, by using inorganic solutions of LiCl, NaCl, and HCl, accompanied by a high shear mechanical treatment. X-ray diffraction and X-ray fluorescence were used to characterize the as-received material. The effect of the chemical/mechanical treatment on the swelling and the particle size distribution of the vermiculite were investigated by Foster swelling test in water, cation exchange capacity, and particle size distribution by laser diffraction. Results showed an increase in swelling and a reduction in particle size for all the samples after the chemical treatments. The highest rates of swelling in water were obtained after the chemical treatment and the high shear homogenization process, following the order: HCl > LiCl > NaCl. These results stimulate further research exploring the acid treatment combined with a high-shear mechanical treatment to modify the characteristics of vermiculites, in order to produce high rates of dissociation/dispersion of vermiculite particles in water, thus broadening the potential applications for this material.