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Hard and Soft Acid-Base Model Applied to Bivalent Cation Selectivity on a 2:1 Clay Mineral
Bivalent Cations Covalent Bonding Electronegativity HSAB Montmorillonite Selectivity Coefficient Softness
2011/12/8
Abstract: We applied the hard and soft acid-base (HSAB) model (Xu and Harsh 1990a, 1990b) to bivalent cation exchange on a purified Ca-montmorillonite. As a result, a satisfactory model is proposed to...
Relationship Between Cation Exchange Selectivity and Crystalline Swelling in Expanding 2:1 Phyllosilicates
Cation Exchange Selectivity Crystalline Swelling Demixing Fixation Ion Exchange Hysteresis Layer Charge Smectite
2011/12/22
Abstract: A theoretical model describing the interaction between crystalline swelling and cation exchange selectivity is proposed for expanding 2:1 phyllosilicates. The model is based on the assumptio...
Alkali Cation Selectivity and Surface Charge of 2:1 Clay Minerals
Hard/soft acid/base model Ion exchange Isomorphic substitution Layer charge Lewis acid Lewis base Smectite Surface complexation Vermiculite
2011/12/31
A critical demand in environmental modeling and a desirable but elusive goal of research on the ion exchange properties of the charged solid surface has been to determine the selectivity coefficient f...
ALKALI CATION SELECTIVITY AND SURFACE CHARGE OF 2:1 CLAY MINERALS
Hard/soft acid/base model Ion exchange Isomorphic substitution Layer charge Lewis acid
2011/11/15
A critical demand in environmental modeling and a desirable but elusive goal of research on the ion exchange properties of the charged solid surface has been to determine the selectivity coefficient f...
Interpretation of the Variability of Selectivity Coefficients for Exchange Between Ions of Unequal Charge on Smectites
Cation exchange Cation selectivity Entropy Mass action Selectivity coefficient Smectite
2012/2/9
Ion-exchange experiments in expanding clay minerals conducted over a wide range of surface ionic compositions and ionic strength produce variable mass-action selectivity coefficients. When the exchang...
Alkali Cation Selectivity and Fixation by Clay Minerals
Cation exchange Cation fixation Cation selectivity Equivalent anionic radius Free energy of exchange Illite Smectite
2012/2/9
Two variables must be considered when calculating exchange free energies (ΔG0ex) for 2:1 clays: (1) anionic field strength, as expressed by equivalent anionic radius (ra), and (2) interlayer water con...
An Interpretation of Cation Selectivity Variations in M+—M+ Exchange on Clays
Adsorption Cation exchange Montmorillonite Selectivity Statistical mechanics
2012/2/10
The decreasing preference of montmorillonite for K+ relative to Na+ as the clay adsorbs increasing amounts of K+ is shown to be the general rule for the exchange of strongly hydrating ions by weakly h...
Selectivity and Adsorption Capacity of Smectite and Vermiculite for Aluminum of Varying Basicity
Adsorption Aluminum Expansion Smectite Vermiculite
2011/11/18
Smectite (from South Dakota, Wyoming, and Mississippi) and vermiculite (Transvaal) were treated with solutions of Al(OH)B(3−B)+, with B varying from 0 to 2.5. The average basicity (OH/Al = B) of...
Experimental Evaluation of Ca-K Exchange Selectivity Reactions in Estuarine Sediments
Experimental Evaluation Ca-K Exchange Selectivity Reactions Estuarine Sediments
2011/11/18
Abstract: Clay materials separated from estuarine sediments in Louisiana exhibit a selectivity for exchangeable calcium in laboratory experiments. The studies were conducted at 25°C and 60°C in mixed ...
Potassium Selectivity of Clays as Affected by the State of Oxidation of Their Crystal Structure Iron
Potassium Selectivity of Clays Crystal Structure Iron Oxidation
2011/11/18
Abstract: The Ca-K exchange isotherms were determined at two temperatures for two highly montmorillonitic iron-rich soil clays in their oxidized and reduced states. The thermodynamic parameters K, ΔG0...
Selectivity Effect of Cesium on Clay Size Weathered Mica; Transmission Electron Microscopy Studies
Selectivity Effect Cesium Clay Size Mica Transmission Electron Microscopy Studies
2012/2/17
The use of electron diffraction contrast to detect local concentrations of interlayer cations in mica-vermiculites was examined. Cs and Mg, because of their contrasting atomic scattering amplitudes fo...
Adsorption of Hydroxy-Al by Certain Phyllosilicates and its Relation to K/Ca Cation Exchange Selectivity
Adsorption Hydroxy-Al Certain Phyllosilicates K/Ca
2012/2/20
The adsorption of hydroxy-Al by the 2?? ?size fractions of muscovite, biotite, K-depleted micas, vermiculite and montmorillonite was studied. The differences in the amounts of hydroxy-Al adsorbed were...
Potassium and Cesium Ion Selectivity in Relation to Clay Mineral Structure
Potassium Cesium Ion Selectivity Clay Mineral Structure
2011/11/17
Abstract: Selectivity of a number of vermiculites, montmorillonites and micas for K and Cs ions was determined by sorption of these ions from equilibrium solutions of diverse concentrations. The selec...