7Li Double Quantum Filtered NMR and Multinuclear Relaxation Rates of Clay Suspensions: The Effect of Clay Concentration and Nonionic Surfactants

Grandjean, Jean; Robert, Jean-Louis

doi:10.1006/jmre.1999.1722

Cited by 8 publications

(6 citation statements)

References 20 publications

(50 reference statements)

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“…The occurrence of hydration number smaller than six is the fingerprint of the formation of ion-surface contact ionic pairs. Such formation of contact ion-pair, recently detected by atomic force microscopy, 75 may be responsible for the anomalous behavior reported by 23 Na NMR spectroscopy 76 in the presence of clay lamellae with a high fraction of surface charged sites. It also induces a reduction of the net electric charge of the platelets, responsible for its long-distance repulsion and thus its mechanical behavior.…”

Section: Resultsmentioning

confidence: 87%

Beyond the Diffuse Layer Theory: A Molecular Analysis of the Structural, Dynamical, and Mechanical Properties of Charged Solid/Liquid Interfaces

Delville

2013

J. Phys. Chem. C

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This work focuses on the long-range gap detected during the swelling of charged solid/liquid interfaces neutralized by monovalent counterions. A molecular model is used to investigate the influence of the long-range electrostatic coupling on the thermodynamical properties of charged solid/ liquid interfaces at separations varying between 20 and 40 Å, corresponding to the transition between discontinuous crystalline swelling, detected below 20 Å, and the continuous osmotic swelling, detected at separations larger than 40 Å. While the primitive model perfectly reproduces the stability of these charged interfaces in the osmotic swelling regime, it becomes inappropriate in the crystalline swelling regime, since it neglects the organization of the confined water molecules which is responsible for the discontinuous crystalline swelling. In that context, we study the influence of the valence of the neutralizing counterions and the location of the electric charges embedded within the charged lamellae on the structural, dynamical, and mechanical properties of these interfacial systems. This molecular approach clearly identifies two different environments accessible to the neutralizing sodium counterions, corresponding respectively to solvent separated and contact ionic pairing. The mobility of the confined counterions and water molecules is quantified by numerical simulations of molecular dynamics. Finally, the interfacial free energy provides, without introducing any additional parameter, the first theoretical interpretation of the coexistence between swollen and collapsed charged interfaces neutralized by monovalent counterions, in agreement with experimental evidence.

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Section: Resultsmentioning

confidence: 87%

Beyond the Diffuse Layer Theory: A Molecular Analysis of the Structural, Dynamical, and Mechanical Properties of Charged Solid/Liquid Interfaces

Delville

2013

J. Phys. Chem. C

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“…No splitting of these two broad resonance lines (see Figure ) may indeed be detected if it is lower than the intrinsic broadening of the lines. Under such conditions, a large increase of the sensitivity will result from the detection by using double-quantum filtering in order to select only these two broad components with an opposite phase. − …”

Section: Resultsmentioning

confidence: 99%

²³Na Nuclear Magnetic Resonance and ¹H Pulsed Gradient Spin−Echo Detection of the Critical Concentration Corresponding to the Isotrope/Nematic Transition within Aqueous Dispersions of Charged Anisotropic Nanoparticles

et al. 2004

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With the use of 23 Na nuclear magnetic resonance spectroscopy and 1 H pulsed field gradient attenuation, we have determined the critical concentration at which the isotrope/nematic transition occurs within aqueous dispersions of synthetic Laponite clay used as a model of a charged anisotropic colloid. The dense macroscopic clay samples were prepared by oedometric compression, leading to a critical concentration for the isotrope/ nematic transition significantly higher than that determined previously by using birefringence detection within capillary tubes. The increase of the nematic ordering detected by NMR as a function of the clay concentration is more progressive than the sharp ordering predicted by numerical simulations of the isotrope/nematic transition of rigid disks. This difference may result from some size and shape heterogeneities of the Laponite clay samples or from the competition between the relative orientation of the particles induced by the excluded volume and the electrostatic interactions.

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“…The chemical formula of these saponites is Na 1 -x Mg 3 (Si 3+x Al 1 -x )O 10 (OH) 2 .nH 2 O per half unit cell. Laponite RD (Laporte organics, UK) a synthetic hectorite with a layer charge of 0.28 per half unit cell (Grandjean & Robert, 1999) was used as received. The negative charge of the investigated minerals is compensated with Na + counterions.…”

Section: A T E R I a L S A N D M E T H O D Smentioning

confidence: 99%

“…The opposite behaviour is observed with the other Li-exchanged clay. Fast exchange between two mean interfacial sites may explain such behavi our wi t h t he hi ghest -charged cl ay (Grandjean & Robert, 1999).…”

Section: Counterion Nucleimentioning

confidence: 99%

“…As part of our investigations on synthetic clay suspensions, we have studied the properties of Na + and Li + cations that counterbalance the negative charges of clay platelets. The strength of the cation interaction with the solid surface affects its environment, and modulates the interaction of nonionic (Grandjean & Robert, 1999;Gevers & Grandjean, 2001), and zwitterionic (Grandjean, 2001) surfactants with clays. Surfactant interaction is found with Laponite and low-charge saponites in suspension.…”

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confidence: 99%

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²³Na 2D 3QMAS NMR and ²⁹Si, ²⁷Al MAS NMR investigation of Laponite and synthetic saponites of variable interlayer charge

2003

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Abstract29Si, 27Al MAS NMR is used to characterize Laponite RD and synthetic saponites of variable interlayer charge. The Si/Al ratios are in good agreement with the calculated charge from chemical analysis except for the lowest-charged saponite. In contrast to the 29Si MAS NMR spectra in which resolved signals are detected, the 27Al MAS NMR spectra show one signal whose linewidth increases with the clay charge. The water content of the clay samples was obtained from 1H MAS NMR.The 2D MQMAS NMR technique is required to obtain a high-resolution spectrum of nuclei with strong quadrupolar interaction. This method was applied to the 23Na nucleus of clay counterions and to the 27Al structural nucleus. One well-defined 23Na NMR signal is observed for all the clays studied except the highest-charged saponite. Possible explanations for this different behaviour are discussed. The calculated isotropic chemical shift evolves progressively with the clay charge whereas the deduced quadrupolar interaction does not change significantly. The 27Al 2D 3QMAS technique was not able to resolve more than one signal.

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7Li Double Quantum Filtered NMR and Multinuclear Relaxation Rates of Clay Suspensions: The Effect of Clay Concentration and Nonionic Surfactants

Cited by 8 publications

References 20 publications

Beyond the Diffuse Layer Theory: A Molecular Analysis of the Structural, Dynamical, and Mechanical Properties of Charged Solid/Liquid Interfaces

Beyond the Diffuse Layer Theory: A Molecular Analysis of the Structural, Dynamical, and Mechanical Properties of Charged Solid/Liquid Interfaces

²³Na Nuclear Magnetic Resonance and ¹H Pulsed Gradient Spin−Echo Detection of the Critical Concentration Corresponding to the Isotrope/Nematic Transition within Aqueous Dispersions of Charged Anisotropic Nanoparticles

²³Na 2D 3QMAS NMR and ²⁹Si, ²⁷Al MAS NMR investigation of Laponite and synthetic saponites of variable interlayer charge

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7Li Double Quantum Filtered NMR and Multinuclear Relaxation Rates of Clay Suspensions: The Effect of Clay Concentration and Nonionic Surfactants

Cited by 8 publications

References 20 publications

Beyond the Diffuse Layer Theory: A Molecular Analysis of the Structural, Dynamical, and Mechanical Properties of Charged Solid/Liquid Interfaces

Beyond the Diffuse Layer Theory: A Molecular Analysis of the Structural, Dynamical, and Mechanical Properties of Charged Solid/Liquid Interfaces

23Na Nuclear Magnetic Resonance and 1H Pulsed Gradient Spin−Echo Detection of the Critical Concentration Corresponding to the Isotrope/Nematic Transition within Aqueous Dispersions of Charged Anisotropic Nanoparticles

23Na 2D 3QMAS NMR and 29Si, 27Al MAS NMR investigation of Laponite and synthetic saponites of variable interlayer charge

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²³Na Nuclear Magnetic Resonance and ¹H Pulsed Gradient Spin−Echo Detection of the Critical Concentration Corresponding to the Isotrope/Nematic Transition within Aqueous Dispersions of Charged Anisotropic Nanoparticles

²³Na 2D 3QMAS NMR and ²⁹Si, ²⁷Al MAS NMR investigation of Laponite and synthetic saponites of variable interlayer charge