| Texto completo | |
| Autor(es): |
Silva, Bruna Nadia N.
;
Pastore, Heloise O.
;
Leitao, Alexandre A.
Número total de Autores: 3
|
| Tipo de documento: | Artigo Científico |
| Fonte: | APPLIED CLAY SCIENCE; v. 231, p. 9-pg., 2023-01-03. |
| Resumo | |
This work reports a detailed study of the K-, Mg-, and Ca-magadiites simulated from the structure of Namagadiite. Several molecular geometries were tested in each model, and the results showed a hydration sphere similar to the initial sodium material. In the interlayer region, Na- and K-magadiites showed longer coordinated bond lengths, leading to higher basal spacing values (15.43 angstrom and 15.71 angstrom, respectively). Solids containing divalent cations presented the strongest H-bonds between the water molecules and the layers, also reinforced by the charge density distribution. Different stretching (3000 - 3800 cm(-1)) and bending (1500 - 1750 cm(-1)) of water molecules were identified in the vibrational analysis, and the simulated-experimental comparison of spectra suggested that dehydrated samples adsorb water molecules initially in axial positions and, later, in equatorial positions. Thermodynamics analysis at 298.15 K confirmed the difficulty of obtaining complete sodium to potassium exchanged forms (Delta G = 126.03 kJ.mol(-1)), while Ca-magadiite can be formed spontaneously (Delta G = -190.86 kJ.mol(-1)). (AU) | |
| Processo FAPESP: | 14/06942-0 - Sólidos lamelares nanoestruturados como catalisadores ácidos, básicos e redox |
| Beneficiário: | Heloise de Oliveira Pastore |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |