The pH-dependent colloidal stability of aqueous montmorillonite suspensions

Colloidal stability of bentonite clay considering surface charge properties as a function of pH and ionic strength

“…The titration curves for the bentonite colloids shown in Fig. 3 reflect a typical titration shape of montmorillonite clay with a high permanent layer charge and a negligible variable charge [14,26,27]. This similar behavior of the bentonite colloids to the montmorillonite clay may be due to the fact that the bentonite colloids prepared from the natural Gyeongju bentonite only consisted of montmorillonite as mentioned previously.…”

“…In general, the permanent charge sites in the montmorillonite clay are considered to be strong acidic sites and the contribution of the amphoteric edge sites to the total charge of the clay is not significant [27]. Thus it is considered that the pH-dependent variable charge at the edges only represents a small fraction of the total charge of the bentonite colloids.…”

Acid–base properties of bentonite rocks with different origins

“…This model was initially developed for oxide surfaces [2,3], but later it was applied for the study of the acid-base properties of different minerals and to the evaluation of ion sorption [4][5][6][7][8][9][10][11]. The application of surface complexation modeling to calciummontmorillonite has been discussed in Refs.…”

Adsorption and flocculation of bentonite by chitosan with varying degree of deacetylation and molecular weight

“…With increasing pH, the surface hydroxyl groups successively undergo deprotonation, decreasing the positive charge and eventually reversing the positive charge to negative on the edge. However, in general, the contribution of the amphoteric edge sites to the total charge of the bentonite is estimated to be between 1 and 10% [30][31][32]. Thus it is considered that the pH-dependent variable charge at the edges only represents a small fraction of the total charge of the bentonite colloids.…”