Stoichiometry of smectite dissolution reaction

Effect of pH and organic ligands on the kinetics of smectite dissolution at 25°C

“…The activity coefficients of free ions and charged complexes were calculated using the Davies equation which is standard in MINTEQA2. In the absence of a specific K eq value for smectite sample SWy-2, the solubility constant of the MINTEQA2 thermodynamic database for Mg-endmember smectite (Mg 0.48 Fe 0.22 Al 1.71 Si 3.81 O 10 (OH) 2 , log K = À2.67) was used in the calculation, consistent with those of SWy-1 used by Amram and Ganor (2005) and Metz et al (2005a). Besides, additional calculations of saturation degree were performed with respect to (1) Na-montmorillonite Na 0.35 Mg 0.35 Al 1.65 Si 4 O 10 (OH) 2 (Wilson et al, 2006), and (2) three different smectites (Ca, H, Na, K, and Namontmorillonites) of the PHREEQC and EQ3NR (Wolery, 1983) database.…”

Dissolution kinetics of soil clays in sulfuric acid solutions: Ionic strength and temperature effects

“…In several other studies on clay dissolution, it has been reported that quartz remains relatively unaffected even in extremely acidic solutions (pH À3.5), and the Si released during these experiments was mainly from the dissolution of phyllosilicates (Belver et al, 2002;Komadel, 2003;Madejova et al, 1998). By contrast, Metz et al (2005a) investigated the dissolution of smectite and suggested that the initial higher concentration of Si compared to Al was due to the fast dissolution of amorphous silica particles, which were present as an impurity in the mineral sample. Rozalen et al (2009b) also observed high initial Si and low Al concentrations from acidic dissolution of montmorillonite and attributed this to the presence of impurities.…”

Dissolution rates of silicate minerals in water from a subcritical to a supercritical state: effect of solvent properties

“…The experimental apparatus consisted of a titanium vessel, a liquid pump, a backpressure regulator, an electrical conductivity detector, and a computer for data acquisition and monitoring. A packed-bed reactor has previously been used to perform kinetic experiments (called column experiments [11][12][13][14][15][16][17][18]). …”