Sorption of Sr on Montmorillonite clays: theoretical and experimental study

DÍAZ DE ROSA V.; GIL REBAZA, ARLES; MONTES, MARIA LUCIANA; M. TAYLOR; R. E. ALONSO

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2022 vol. 592 p. 153146 - 153154

0169-4332

Montmorillonite (MMT) is a clay mineral widely used to remove pollutants from wastewater due to its cation-exchange capacity and high surface area. In this work, the sorption of Sr on MMT was analyzed combining an experimental and theoretical approach. Sr sorption on natural and synthetic Na-MMT was studied, characterizing the sorbent material before and after Sr incorporation by X-ray diffraction (XRD) on semi-oriented samples. Also, ab-initio calculations have been performed in order to investigate the sorption capacity of the clay, the effect of the hydration of Sr atoms and the influence of the van der Waals interaction (vdW). The results indicate that Sr incorporation increases the interlayer space of the MMT d001. This increase is related with the cationic exchange of Na+ by Sr+ , which presents different ionic radii, but also with the hydration of the Sr atom and the relative humidity. NMR parameters were calculated at different atomic sites and compared with the experimental chemical shift and electric field gradient for each atom. The calculated chemical shift for the Sr atom corresponds to the expected range for atomic coordination n=6. Since there is no experimental data available for VZZ at the Sr site, our obtained theoretical value stands as a prediction.