Local Cuban bentonite clay: composition, structure and textural characterization

QUERO-JIMÉNEZ, PEDRO CÉSAR; ARIAS FELIPE, LESTER ALEJANDRO; PRIETO GARCÍA, JULIO OMAR; JORGE RODRÍGUEZ, MARÍA ELISA; DE LA TORRE LÓPEZ, JORGE BASILIO; MONTENEGRO, OSVALDO NORMAN; MOLINA RUÍZ, REINALDO; TISCORNIA, INÉS SILVIA

ANDEAN GEOLOGY

SERVICIO NACIONAL GEOLOGIA MINERVA

Año: 2021 vol. 48

0718-7092

The physic and chemical characterization of the bentonite clay from the Chiqui Gómez deposit, central Cuba, (Cuban bentonite clay) shows that it is mainly constituted by sodium montmorillonite (>90%), with a structural formula for one-layer unit determined as (Na3.99Al0.01)(Al1.11Fe3+0.49Mg0.18Ti0.07)(Ca0.24Na0.15K0.01)O10(OH)2. The Cuban bentonite clay has a specific surface area of 80m2g-1, a pore volume of about 0.0776 cm3g-1, 61 % porosity and both N2 adsorption?desorption isotherms exhibited a hysteresis loop of IV type. The thermogravimetric analyses (TGA) of studied mineral presents the first endothermic peak, characteristic of montmorillonite, in 48.1 ºC and others less accentuated (80.8, 94.0, 119.8 ºC) characteristic of sodium montmorillonite, that corresponds to the loss of water, and can be extended up to 250 ºC. The FT-IR spectra showed the existence of Si-OH, Al-Al-OH, Al-Fe-OH, Al-Mg-OH and Si-O-Si functional groups in all clay samples, bands between 1120 and 461 cm-1 correspond to phyllosilicate structures and OH stretching vibrations were observed. pH at the point of zero charge (pHPZC) obtained has a value of 8.1, which allows montmorillonite to be classified as basic.