Under appropriate conditions, both surface areas and cation exchange capacities of clay minerals can be measured by absorption of methylene blue from aqueous solutions. The method has been applied to two kaolinites, one illite, and one montmorillonite, all initially saturated with Na + ions. For Na-montmorillonite, the total area, internal plus external, is measured. For Ca-montmorillonite, ent...

a mild, efficient and fast method for the oxidation of alcohols and trimethylsilyl and tetrahydropyranyl ethers to their corresponding carbonyl compounds using cro3 in the presence of sulfonic acid functionalized ordered nanoporous na+-montmorillonite (sanm) and under solvent-free conditions is reported. all reactions were performed at room temperature in high to excellent yields. ease of the p...

The dissolution and swelling properties of montmorillonite at different pH have been studied, using small angle X-ray scattering (SAXS), imaging and osmotic stress methods combined with Monte Carlo simulations. The acidity of montmorillonite dispersions has been varied as well as the counterions to the net negatively charged platelets. At low pH, Na montmorillonite dissolves and among other spe...

1 We studied the interaction between the naturally occurring polycation spermine (SPERM) and 2 Na-exchanged SWy-2 Wyoming montmorillonite (Na-SWy-2 Mt) and between spermine3 exchanged montmorillonite (Mt-SPERM) and the herbicide fluometuron. Mt-SPERM with 4 spermine contents ranging between 0 and 1.2 times the cation exchange capacity (CEC) of 5 Na-SWy-2 were studied by XRD, FTIR and TGA analys...

Bentonites are widely used for waste repository systems because of their hydrodynamic, surface and chemical-retention properties. MX 80 bentonite (bentonite of Wyoming) contains approximately 85% Na/Ca-montmorillonite and 15% accessory minerals. The dominant presence of Na/Ca-montmorillonite in this clay mineral could cause it to perform exceptionally well as an engineered barrier for a radioac...

-The effect of ethylene oxide-sterilization on homoionic (Na +, K § Ca 2+, Cu 2+, A1 s+, and Fe 3+) montmorillonite samples was examined. The results indicate that ethylene oxide polymerized to polyethylene glycol in the interlayer of Cu 2+-, AP +-, and FeS+-saturated clays, as substantiated by the increase in the d(001) values, as well as by the decrease in the cation-exchange capacity after r...

The effect of temperature in the range of 0–150 8C was studied for homoionic montmorillonite clays with Na and Csqq compensating ions in low hydration states. Both static and dynamic information concerning the interlayer ions and water moleculeswas obtained by Monte Carlo and molecular dynamics. Principal structural changes were limited to the water phase, markeddifference was o...

Surfaces of Wyoming SWy-2-Na-montmorillonite were modified using ultrasonic and hydrothermal methods through the intercalation and adsorption of the cationic surfactant octadecyltrimethylammonium bromide (ODTMA). Changes in the surfaces and structure were characterized using X-ray diffraction (XRD), thermal analysis (TG), and electron microscopy. The ultrasonic preparation method results in a h...

-The conditions under which an exchanger phase will behave as an ideal mixture are established from thermodynamic principles. It is shown that, if a stoichiometric cation-exchange reaction is reversible, the exchanger phase will exhibit ideal behavior if the Vanselow selectivity coefficient is independent of the exchanger composition. This criterion is applied to some recently published data fo...