Characterizing the surface charge of clay minerals with Atomic Force Microscope (AFM)

Guo, Yuan; Yu, Xiong

doi:10.3934/matersci.2017.3.582

Cited by 36 publications

(11 citation statements)

References 32 publications

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“…Specifically, there should not be any pH buffering in the background solution. Atomic force microscopy probing of surface potential on montmorillonite in 1 mM NaCl postulates the surface potential value of � À 63 mV, [54] which is quite close by magnitude to the predicted potential 69 mV 2 at the distance 14.8 nm at which the predicted diffuse proton concentration attains the same value as the background electrolyte in the cited experiment (Figure 4c "only surface layer, no gel" pK 3; this curve corresponds to a planar solid electrolyte with relatively far-spanning open space in front of it, which is an adequate model for the cited AFM experiment). Known data concerning typical surface area, [55] acid sites content and their strength [56] in montmorillonite suggest that our model's numeric parameters like acid sites surface concentration and their pK (see caption of Figure 4) are reasonably accurate to describe the real mineral.…”

Section: Resultsmentioning

confidence: 99%

Unidimensional Approximation of the Diffuse Electrical Layer in the Inner Volume of Solid Electrolyte Grains in the Absence of Background Ions

Tarabanko

Тaran

2020

ChemPhysChem

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In this paper we continue working on our theory of electrical double layers resulting exclusively from dissociation of a solid electrolyte, which we previously proposed as a medium for catalytic interaction between solid cellulose and solid acid catalysts of hydrolysis. Two theoretical unidimensional models of the inner grain volume are considered: an infinitely long cylindrical pore, and a gel electrolyte near a grain outer surface. Despite the model simplicity, the predictions for the cylindrical pore case are in semi‐quantitative agreement with literature data on electroosmotic experiments, adequately explaining high proton selectivity of sulfonic membranes, and decline of such selectivity at high background acid concentration. The gel model predicts less concentrated diffuse layer in comparison to electrolytes with impenetrable skeleton (e. g., sulfonated carbons). This suggests limited suitability of gel electrolytes as catalysts if a substrate cannot diffuse into the gel bulk and the reaction is thereby spatially limited to the near‐surface region, for example if a substrate is solid like aforementioned cellulose.

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Section: Resultsmentioning

confidence: 99%

Unidimensional Approximation of the Diffuse Electrical Layer in the Inner Volume of Solid Electrolyte Grains in the Absence of Background Ions

Tarabanko

Тaran

2020

ChemPhysChem

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“…Smectite belongs to the class of aluminum phyllosilicates. Generally, the surface charge of clay minerals at neutral pH is negative 41 because of the presence of dissociated surface hydroxyl groups. The sensors consist of an AT-cut quartz crystal disk (14 mm in diameter) with metal electrodes deposited on both sides.…”

Section: Experimental Methodsmentioning

confidence: 99%

Understanding the Cation-Dependent Surfactant Adsorption on Clay Minerals in Oil Recovery

et al. 2019

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Surfactants have the ability to mobilize residual oil trapped in pore spaces of matrix rocks by lowering the oil− water interfacial tension, resulting in a higher oil recovery. However, the loss of surfactants by adsorption onto the rock surface has become a major concern that reduces the efficiency of the surfactant flooding process. In this study, the adsorption behavior of an anionic surfactant to a clay mineral surface was investigated by quartz crystal microbalance with dissipation monitoring upon variations with different cation conditions. Through recording the change of frequency and dissipation of clay-modified sensors, it allows us to do a real-time quantitative analysis of the surfactant adsorption with nanogram sensitivity. The results revealed that the surfactant adsorption increased in a Ca 2+ -containing solution with increasing pH from 6 to 11, whereas from a Na + -containing solution, more adsorption occurred at acidic conditions. The adsorbed amount went through a maximum (∼200 mM) as a function of the Ca 2+ concentration, and the Voigt model suggested that multilayer adsorption of surfactants could be as many as 4−6 monolayers. Using mixed cation (Ca 2+ and Na + ) solutions, the amount of adsorbed surfactant decreased linearly with decreasing fraction of CaCl 2 , but Na + competed for about ∼30% adsorption sites. The importance of the presence of CaCl 2 for the surfactant adsorption was stressed in high-salinity and low-salinity solutions in the presence and absence of Ca 2+ . Furthermore, increasing the temperature from 23 to 65 °C shows first a small increase of surfactant adsorption followed by a reduction of about 20%. The obtained results contribute to a better understanding of surfactant adsorption on clay surfaces and a guide to optimal flooding conditions with reduced surfactant loss.

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“…The surface chemistry of clay minerals can now be described by two processes like physisorption and chemisorption of molecules and ions which takes place in the interlayer space and at the edges of the clay mineral layers. For better description of the surface properties, surface electric properties like surface potential and surface charge density are required [71,72].…”

Section: Surface Charge Propertiesmentioning

confidence: 99%

Basics of Clay Minerals and Their Characteristic Properties

Kumari¹,

Mohan²

2021

Clay and Clay Minerals

160

106

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Clay minerals such as kaolinite, smectite, chlorite, micas are main components of raw materials of clay and formed in presence of water. A large number of clays used to form the different structure which completely depends on their mining source. They are known as hydrous phyllosilicate having silica, alumina and water with variable amount of inorganic ions like Mg2+, Na+, Ca2+ which are found either in interlayer space or on the planetary surface. Clay minerals are described by presence of two-dimensional sheets, tetrahedral (SiO4) and octahedral (Al2O3). There are different clay minerals which are categorized based on presence of tetrahedral and octahedral layer in their structure like kaolinite (1:1 of tetrahedral and octahedral layers), smectite group of clay minerals (2:1 of tetrahedral and octahedral layers) and chlorite (2:1:1 of tetrahedral, octahedral and octahedral layers). The particle size of clay minerals is <2microns which can be present in form of plastic in presence of water and solidified when dried. The small size and their distinctive crystal structure make clay minerals very special with their unique properties including high cation exchange capacity, swelling behavior, specific surface area, adsorption capacity, etc. which are described in this chapter. Due to all these unique properties, clay minerals are gaining interest in different fields.

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Characterizing the surface charge of clay minerals with Atomic Force Microscope (AFM)

Cited by 36 publications

References 32 publications

Unidimensional Approximation of the Diffuse Electrical Layer in the Inner Volume of Solid Electrolyte Grains in the Absence of Background Ions

Unidimensional Approximation of the Diffuse Electrical Layer in the Inner Volume of Solid Electrolyte Grains in the Absence of Background Ions

Understanding the Cation-Dependent Surfactant Adsorption on Clay Minerals in Oil Recovery

Basics of Clay Minerals and Their Characteristic Properties

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