Heterogeneity of cation-exchange sites for KCa exchange in aluminosilicates

Goulding, Keith; Talibudeen, O.

doi:10.1016/0021-9797(80)90490-7

Cited by 60 publications

(53 citation statements)

References 14 publications

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“…The AS0 values show that replacing Ca by K on exchange sites introduces the highest degree of order in samples D and F which have appreciable amounts of hydrous micas, with vermiculite and with montmorillonite, respectively. Sample B has smaller amounts of these minerals, hence a less negative AS0 value, than samples D and F. Notably, sample E exhibits a positive entropy change of 3.3 J/K/ eq, a property observed for pure muscovite mica (Goulding and Talibudeen, 1980). Samples A, B, and C, of low 2:1 layer mineral content, give similar values for these standard functions.…”

Section: Integral Thermodynamic Functionsmentioning

confidence: 78%

“…The clays were calcium saturated before the heats of the K-Ca exchange reaction and the exchange isotherms were determined (Goulding and Talibudeen, 1980). The methods for determining changes in the differential heat of exchange, -d(AHx)/dx, with fractional K saturation, x, and for relating sites with constant differential heats to specific 2: I phyllosilicates were described by Goulding and Talibudeen (1980) and Talibudeen and Goulding (1983).…”

Section: Methodsmentioning

confidence: 99%

“…The methods for determining changes in the differential heat of exchange, -d(AHx)/dx, with fractional K saturation, x, and for relating sites with constant differential heats to specific 2: I phyllosilicates were described by Goulding and Talibudeen (1980) and Talibudeen and Goulding (1983).…”

Section: Methodsmentioning

confidence: 99%

“…In the present study, heat measurements of K-Ca exchange, as described by Goulding and Talibudeen (1980) have been performed on six kaolins for the quantitative determination of such impurities.…”

Section: Introductionmentioning

confidence: 99%

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Apparent Charge Heterogeneity in Kaolins in Relation to Their 2:1 Phyllosilicate Content

Talibudeen

Goulding

1983

Clays and clay miner.

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Abstract----Measurements of the differential heats of K-Ca exchange are used to show that 6 groups of sites (ranging from -13.8 to -5.1 kJ/eq and with as many as 4 in any one sample) exist in kaolins that range from 0 to 15% in their 2:1 phyllosillicate content. These heat values, coupled with entropies of exchange, suggest that 0.1-10% vermiculitic, micaceous, and smectitic layers are present, presumably interstratified with kaolinitic layers which are assumed to have no permanent charge. Changes in the activity coefficients of adsorbed K with K saturation confirm these conclusions qualitatively. Thus, fK values at x ~ 0 correlate inversely (r 2 = 0.655) with the content of vermiculite + partially expanding micas, and x values at maximumfKindicatethecontentofvermiculite + nonexpandingmica + partially expanding micas (r 2 = 0.732).

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Section: Integral Thermodynamic Functionsmentioning

confidence: 78%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Apparent Charge Heterogeneity in Kaolins in Relation to Their 2:1 Phyllosilicate Content

Talibudeen

Goulding

1983

Clays and clay miner.

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“…The contribution of the entropies of ions in solution to the observed entropy change for limiting values of ion concentration was evaluated by Goulding and Talibudeen (1980) as follows. Entropies of ions in solution, S~, at 0.1 N can be calculated by the relationship…”

Section: Loa/t(k -' )mentioning

confidence: 99%

Thermodynamic Study of Na-K-Ca Exchange Reactions in Vermiculite

Inoue

1984

Clays and clay miner.

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Abstract--The exchange of Na, K, and Ca ions in vermiculite has been studied between 50 and 1500C at a total normality of 0.1. The free energy changes were negative in the Na ~ K, Ca ~ K, and Na ~ Ca exchange reactions, and the cation preference in the vermiculite was Na < Ca < K in the temperature range examined. The enthalpy changes, calculated by application of the van't Hoffequation to the relation between equilibrium constant and temperature, were positive. The cation preference in the vermiculite seems to have been largely controlled by the increase in entropy which was due to the positive values of the entropy change term in the solid for the Na-K and Ca-K exchanges and the positive values of the entropy change in the solution for the Na-Ca exchange. From a thermodynamic analysis of the cationmixing properties in vermiculite, the observed free energy change in the Na-K exchange was determined solely by the differences of the intrinsic electrostatic binding energy of the cations on the clay surface. That in the Na-Ca exchange was interpreted by taking into account an extra interaction energy of Ca-Ca pairs in addition to the intrinsic energy change. Furthermore, an additional interaction energy between K ions and the clay surface appears to have been added to the free energy change in the Ca-K exchange. In the Na ~ K and Ca ~ K exchange reactions a structural modification occurred in the K-equivalent fraction (RI0 range 0.05--0.6, and a regularly interstratified phase of 15-A and 10-A members was formed at 0.05 < Y(K < 0.4.

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Exchange Selectivity, Cation Exchange Isotherm

2006

Handbook of Soil Analysis

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Heterogeneity of cation-exchange sites for KCa exchange in aluminosilicates

Cited by 60 publications

References 14 publications

Apparent Charge Heterogeneity in Kaolins in Relation to Their 2:1 Phyllosilicate Content

Apparent Charge Heterogeneity in Kaolins in Relation to Their 2:1 Phyllosilicate Content

Thermodynamic Study of Na-K-Ca Exchange Reactions in Vermiculite

Exchange Selectivity, Cation Exchange Isotherm

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