Layer charge and electrophoretic mobility of smectites

Surface chemistry of kaolinite and Na-montmorillonite in aqueous electrolyte solutions at 25 and 60°C: Experimental and modeling study

“…The particular behavior of clays, compared with simple oxides, is linked to the negative permanent charge of these minerals, which is higher for montmorillonite than for kaolinite. Furthermore, electrokinetic measurements on clays (Hussain et al, 1996;Sondi et al, 1997;Avena and De Pauli, 1998;Thomas et al, 1999;Missana and Adell, 2000;Hu and Liu, 2003) show systematically negative potential values whatever the pH and the ionic strength investigated, even for kaolinite which has the lowest CEC. Nevertheless, only few authors (Avena and De Pauli, 1998;Kraepiel et al, 1998; have used these observations at 25°C to develop models for the clay/solution interface.…”

Adsorption and in vitro release of vitamin B1 by synthetic nanoclays with montmorillonite structure

“…The average particle size was determined according to the Scherrer equation by the reflection band of 2θ = 19°(d 110 ) that characterises the particles size in the plane perpendicular to the c axis. CEC was measured by the ion-exchange reaction with hexammine cobalt (III) ions [Co(NH 3 ) 6 ] 3+ (Thomas et al, 1999). First, 500 mg of Mt samples was dispersed in 30 ml of a 0.05 M hexammine cobalt (III) chloride solution.…”

Advanced Nano-biocomposites Based on Starch

“…The charge amount is characterized by the cationic exchange capacity (CEC) and corresponds to the amount of monovalent cations necessary to compensate the platelet negative charge, which is usually given in milliequivalent per 100 g (meq/100 g). For instance, the CEC of MMT varies from 70 to 120 meq/100 g depending on their extraction site (Thomas et al 1999).…”