Surface Potentials Derived from Co-Ion Exclusion Measurements on Homoionic Montmorillonite and Illite

Chan, Derek Y. C.

doi:10.1346/ccmn.1984.0320207

Cited by 43 publications

(8 citation statements)

References 23 publications

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“…The smaller value corresponds to low surface potentials (--<50 mV) and the large value to surface potentials >-150 inV. As the surface potentials calculated from the surface charge density are distinctly higher, the observed CK ratio confirms the strong Stern-layer adsorption of the inorganic counterions (Chan et al, 1984;Goldberg, 1992; Gan and Low, 1993;Lagaly, 1994a, 1994b;Quirk and Mar~elja, 1997). The monovalent organic cations are adsorbed more strongly than the inorganic ions.…”

Section: Critical Coagulation Concentrationmentioning

confidence: 77%

Influence of Organic and Inorganic Salts on the Coagulation of Montmorillonite Dispersions

Penner

Lagaly

2000

Clays and clay miner.

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Abstracts-The colloidal state (stable, coagulated, or gel-like) and the theological properties of Na-rich montmorillonite (Wyoming) dispersions are strongly influenced by organic cations. This effect is shown for homologous organic cations: alkyl trimethylammonium ions, paraquat, diquat, alkyl bispyridinium ions, and the triphenylmethane dyes crystal violet, methyl green, and tris (tri-methylammonium phenyl) methane chloride. The critical coagulation concentrations, cK, are small (often < 1 mmol/L) because the cations are enriched in the Stern layer and influence the solvent structure near the surface. The strong adsorption of the counterions at the clay-mineral surface causes CK values to increase with the solid content. Charge reversal (recharging) of the particles was observed with the longer chain alkyl trimethylammonium ions, dodecyl bispyridinium ions, and crystal violet. Other cations reduced the electrophoretic mobility to zero but positive particle charges were not observed.The plastic viscosity increased sharply at the critical coagulation concentration and showed a minimum slightly below cK, which was caused by the electroviscous effect. Yield values were developed at concentrations above CK. In most cases, yield values reached a plateau where the amount of organic cations was -0.5 mmol/g, i.e., about half of the cation-exchange capacity. The cK values decreased with increasing hydrophobicity of homologous compounds, but the yield value showed maxima at intermediate chain lengths. The yield value of several 0.5% dispersions was high, e.g., dodecyl trimethylammonium ions, 71 Pa; paraquat, 100 Pa; diquat, 42 Pa; hexyl bispyridinium ions, 53 Pa (vs. Ca 2 § 0.2 Pa; AP +, 0.7 Pa). The storage modulus as a function of the number of organic cations changed in a similar way as the yield value, and high values were observed (e.g., dodecyl trimethylammonium ions, hexyl bispyridinium ions: 1000 Pa, paraquat: >4000 Pa). Thus, dispersions with high viscosity, yield value, and pronounced viscoelasticity are obtained by coagulating Na-rich montmorillonite dispersions with organic cations.

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Section: Critical Coagulation Concentrationmentioning

confidence: 77%

Influence of Organic and Inorganic Salts on the Coagulation of Montmorillonite Dispersions

Penner

Lagaly

2000

Clays and clay miner.

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“…Accordingly, it has been assumed that the surface charge density is constant and equals the quotient of the cation-exchange capacity and surface area. From the results of Low (1981) and Chan et aL (1984), however, and from unpublished results obtained recently in this laboratory, it appears that: (1) most of the exchangeable cations are adsorbed on the silicate surface in a Stem layer, (2) the values of~, the charge density at the inner boundary of the diffuse layer, and of fr, the potential at this boundary, are much smaller than the corresponding values at the silicate surface, (3) f~ is constant but ~, is variable, and (4) the electrophoretically measured ~" potential provides a good estimate of ~br. The g" potential of Li-vermiculite in 10 -4 N LiC1 is between 50 and 90 mV (Friend and Hunter, 1970).…”

Section: Methodsmentioning

confidence: 99%

Direct Measurement of the Relation Between Swelling Pressure and Interlayer Distance in Li-Vermiculite

Viani

Roth

Low

1985

Clays and clay miner.

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Abstract--To test the double-layer theory of swelling as applied to layer silicates, the interlayer separation, X, in a Li-saturated vermiculite from Grouse Creek, Utah, was measured as a function of the swelling pressure, II. An oriented sample of the vermiculite (46-105 izm) was placed in an environmental chamber mounted on an X-ray diffractometer and compressed between N2 gas and a porous membrane in contact with a solution draining to the outside atmosphere. After equilibration at each of several successively higher gas pressures, the c-axis spacing was measured by X-ray diffraction, and the corresponding k was calculated by subtracting the thickness of an elementary silicate layer. The results of these measurements showed that: (1) the relation between II and ~ for vermiculite is the same as that previously observed for Na-montmorillonite, i.e., 131 is an exponential function of 1/),; (2) the values of II predicted by doublelayer theory are much smaller than those observed if the surface potential is assigned the appropriate value; and (3) the observed relation between II and ~, does not have the form predicted by this theory. On the basis of these results, a repulsive force not ascribable to double-layer overlap must be primarily responsible for swelling; this force must result from the in-depth perturbation of the water by the surfaces of the vermiculite layers.

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“…The more strongly hydrated monovalent cations (Li + and Na + ) were seen to bind more weakly to the negatively charged clay surface, giving rise to higher zeta potentials (in absolute values, the potentials remaining negative), while the less strongly hydrated cations (NH + 4 , Rb + , Cs + ) were seen to bind more strongly to the surface, giving rise to relatively low potentials (24,25).…”

Section: Comparison With Other Studiesmentioning

confidence: 99%

Zeta-Potential Study of Calcium Silicate Hydrates Interacting with Alkaline Cations

Viallis-Terrisse

Nonat

Petit

2001

Journal of Colloid and Interface Science

221

130

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Surface Potentials Derived from Co-Ion Exclusion Measurements on Homoionic Montmorillonite and Illite

Cited by 43 publications

References 23 publications

Influence of Organic and Inorganic Salts on the Coagulation of Montmorillonite Dispersions

Influence of Organic and Inorganic Salts on the Coagulation of Montmorillonite Dispersions

Direct Measurement of the Relation Between Swelling Pressure and Interlayer Distance in Li-Vermiculite

Zeta-Potential Study of Calcium Silicate Hydrates Interacting with Alkaline Cations

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