Types Of Clay Minerals Research Articles

Molecular insights into the binding mechanism of strontium and cesium on phyllosilicates with different expandability

The environmental fate of strontium (Sr) and cesium (Cs), as the critical radioactive fission products, have raised significant concerns regarding radioactive waste disposal and environmental protection. The current study investigated the distinction in the binding configurations of Sr2+ and Cs+ on various 2:1 phyllosilicate (illite, vermiculite, and montmorillonite) by combining batch adsorption, sequential extraction, and spectroscopic analyses. The results show that strontium adsorption is strongly influenced by pH as well as ionic strength, while there is no significant variability in strontium adsorption by different types of clay minerals. EXAFS analysis confirms the outer complexation of strontium on the planar sites of the clay minerals, i.e., Sr2+ is surrounded by ~8.0 O atoms, RSr-O ≈ 2.6 Å, and that process is mainly realized by ion exchange. In contrast, Cs+ adsorption was markedly influenced by the variety of clay minerals but less by pH and ionic strength, the presence of humic acid (HA) inhibited Cs+ adsorption. The inner-sphere complexation formed mainly at the frayed edge sites on illite, and interlayer sites on vermiculite and montmorillonite, was the dominant mechanism for Cs+ adsorption. In addition, the collapse of the interlayer space of vermiculite induced by Cs+ adsorption on the interlayer sites was responsible for the more stable and irreversible immobilization. The findings in present work highlighted the significance of prevailed mineral in governing environmental migration risk of radionuclides, the revealed adsorption mechanism and binding configuration of Sr2+ and Cs+ on typical phyllosilicates would be referable in constructing a reliable migration model of Sr2+ and Cs+ in natural media.

Characterization of regolith-hosted rare earth element deposits using reflectance spectroscopy: Framework towards an efficient and reliable field exploration tool

With a growing demand for the rare earth elements (REE), exploration of regolith-hosted REE resources worldwide has been thriving in recent years and development of a rapid and reliable field-based tool will greatly facilitate the survey and exploration. In this study, we use visible and short-wave infrared (VNIR-SWIR) reflectance spectroscopy to comprehensively evaluate the applicability of the technique to explore regolith-hosted REE resources, exemplified by three representative regolith-hosted REE deposits in China. Neodymium among the REE shows reliably detectable spectral features in the VNIR-SWIR spectroscopy down to concentrations of 10–50 ppm in field samples with heterogeneous mineral grain sizes. The Nd spectral intensity of electronic transition at the band of ∼800 nm is correlated with bulk Nd concentrations and can be used as semi-quantitative indicators for the Nd concentrations, thereby the total REE in regolith. Moreover, VNIR-SWIR spectroscopy is demonstrated to be capable of delineating favorable ore-bearing mineralogy by characterizing the abundance and type of clay minerals and Fe (oxyhydr)oxides, and the crystallinity of kaolinite-group minerals. However, the Nd spectral features of samples with high bulk Fe2O3 contents (>3 wt%) are significantly masked due to overlapping by the strong absorption features of ferric (oxyhydr)oxides. VNIR-SWIR spectroscopy is deemed to be applicable to the exploration of regolith-hosted REE resources developed from Fe-poor felsic rocks.

Dissolution Mechanisms and Surface Charge of Clay Mineral Nanoparticles: Insights from Kinetic Monte Carlo Simulations

The widespread use of clay minerals and clays in environmental engineering, industry, medicine, and cosmetics largely stems from their adsorption properties and surface charge, as well as their ability to react with water. The dissolution and growth of minerals as a function of pH are closely related to acid–base reactions at their surface sites and their surface charge. The vivid tapestry of different types of surface sites across different types of clay minerals generates difficulties in experimental studies of structure–property relationships. The aim of this paper is to demonstrate how a mesoscale stochastic kinetic Monte Carlo (kMC) approach altogether with atomistic acid-base models and empirical data can be used for understanding the mechanisms of dissolution and surface charge behavior of clay minerals. The surface charge is modeled based on equilibrium equations for de/protonated site populations, which are defined by the pH and site-specific acidity constants (pKas). Lowered activation energy barriers for these sites in de/protonated states introduce pH-dependent effects into the dissolution kinetics. The V-shaped curve observed in laboratory experiments is reproduced with the new kMC model. A generic rate law for clay mineral dissolution as a function of pH is derived from this study. Thus, the kMC approach can be used as a hypothesis-testing tool for the verification of acid–base models for clay and other minerals and their influence on the kinetics of mineral dissolution and growth.

Micro- and nano-Illite to improve strength of untreated-soil as a nano soil-improvement (NSI) technique

Soil stabilization is a technique of improving the geotechnical properties of soils for various engineering applications. However, conventional stabilizers such as cement and lime have some limitations, such as high cost, environmental impact, and durability issues. Therefore, there is a need for alternative and innovative stabilizers that can overcome these challenges. This study introduces nano-Illite, a type of clay mineral, as a novel and effective soil stabilizer. Nano-Illite can form nano-cementation (NC) in soil, which is a process of enhancing the durability of various building materials. NC is also known as nano soil-improvement (NSI), a technique that has been developed in recent years. Four formulations of micro- and nano-Illite with concentrations of 0, 1, 2, and 3% were separately added to soil samples. The unconfined compressive strength (UCS) and the secant modulus at 50% of peak stress (E50) of the treated samples were measured and compared with the untreated samples. The results showed that 3% nano-Illite increased the UCS of soil by more than 2.2 times and the E50 by more than 1.5 times after 7 days of curing. Micro-Illite also improved the UCS and E50 of soil, but to a lesser extent. X-ray fluorescence (XRF), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses revealed the micro- and nano-structures of the soil specimens and the performance of Illite as a nano-additive. This research demonstrates the effectiveness of nano-Illite in soil improvement as a NSI technique, and its potential to replace or reduce the use of conventional stabilizers. This study also contributes to the understanding of the mechanisms and factors that influence the NC process in soil.

Study on the adsorption/desorption characteristics and dynamic diffusion mechanism of rare earth hydrated ions on the kaolinite (001) surface

Coal gangue (CG) contains abundant rare earth elements (REEs), which is a potential REE resource. REEs are mainly present in clay minerals as hydrates. The adsorption, desorption, and diffusion of REEs-hydrates on the surface of clay minerals are the key to regulating the leaching effect of REEs. The paper focuses on the typical clay minerals kaolinite and REEs-hydrates and combines quantum mechanics and molecular dynamics methods to systematically study the adsorption, desorption, and dynamic diffusion behavior of REEs-hydrates in acid solution. The research results indicate that stable REEs-hydrates La(H2O)9 and Y(H2O)7 are formed, with ion bonds between REEs and water molecules. La(H2O)9 and Y(H2O)7 mainly interact with the kaolinite (001) surface through hydrogen bonding. Competitive adsorption is formed between water molecules, hydrated hydrogen ions, and REEs-hydrates. Water molecules and hydrated hydrogen ions occupy the adsorption active sites of REEs-hydrates and form a dense water molecular layer on the surface. The distance between H3O+ and REEs-hydrates and the number of H3O+ in the solvent layer affect the desorption and diffusion behavior of hydrates. The bonding law, dynamic desorption, and diffusion mechanism of REEs-hydrates can provide meaningful references for selective leaching of REEs from CG.

How did ancient human activities influence the properties and development of soil?—a case study of the Yangshao Village cultural relic site, Henan Province

Introduction: What were the effects of paleoanthropogenic activities on the physicochemical properties and degree of the development of soil? To search for this answer, we can not only understand the different types of ancient human activities but also explore the intensity and characteristics of the activities.Methods: In this study, soil samples from different soil layers and two profiles in the Yangshao Village cultural site in Henan Province were collected. Their physicochemical properties and the sporophyte phyllosilicates they contain were analyzed and compared.Results: We found that the paleoanthropogenic activities started in the relatively low-lying area, in which the slash-and-burn activities resulted in the soil being filled with intrusions such as charcoal debris and ceramic shards. At the same time, the coarse-grained matter was affected by the plowing activities and mostly decomposed into fine particles, and the content of clay particles reached an extreme value. The total nitrogen, phosphorus, and calcium carbonate content exceeded the average value of the natural profile, indicating that ancient humans had used human and animal feces to a certain extent to restore the fertility of arable land.Discussion: Overall, ancient human activities hindered the development of the soil, especially the ground created due to habitation activities. From the type and content of clay minerals, it could be seen that the soil in this layer has been transported from other places, has a high content of clay particles, and has experienced fire baking. It was assumed that the ground was used to cover the grain or bury the garbage and lay with clay in order to achieve the effect of sealing. As a result, the soil voids and structure had been damaged to some extent, which prevented the downward leaching or precipitation of soil particles and minerals to a certain extent, thus affecting soil development.

Influence of alternating electric field on electrorheological effect of aqueous dispersions of stevensite

Upon deionization of the aqueous dispersion of stevensite, a type of smectite clay minerals, a low-viscosity colorless transparent dispersion is obtained. The phenomenon known as the electrorheological (ER) effect has been previously reported when a weak electric field of several V/mm is applied to the stevensite aqueous dispersion. In this study, the influence of the waveform and frequency of the electric field was investigated while keeping the electric field intensity constant. It was observed that as the acceleration of the applied electric field intensity increased, the stress response to the electric field improved. Increasing the frequency of the electric field led to a reduction in the induced stress; however, it improved the response rate of stress. It has been indicated that even at higher electric field frequencies, the potential for observing the ER effect exists with higher electric field intensities. Maintaining a low electrolyte concentration may facilitate the development of novel ER fluids capable of instantaneously responding to the application or removal of electric fields.

New computational method for calculating of water droplet–clay contact angles: Based on molecular dynamics

The measurement of the water contact angle (θ) on the surface of clay minerals poses a significant challenge due to their microscopic particle sizes ranging from micrometers to nanometers and their extensive specific surface areas. We introduce an advanced computational framework based on molecular dynamics simulations. This framework leverages the coordination number (CN) differences of the water molecules and effectively eliminates the gaseous water molecules in the droplet equilibrium system. Additionally, our framework uses an alpha-shaped probe ball to accurately determine the three-dimensional (3D) coordinates of the droplet interface and utilizes a feed-forward neural network (FFNN) to optimize the objective function of the 3D-interface; this ensures highly accurate characterization of the interface contour and an accurate computation of θ. Our approach exhibits outstanding performance in typical clay mineral surface-water wetting systems; it significantly overcomes the limitations of the transformed cylindrical coordinate system algorithm and accurately captures the wettability variations under complex environmental conditions. This new θ computational framework provides crucial assistance for the in-depth exploration of the wettability characteristics of clay minerals in complex environments.

Impact of Clay Mineral Type on Rock Properties under Drying and Wetting Cycles

Impact of Clay Mineral Type on Rock Properties under Drying and Wetting Cycles

An overview of halloysite mineral

Halloysite is a type of clay mineral found in the kaolin group together with kaolinite, dickite, and nacrite minerals. Kaolinite is the most common mineral in this group, while dickite, nacrite, and halloysite are rarer. Although halloysite is primarily used in ceramic production, application in other industries is increasing and gaining economic value due to its unique properties. The use of halloysite is determined by the degree of purity and the properties of the nano-sized tubular structure. Naturally obtained halloysite mineral has a key position in the field of nanotechnology due to its unique physicochemical properties originating from its tubular structure. Also, due to its reserves in many parts of the world, halloysite is a more economical material for the sectors compared to artificially produced nanomaterials. And, they find many different application areas because of these features (morphological and physicochemical). Halloysite reserves known in Türkiye are located in the Çanakkale and Balıkesir regions. Although there are many useful studies on halloysite in different, additional studies are needed to understand the nano-sized properties of halloysite ore and to ensure its use that will provide maximum benefit. This study aimed to contribute to the studies on halloysite in terms of literature by compiling studies on the characterization of halloysite minerals, reserve information, physicochemical properties, enrichment methods, and usage areas.

Facies analysis and paleoenvironment of the Poti Formation in the Itaueira and Floriano region: Contribution to the Carboniferous depositional history of the Parnaíba basin

The Parnaíba intracratonic basin exhibits sedimentation that reflects the different evolutionary stages of climate and paleogeography in the West Gondwana supercontinent. In this regard, we conducted a study comprising the Poti Formation in the southeast of Itaueira and Floriano regions in Piauí State, within the Parnaíba Basin. The facies analysis enabled the establishment of the depositional model for the study area, comprising ten sedimentary facies separated into two facies associations (FA) deposited in a shallow platform environment dominated by storm waves: Upper Shoreface (FA-1) and Lower Shoreface/Offshore transition (FA-2). It was possible to determine that the wave base line constantly varied, and a high-energy event provided the deposition of sediments with fine-to coarse-grained sandstone from FA-1 over those of FA-2, creating a first-order erosive surface (surf diastema) with a gradient varying from 40 to 45° that limits the two distinct facies association. This sedimentary event resulted in the excavation of the muddy offshore sediments by the lower shoreface, resulting in coarsening- and thickening-upward sandstones lying mostly under fine-grained sandstone with hummocky cross-stratifications. In the paleogeographic context, the cross-stratification paleocurrent indicates a direction towards the NW and, to a lesser extent, the SW. This direction suggests a connection between the epicontinental sea formed in the Parnaíba Basin and the paleosea of Tethys in the Late Carboniferous. Petrographic analysis classified the sandstones as subarkose and quartzarenite. This study employed petrography, X-ray diffractometry, architectural elements, and facies analysis to make inferences about the depositional system, climate, and geomorphology of the storm and wave-dominated deposits of the Poti Formation. The occurrence of kaolinite and illite in the studied deposits are typical clay minerals of humid and hot (dry) climatic conditions, respectively. Therefore, the overall data indicates a shift from retrogradational to progradational deposits that records changes in facies association and climate conditions in the Late Carboniferous.

Mechanistic study of the effect of clay hydration swelling on CH4/CO2 competitive adsorption

The study on the hydration swelling mechanism of different types of shale clay minerals and the influence of water content on the adsorption characteristics of CH4/CO2 is of great significance for CO2 storage in shale reservoirs and enhanced shale gas recovery. Molecular dynamics (MD) and Grand Canonical Monte Carlo (GCMC) were employed to establish different types of shale clay minerals (sodium montmorillonite, calcium montmorillonite, and illite). Hydration swelling simulations were performed at water contents ranging from 0.0 wt% to 20.7 wt%. Additionally, CH4 adsorption and CH4/CO2 competitive adsorption simulations were conducted at varying water densities. The effects of clay mineral type and water content on hydration swelling degree, gas adsorption capacity, and CO2/CH4 adsorption selectivity were analyzed. The simulation results indicate that variations in surface charge enrichment and interlayer cationic ionic radius account for the differences in hydration degree. Under the same water content, the hydration degree of the three clay minerals follows the order: sodium montmorillonite > illite > calcium montmorillonite. The gas adsorption capacity of clay minerals decreases with the increase of water content, and the greater the water content, the smaller the reduction range. With the increase of water content, the adsorption selectivity of CO2/CH4 first decreased and then increased, and the increasing range of different clay minerals was sodium montmorillonite > illite > Calcium montmorillonite. The research results of this paper have a certain reference value for the reasonable development of shale gas and the study of CO2 storage in shale.

Effect of clay crystal structure on froth rheology in flotation

It has been well acknowledged that clay minerals could impose deleterious effects on flotation performance by affecting pulp rheology. To date, it is still not clear regarding the role of clay minerals in influencing froth rheology which has been increasingly recognized as an important froth property in determining flotation performance. Hence, this work selected three typical clay minerals with different characteristics to study their impacts on froth rheology: montmorillonite, kaolinite and talc. The results showed that the clay minerals showed different froth rheological behaviors with increasing the solids concentration in the feed from 1 wt% to 9 wt%. For montmorillonite, the froth viscosity decreased first and then increased, reaching a lowest viscosity at 5 wt%. The froth viscosity continuously decreased for kaolinite while it kept increasing for talc over the solids concentration in the feed. In addition, talc generated much more viscous froths than the other two clays. The different varying behaviors of froth viscosity among the three clays were related to clay crystal structure and surface hydrophobicity which ultimately determined froth properties. It is believed that the outcomes of this study could facilitate the flotation optimization of complex ores with the presence of clay minerals.

Viscoelasticity modeling of clay minerals by dynamic viscoelasticity measurement and its implications for earthquake faulting

Slip on clay fault planes at shallow depths in the seismogenic zone could be controlled by their rheology as well as their frictional properties; however, the rheological nature of clay faults is still an open question. Investigating the rheological properties of clay minerals is essential for understanding and modeling shallow earthquake faulting. Here, we perform dynamic viscoelasticity measurements on three clay minerals, namely kaolinite, illite, and smectite, wetted with water using a custom-made high pressure, high temperature rheometer. Our results confirm that the rheological properties resulting from the microstructure of clay minerals depend on the oscillation frequency, oscillation amplitude, temperature, and amount of water contained. In addition, the rheological properties vary systematically with the type of clay mineral. This suggests that the viscoelastic behavior of earthquake faults varies with the type of clay minerals present.

The Scenario of Clays and Clay Minerals Use in Cosmetics/Dermocosmetics

The use of clays in beauty care comes from ancient times, with therapeutic use since prehistory, and it is considerably relevant in the current cosmetic industry worldwide. In our review, we described types of clay and clay minerals used in cosmetics and dermocosmetics, compositions, usages as active compounds and cosmetic ingredients/starting materials, and observations about formulation techniques. From this review, we observed that although much scientific and specialized literature has reported the characterization of clays, only some involved efficacy tests when incorporated into cosmetic products, mainly concerning haircare applications. Our review could be considered and encouraged in the coming years to provide scientific and technical information for the cosmetic industry regarding the multifunctional use of clays and clay minerals.

Mineralogical properties of pyroclastic materials from Mount Merapi, Indonesia

Mount Merapi, located in Indonesia, is known as one of the most active volcanoes globally, often resulting in volcanic eruptions that produce pyroclastic materials. These materials from Mount Merapi’s eruptions have the potential to influence soil fertility in areas affected by the volcanic activities. This study aims to analyze the mineralogical properties of pyroclastic materials from Mount Merapi. The methodology involves collecting pyroclastic material samples from the 2010 eruption of Mount Merapi, followed by analysis using various mineralogical techniques such as polarized microscopy, X-ray diffraction, petrographic analysis, and wet chemical analysis. The findings offer detailed insights into the mineral composition, types of clay minerals, overall elemental presence, and the rock types forming these minerals in the pyroclastic materials. Variations in mineral composition are observed in the pyroclastic materials from Mount Merapi. Predominant minerals, including the plagioclase, pyroxene, and hornblende groups, are distinctly identified. These minerals’ presence suggests their susceptibility to weathering, categorized as easily weatherable minerals. This tendency for weathering is shown by the presence of elements like Na, Ca, and Mg in these minerals, which are crucial macro-nutrients for plant growth.

Strength, leaching characteristics and microstructure of CGF+P all-solid-waste binder solidification/stabilization Cu(Ⅱ) contaminated soil

Utilizing solid waste-based binder to solidify/stabilize (S/S) heavy metal contaminated soils is a sustainable approach. This paper implemented microscopic tests on Cu(II)-doped paste and macro-microscopic tests on S/S Cu(II) contaminated pure clay-particles soil (P-CS), pure silt-particles soil (P-ST), pure sand-particles soil (P-SD), and their mixed soil (CSSM), respectively, with CGF+P all-solid-waste binders (abbreviated as CGF+P binders) composed of calcium carbide residue (CCR), ground granulated blast furnace slag (GGBS), fly ash (FA), and phosphogypsum (PG). The results showed that the clay-minerals in soil determine the S/S efficiency, and Cu(II) threshold content exist in the presence of clay-minerals and absent without clay-minerals. The strength of P-CS and CSSM containing clay-minerals first increased and then decreased with the increase of Cu(II) content, while the leached Cu(Ⅱ) were lower than 2 mg/kg. The strength of P-ST and P-SD without clay-minerals decreased gradually, and the leached Cu(Ⅱ) concentration far higher than 2 mg/kg. Cu(II) ions are immobilized by CGF+P paste and clay-minerals in soil. The S/S mechanism of Cu(II) by CGF+P binders rely on precipitation, adsorption, encapsulation, chemical compound, and ion exchange, and the immobilized mechanism of Cu(II) by clay-minerals through electrostatic attraction, ion exchange, and physical adsorption. However, the binder paste and clay-minerals have the immobilization capacity on Cu(II) ions, is related to the component of the binder and the type of clay-minerals, respectively. The findings provided useful reference for the design and development of solid waste-based binders suitable for S/S heavy metal contaminated soils.

The Ability of Some Clay Minerals and Activated Charcoal to Reduce the Negative Effects of Aflatoxin B1, a Contaminant of Broiler Diet

The research was conducted to determine the effect of four types of clay minerals (Iraqi bentonite, English bentonite, Turkish bentonite, and Iraqi kaolin) and activated charcoal on reducing the negative effects of aflatoxin B1, which contaminates poultry feed at a concentration of 350 ppb. The results showed that the average bird weight reached 1134.5 grams in the aflatoxin treatment alone, with a significant difference compared to the control treatment (1690 grams). Adding English bentonite to the contaminated feed was efficient in reducing the impact of aflatoxin, as the bird weight did not differ significantly from the control treatment and reached 1686.9 grams, followed by Turkish bentonite, with an average bird weight of 1618.8 grams, and then Iraqi bentonite with an average weight of 1533.2 grams. The results also indicated that the relative weights of the liver, spleen, and pancreas increased in birds treated with aflatoxin alone. However, the addition of different clay minerals and activated charcoal led to a decrease in the relative weights of the internal organs. The relative weight of the heart and Proventriculus was not affected by the addition of aflatoxin to the feed. Blood analysis results showed a significant decrease in protein and albumin concentrations in the blood of birds treated with aflatoxin alone compared to the control treatment. Additionally, the different additions of clay minerals and activated charcoal had a positive effect on protein concentrations in the blood. Aflatoxin also caused a decrease in blood hemoglobin and red blood cell counts, an increase in white blood cell counts, and an increase in the Neutrophil/Lymphocyte index in birds treated with aflatoxin. However, blood viscosity did not change between the aflatoxin treatment and the other treatments.

Hysteresis in Soil, Its Causes and Influences

Soil hysteresis is a natural phenomenon that occurs in soil water retention curve (SWRC) and soil water characteristic curve (SWCC), the mismatch of the drying (drainage or desorption) and wetting (sorption or adsorption) curves in each curve is called hysteresis in soil, i.e., At any potential (Ψ), there is a discrepancy between the soil water content (Θ or ű) in the curve of desorption and adsorption, this indicates that the amounts of water collected during the desorption cycle are not the same as the amount of water for adsorption the soil at the same applied pressure (suction Ψ). So, this relationship between soil water content (Θ or ű) versus soil water potential (Ψ) is non-unique. The difference is caused by a number of mechanisms, including: Contact Angle (θ), Adsorption, Bubble-form, Matric potential, Ink-Bottle Effect, Entrapped Air, Wetting and Drying History and Pore Size... etc. The explanations concern both (water and soil). Soil hysteresis has a degree, that varies depending on the type of clay minerals and pore size... etc. In this review paper, what are the causes of soil hysteresis, the hysteresis degree, and what does it influence? will be discussed.

Efficiency of Some Clays and Organic Materials on the Reduction of Aflatoxin B1 Produced from Isolates of the Fungus Aspergillus flavus Contaminating Corn Grains

The study was conducted to evaluate the effectiveness of certain types of clay minerals, activated charcoal made from common reed and date palm kernel, in reducing the levels of aflatoxin B1(AFB1) produced by Aspergillus flavus that contaminated corn grains in a liquid medium, Yeast Extract Sucrose (YES). The results showed the presence of nine species of fungal genera that contaminated corn grains, with the Aspergillus spp being the most predominant, accounting for 42%, followed by the Penicillium spp with 27%, and the Fusarium spp with a 21%. The genera Rhizopus spp, Mucor spp, and Cladosporium spp had a prevalence of 5%, 4%, and 1%, respectively. The results of the thin-layer chromatography (TLC) test, which was used to isolate A. flavus fungi from corn grains and detect the presence of AFB1, showed variations in their ability to produce AFB1. Seventy-five percent of the diagnosed A. flavus isolates showed the ability to produce AFB1. The results indicated that all types of minerals used in the study were effective in reducing the levels of AFB1 in liquid media. Top of Form Similarly, activated charcoal from common reed showed a high potential for AFB1 reduction, where the highest reduction percentage was 93.90% for the activated charcoal from fermented reed at a concentration of 30 mgml−1.