Identification of montmorillonite particle edge orientations by atomic-force microscopy

Kraevsky, Sergey V.; Tournassat, Christophe; Vayer, Marylène; Warmont, Fabienne; Grangeon, Sylvain; Wakou, Brice Firmin Ngouana

doi:10.1016/j.clay.2020.105442

Cited by 21 publications

(22 citation statements)

References 59 publications

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“…All other parameters were obtained from direct measurements or independent models such as first principle molecular dynamics (FPMD). ,, In the proposed electrostatic model, an important assumption is the crystalline nature of clay edge surfaces for which a structure identical to the bulk layer structure was considered to calculate protonation–deprotonation reaction constant using FPMD techniques. ,− , Our HR-STEM results provide a strong case of the adequacy of the crystallinity assumption. Besides, recent atomic force microscopy measurements enabled to quantify the preferential orientation of Kunipia montmorillonite edge surfaces, and results were in good agreement with the average orientation considered in our model. While these findings support the adequacy of the proposed model, the number of possible site combinations for Pb 2+ , Mg 2+ , and Zn 2+ adsorption makes it impossible to warrant unicity of the model parameters, and different combinations of adsorption and log K values may be as effective as the set of parameters fitted in this study.…”

Section: Modeling and Discussionsupporting

confidence: 82%

“…The crystallographic orientation of the edge surfaces and the existence of various functional groups on these surfaces are fundamental assumptions of the model. Theoretical calculations predicted that the most abundant edges surfaces are perpendicular to [010] and [110] crystallographic directions. − This preferred orientation was evidenced recently by direct observations using AFM techniques . The crystalline nature of clay mineral edge surfaces is another prerequisite to the applicability of the model that builds on an edge surface structure that is identical to the structure of the inner layer.…”

Section: Theoretical Backgroundmentioning

confidence: 95%

“…57−59 This preferred orientation was evidenced recently by direct observations using AFM techniques. 60 The crystalline nature of clay mineral edge surfaces is another prerequisite to the applicability of the model that builds on an edge surface structure that is identical to the structure of the inner layer. This crystalline nature of edge surfaces can be tested directly by imaging clay mineral layer with atom−resolution techniques.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Competitive Adsorption Processes at Clay Mineral Surfaces: A Coupled Experimental and Modeling Approach

Oruçoğlu

Grangeon

Gloter

et al. 2022

ACS Earth Space Chem.

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Quantification of adsorption processes on clay mineral surfaces is often necessary to predict the extent and the evolution of contaminants’ migration in surficial and underground environments. Many studies have been dedicated to retention measurement as a function of pH and ionic strength in relation with the two main identified adsorption processes for clay minerals, that is, cation exchange on their basal surfaces and surface complexation on their edge surfaces. The latest process has been repeatedly assessed as an effective retention mechanism at circumneutral pH conditions, which often prevail in natural environments. This assessment must however be tempered by the lack of information about competitive processes that can take place with the numerous chemical species present in natural settings, compared to simplified systems investigated in laboratory experiments. In this study, we quantified experimentally the competition between Pb2+, Co2+, Zn2+, and Mg2+ for specific adsorption on montmorillonite edge surfaces. Zn2+ was an effective competitor with Pb2+ and Co2+, and our results showed also unambiguously the influence of Mg2+ concentration levels on the specific adsorption of Pb2+ and Co2+. Because of the high ionic strength used in the experiments, cation exchange with Mg2+ was dismissed as a possible reason for such competition process, leaving specific competitive adsorption on edge surfaces as a unique explanation for our observations. Modeling of Pb2+ adsorption data with a state-of-art electrostatic complexation model for montmorillonite edge surfaces, supported by state-of-the-art, made it possible to distinguish two types of possible competition driving forces: Zn2+ competition for adsorption site occupancy but also detrimental changes in surface electrostatic potential following Mg2+ adsorption on sites neighboring those of Pb2+ adsorption. Mg2+ competition observed in our experiment should apply in most of clayey environments. Consequently, adsorption data obtained on pure clay mineral phases, and the associated models that have been built based on these data without considering the geochemical background in competitive species, may overestimate the retention properties of clay minerals when applied to natural settings.

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Section: Modeling and Discussionsupporting

confidence: 82%

Section: Theoretical Backgroundmentioning

confidence: 95%

Section: Theoretical Backgroundmentioning

confidence: 99%

See 1 more Smart Citation

Competitive Adsorption Processes at Clay Mineral Surfaces: A Coupled Experimental and Modeling Approach

Oruçoğlu

Grangeon

Gloter

et al. 2022

ACS Earth Space Chem.

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“…Several recent studies have demonstrated a very good agreement of the 2-D and 3-D interfacial aqueous solution structures at heterogeneously charged basal and edge surfaces of clay nanoparticles simulated with Clayff with results from experimental atomic force microscopy (AFM) observations. − These studies illustrate the value of using molecular simulations as a tool in the atomistic-scale interpretation of complex AFM results.…”

Section: Advances In Clayffmentioning

confidence: 80%

Advances in Clayff Molecular Simulation of Layered and Nanoporous Materials and Their Aqueous Interfaces

2021

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As a general-purpose force field for molecular simulations of layered materials and their fluid interfaces, Clayff continues to see broad usage in atomistic computational modeling for numerous geoscience and materials science applications due to its (1) success in predicting properties of bulk nanoporous materials and their interfaces, (2) transferability to a range of layered and nanoporous materials, and (3) simple functional form which facilitates incorporation into a variety of simulation codes. Here, we review applications of Clayff to model bulk phases and interfaces not included in the original parameter set and recent modifications for modeling surface terminations such as hydroxylated nanoparticle edges. We conclude with a discussion of expectations for future developments.

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“…Two main approaches have been developed to characterize clay particles’ aspect ratio : direct electron and close field microscopy image analysis − and indirect methods relying on the detection of molecular probe interaction with the surface domains. The latter group of methods mainly includes measurements of high-resolution Ar or N 2 adsorption isotherms at 77 K (derivative isotherm summationDIS) , and adsorption microcalorimetry analysis. , They allow monitoring of the adsorbed amount variation with pressure and thermal effects of adsorption, respectively, upon progressive coverage of the structurally and energetically heterogeneous clay surface with probe molecules.…”

Section: Introductionmentioning

confidence: 99%

Direct Experimental Evidence of the Effects of Clay Particles’ Basal-to-Lateral Surface Ratio on Methane and Carbon Dioxide Adsorption

et al. 2021

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The amount and size of the charge-balancing cations on the exposed faces of clay particles are supposed to be one of the key factors affecting the specificity of adsorption of gases at clay surfaces. However, the trends characterizing the thermodynamics of gas adsorption, reported for different members of 2:1 phyllosilicate phases, do not systematically follow neither the difference in their layer charge, determining the number of charge-balancing cations, nor the nature of the latter. To better understand the specificity of CH4 and CO2 molecular interactions with different clay phases, the adsorption isotherms were measured for isoionic pure-phase illite and montmorillonite up to pressures of 9 MPa at ambient temperature. For both gases, higher adsorption capacities per unit of specific surface area for montmorillonites in comparison to illites could not be explained by the existing theory relying on the properties of exposed charge-balancing cations on the surface. Instead, the slopes of the isotherms perfectly correlate with the shape of clay particles, characterized by their basal-to-lateral faces’ aspect ratio, which is assessed by derivative isotherm summation (DIS) using argon adsorption at 77 K. Montmorillonite clays, characterized by higher fractions of high-energy hydroxylated particles’ edges (∼45%) in the total specific surface area, featured stronger adsorption interactions with CO2 and CH4 in comparison to illites, for which the contribution of edges to the surface area is only 20%. This introduces a new important factor controlling the mechanism of CH4 and CO2 adsorption by clay minerals.

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Identification of montmorillonite particle edge orientations by atomic-force microscopy

Cited by 21 publications

References 59 publications

Competitive Adsorption Processes at Clay Mineral Surfaces: A Coupled Experimental and Modeling Approach

Competitive Adsorption Processes at Clay Mineral Surfaces: A Coupled Experimental and Modeling Approach

Advances in Clayff Molecular Simulation of Layered and Nanoporous Materials and Their Aqueous Interfaces

Direct Experimental Evidence of the Effects of Clay Particles’ Basal-to-Lateral Surface Ratio on Methane and Carbon Dioxide Adsorption

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