Acid-base properties of ca-montmorillonite from benavila region (Portugal) [Propriedades ácido-base da montmorilonite cálcica da região de benavila (Portugal)]

• Type: Article in International Scientific Journal
• Date: 2014

Authors

Guimaraes, V (Author) Other; Bobos, I (Author) FCUP; Rocha, F (Author) Other

Journal

Title: Comunicações Geológicas

Vol. 101

Pages: 791-794

ISSN: 0873-948X

Publisher: LNEG - Laboratório Nacional de Energia e Geologia

Indexing

ISI Web of Knowledge

Scopus - 0 Citations

Scientific classification

CORDIS: Natural sciences

FOS: Natural sciences

Associated Projects

KADRWaste - Estudo de Mecanismos e Cinética de Adsorção em Geomateriais e sua caracterização estrutural: implicações para os processos de atenuação natural da contaminação em metais pesados e confinamento de resíduos radioactivos - KADRWaste

Other information

Authenticus ID: P-00G-KA2

Abstract (EN): Montmorillonite is a dioctahedral (2:1) phyllosilicate mineral that plays an important role in many industrial and environment applications. Due to their peculiar physicochemical properties, mainly controlled by electrostatic interactions, the study of the acid-base properties of this material has been a subject of great importance in the last years. Thus, the understanding of the surface charge variation of montmorillonite, in order to obtain a better control of their physicochemical properties, become crucial. The main goal of this research is to study the surface properties of montmorillonite, through the acid-base titrations of its suspension, under different conditions of ionic strength ([NaCl]=0.01M and [NaCl]=0.1M). The titration data was interpreted by surface complexation models (NEM and CCM) taking into account an ideal behavior of the surface species, where the electrostatic interactions are ignored (NEM), and the presence of an electrical double layer (EDL) at the mineral-water interface where the electrostatic terms are involved (CCM). The results show that 6 different species are involved on the protonation and deprotonation of surface sites: two acidic species (strong-SiOH<inf>2</inf> + and weak-AlOH<inf>2</inf> +), two neutral species (SiOH and AlOH) and two basic species (weak-SiO- and strong-AlO-). The surface parameters obtained by the two models (NEM and CCM) are close to the same. However, it was concluded that the electrostatic influence become more significant as pH increases. © 2014, LNEG ¿ Laboratório Nacional de Geologia e Energia IP.

Language: English

Type (Professor's evaluation): Scientific