Modification Of Clay Minerals Research Articles

Application of Organoclays in Oil-Based Drilling Fluids: A Review.

Organoclays (OCs), formed by surface modification of clay minerals using organic compounds, are typical additives for providing rheology for oil-based drilling fluids (OBDFs). There are different studies on the effect of OCs on the rheological properties of oil-based systems under high-pressure, high-temperature (HPHT) conditions, but finding new OCs as rheology control agents is attractive for drilling fluid engineers. This work reviews different OCs used in OBDFs, namely, organo-montmorillonite (OMMT), organo-sepiolite (OSEP), and organo-palygorskite (OPAL). Furthermore, the structure of OCs in OBDFs, their rheological properties, and the thermal stability of OCs were investigated. Besides, the role of fibrous and layered OCs in enhancing the rheological properties of OBDFs is illustrated. Finally, the synergistic use of different OCs to enhance the thermal stability and rheological properties of the OBDFs is presented. The study highlights research gaps and recommendations for research approaches and potential areas that need further investigation. The application of OCs in OBDFs is a wide field and has huge potential to be developed. The use of OCs in OBDFs will promote development in the oil and gas industry.

Clay/nanocomposite hydrogels: In review

The development of advanced materials those are stronger, more rigid, lighter, hotter and self-renewable than existing materials has been the rising point of many research studies conducted in recent years. Within this scope, the interest to production of nanostructured materials is received considerable attention worldwide due to their potential positive contribution to wide variety of technological areas such as electronics, catalysis, adsorbents, ceramics, magnetic data storage, structural components etc. In these efforts polymer nanocomposites as the form of hydrogels, reinforced with well-dispersed layered silicate, typically montmorillonite can be given as a one of the promising composite material. However, long-standing problems for polymer-clay nanocomposites include actual exfoliation of clay particles in discrete layers, uniform distribution of clay layers throughout the polymer, and randomness of clay sequences. For the exfoliation of clay particles, although the chemical modification of clay minerals in aqueous media is the well-known and more general way applied by researchers, the physical pathway method performed by high-energy ball mills is also gaining increasing attention as an alternative pretreatment way. Grinding of crushed materials is one of the key processes in the mineral and cement industry, but the increased concern on the preparation of fine-grained powders (nano powders) or the manufacture of composites with desirable properties, especially performed with use of high-energy ball mills, has led to significantly widen the usage field of grinding. Undoubtedly, the main reason for these efforts is to improve the performance of existing materials. In this paper the fundamental concepts, classification, physical and chemical characteristics and the production methods of clay/polymer nanocomposites was briefly reviewed base on the composite hydrogel. Particular attention was paid to the pre-treatment (exfoliation) of clays with high-energy ball mills, which is increasingly being accepted as an alternative method to eliminate the negative effects of chemical treatment in some composite forms.

An Investigative Study on the Structural, Thermal and Mechanical Properties of Clay-Based PVC Polymer Composite Films.

The present study aims to explore the impact of pristine and surfactant-modified clays (montmorillonite, bentonite and vermiculite) on the thermomechanical properties of a poly (vinyl chloride) (PVC) polymer film. Initially, clay was modified by employing the ion exchange method. The modification of clay minerals was confirmed by the XRD pattern and thermogravimetric analysis. Pristine PVC polymer film and clay (montmorillonite, bentonite and vermiculite)-based PVC polymer composite films were fabricated using solution casting. The ideal dispersion of surfactant-modified organo-clays was observed in the PVC polymer matrix due to the hydrophobic nature of modified clays. The resultant pure polymer film and clay polymer composite film were characterized using XRD and TGA, and their mechanical properties were determined using a tensile strength tester and Durometer. From the XRD pattern, the intercalation of the PVC polymer film was found in the interlayer of organo-clay while exfoliation or partial intercalation and exfoliation were observed for pristine clay mineral-based PVC polymer composite films. Thermal analysis indicated a lowering of the decomposition temperature of the composite film as clay promotes the thermal degradation temperature of PVC. Improvement in the tensile strength and hardness was found to be more frequent in the case of organo-clay-based PVC polymer films, which is only due to the hydrophobic nature of organ clays, resulting in greater compatibility with the polymer matrix.

Research Progress on the Modification Methods of Clay Minerals

Clay minerals are widely distributed in nature, and their applications have been rapidly developed in the last decade or so due to their unique physical and chemical properties. Since the most researched is the modification of clay minerals, this paper introduces the types of clay, basic structural characteristics and common modification methods. The methods of modified clay include high-temperature excitation and acid-base excitation methods to stimulate the activity of clay minerals, as well as interlayer ion exchange modification methods, clay surface grafting techniques such as sol-gel method, surface hydroxyl grafting modification and other methods, and also introduces the intercalation methods, including solution intercalation method, In situ polymerization intercalation method, etc. The applications and developments of clay minerals are summarized, from traditional industrial applications to environmental protection and high-tech nanomaterials, mainly in the automotive industry, environment-friendly materials and catalysts.

Micro mechanism of latent heat enhancement of polyethylene glycol/aminated modified palygorskite composite phase change materials

Surface functional modification of clay minerals showed a positive effect on promoting phase change behavior and improving heat storage characteristic of phase change material (PCM). Currently, there was a lack of quantitative evidence to explain the micro mechanism between surface functional modification and latent heat enhancement. In this work, the dopamine-modified palygorskite/polyethylene glycol (MPP) composite PCMs were prepared and their latent heat enhanced micro mechanism was studied in depth based on density functional theory (DFT) calculations. Due to the strong surface interaction, the phase change behavior of palygorskite/polyethylene glycol composite PCMs was strongly restricted so that no latent heat was released when the content of polyethylene glycol was <50 wt%. After dopamine modification, the latent heat (> 37.63 J/g) of MPP was released when the content of polyethylene glycol was higher than 30 wt%, indicating that the surface interaction was weakened. The DFT calculation results revealed that before and after dopamine modification, the surface interaction changed from weak SiO chemical bonds to no combination approaches and the interaction energy sharply dropped from 195.25 eV to 0.40 eV, demonstrating that the surface interaction between polyethylene glycol and palygorskite was greatly reduced, which was further confirmed by the crystallization and heat storage/release results, which was responsible for the promoted phase change behavior and enhanced latent heat. Furthermore, the MPP exhibited excellent chemical compatibility and acceptable thermal stability. This work was of great significance in revealing the inner relationship between the microstructure and property enhancement of clay minerals-based composite PCMs.

Immobilization mechanism of Cd2+/HCrO4-/CrO42- ions and carboxin on montmorillonite modified with Rhizobium leguminosarum bv. trifolii exopolysaccharide

The modification of clay minerals by exopolysaccharides (EPSs) may significantly increase their adsorption capacity. Therefore, this study focused on the impact of the EPS synthesised by the soil bacterium Rhizobium leguminosarum bv. trifolii on the adsorptive features of montmorillonite relative to two heavy metal ions (cadmium/Cd(II) and chromium/Cr(VI)) and a pesticide (carboxin). The characterization of montmorillonite was carried out using various methods: X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy. The adsorption/desorption data were modelled using theoretical equations (Langmuir-Freundlich, Redlich-Peterson, etc.). The obtained results showed that EPS promoted the accumulation of heavy metals on the clay mineral and, simultaneously, contributed to a lower degree of their desorption. This resulted from complexation between the biopolymer and the Cd(II)/Cr(VI) ions. After montmorillonite modification with 100 mg/L EPS, the maximum noted growth in Cd(II) adsorption was 26.10%, whereas it was 20.30% for Cr(VI). The adsorbed amounts of Cd(II) and Cr(VI) were then 24.24 and 14.45 mg/g, respectively. In the case of carboxin, the EPS effect on its adsorption/desorption rates was opposite – its adsorption level decreasing by 10.80%, was 0.27 mg/g. Thus, the presence of EPS-producing bacteria could reduce the bioavailability of the heavy metals, but not of the selected pesticide.

Oleophobic modification of clay minerals to improve encapsulation ratios of shape-stabilized phase change materials: A universal method

Liquid-solid phase change materials (PCMs) show reversible storage and release of latent heat, which has attracted extensive interests in applications for thermal energy storage. However, stubborn leakage issue may cause corrosion and extra thermal resistance. The non-wettability of melted paraffin on the oleophobic surface of diatomite has been reported by authors earlier, and the result showed that the encapsulation ratio (84.5%) of diatomite@paraffin shape-stabilized PCM greatly increased. Here, in order to prove this method equally applicable to other PCMs and porous natural clay minerals, diatomite and sepiolite were oleophobically modified to encapsulate melted stearic acid and paraffin, to form shape-stabilized PCMs. The results showed that the encapsulation ratios of 67.8% and 56.6% for diatomite@stearic acid and sepiolite@paraffin were higher than that reported in the references (28.9% and 36.8%). In addition, the encapsulation ratios of diatomite-based shape-stabilized PCMs can be also increased using different PCMs, such as n-octadecane and polyethylene glycol via the same approach. Therefore, this is a universal method for improving encapsulation ratios of shape-stabilized PCMs.

Organic Reactions Using Clay and Clay-Supported Catalysts: A Survey of Recent Literature

Clays and modified or supported clays have become some of the widely used catalysts for a variety of organic reactions, due to their easy structural modifications and activation, low-cost, eco-friendly nature, ready availability, ability to act as acidic or basic catalyst without being corrosive. The present review is a survey of the literature dealing with most of the important work on clay catalysed organic reactions published during the period 2011–2020, and is a sequel to our previous review covering the literature of 2001–2010. The review consists of various segments starting with introduction that briefly mentions the structure and modification of clay minerals, particularly the most widely used montmorillonite, followed by organic reactions such as condensation, addition, substitution, elimination, reduction, oxidation, wastewater remediation, biodiesel synthesis and a few miscellaneous reactions that are accomplished using these catalysts. Among these, biodiesel synthesis and remediation are widely investigated transformations, and find practical applications.

Fe(III)-polyhydroxy cations supported onto K10 montmorillonite for removal of phosphate from waters

Since phosphate is strongly related to eutrophication of environmental waters, several research groups quest for materials that can efficiently remove phosphate from wastewaters before it contaminates lakes and reservoirs. In the present work, a commercial clay mineral (K10 montmorillonite) modified with Fe3+ polyhydroxy cations was investigated as an adsorbent for phosphate. The incorporation of the polycations did not alter the main conformational characteristics of the montmorillonite, as verified by specific surface area measurements, X-ray diffractometry, FTIR, electron microscopy, and zeta potential titrations. On the other hand, the materials supporting Fe3+ polyhydroxy cations exhibited a significant enhancement of adsorption capacity, as determined by Langmuir-Freundlich isotherms, from 39 ± 2 to 104 ± 15 μmol g−1. The different ratios of OH− to Fe3+ did not affect the adsorption capacities. The adsorption kinetics was best described by the pseudo 2nd order model, approaching the equilibrium after 120 min of contact time. A variation of pH between 4.6 and 8.5 did not affect the adsorption percentages. The adsorption capacities increased with the increase of the ionic strength, thus suggesting that the formation of inner-sphere complexes prevails over electrostatic interactions as the adsorption mechanism. The materials removed phosphate from three polluted water samples having phosphate concentrations between 0.0919 and 1.211 mg L−1. The remaining phosphate concentration was below the limit of quantification of the analytical method (0.063 mg L−1 in P, or 2.0 μmol L−1). The presence of 10 mg L−1 humic of fulvic acid did not affect the performance of the materials. In conclusion, the modification of clay minerals with Fe3+ polyhydroxy cations is useful in producing low-cost adsorbents for phosphate.

A review on the application of clay minerals as heavy metal adsorbents for remediation purposes

Abstract Clay minerals are affordable, abundant, naturally occurring minerals found in many parts of the world that have been used effectively for remediation of many contaminants. This review article is aimed at studies involving the use of clay minerals for the remediation of soils and water contaminated with heavy metals. All relevant scientific literature using science direct online database from the year 2000 till 2019 were evaluated. The review highlighted the properties of clay minerals which make them good adsorbents and the processes necessary for adsorption to take place. It revealed that clay minerals are quite effective for remediation purposes, confirmed that clay minerals are very affordable, reliable, and environmentally friendly remediation materials for heavy metal contaminated media. Also, several methods are available for the modification of clay minerals in order to increase their adsorption capacity. However, in order to establish the use of clay minerals as heavy metal remediation materials compared to other established methods, more investigations are required, to determine the best modification type for clay minerals as well as the standard dosage of clay minerals required for the adsorption of heavy metals.

Calcination Enhances the Aflatoxin and Zearalenone Binding Efficiency of a Tunisian Clay.

Clays are known to have promising adsorbing characteristics, and are used as feed additives to overcome the negative effects of mycotoxicosis in livestock farming. Modification of clay minerals by heat treatment, also called calcination, can alter their adsorption characteristics. Little information, however, is available on the effect of calcination with respect to mycotoxin binding. The purpose of this study was to characterize a Tunisian clay before and after calcination (at 550 °C), and to investigate the effectiveness of the thermal treatment of this clay on its aflatoxin B1 (AFB1), G1 (AFG1), B2 (AFB2), G2 (AFG2), and zearalenone (ZEN) adsorption capacity. Firstly, the purified clay (CP) and calcined clay (CC) were characterized with X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR-IR), cation exchange capacity (CEC), specific surface area (SBET), and point of zero charge (pHPZC) measurements. Secondly, an in vitro model that simulated the pH conditions of the monogastric gastrointestinal tract was used to evaluate the binding efficiency of the tested clays when artificially mixed with aflatoxins and zearalenone. The tested clay consisted mainly of smectite and illite. Purified and calcined clay had similar chemical compositions. After heat treatment, however, some changes in the mineralogical and textural properties were observed. The calcination decreased the cation exchange capacity and the specific surface, whereas the pore size was increased. Both purified and calcined clay had a binding efficacy of over 90% for AFB1 under simulated poultry GI tract conditions. Heat treatment of the clay increased the adsorption of AFB2, AFG1, and AFG2 related to the increase in pore size of the clay by the calcination process. ZEN adsorption also increased by calcination, albeit to a more stable level at pH 3 rather than at pH 7. In conclusion, calcination of clay minerals enhanced the adsorption of aflatoxins and mostly of AFG1 and AFG2 at neutral pH of the gastrointestinal tract, and thus are associated with protection against the toxic effects of aflatoxins.

Low temperature, authigenic illite and carbonates in a mixed dolomite-clastic lagoonal and pedogenic setting, Spanish Central System, Spain

The aim of this study was to further our understanding of the pedogenic and lacustrine modification of clay minerals. Some of these modifications are of special interest because they constitute reverse weathering reactions, rare in surface environments, and because there is not yet an accurate assessment of their global relevance in mineralogical and geochemical cycles. For this study, two sections from the Central System in Spain were selected. Both are sections through the Uppper Cenomanian-Turonian mixed clastic and carbonate succession, containing both calcite and dolomite, in the Sierra de Guadarrama. Mid-Turonian sea level fall resulted in the formation of a coastal plain environment in which extensive pedogenesis occurred around saline lagoons. The mineralogical changes that have occurred as a result of sedimentation in saline lagoons and as a consequence of pedogenesis are described. Textural relationships indicate that the dolomite cement pre-dates the calcite. Silicate minerals are represented by quartz, kaolinite, illite-smectite, illite, minor plagioclase and alkali feldspar, and trace chlorite and palygorskite. There is a positive correlation between the intensity of pedogenesis and the proportion of illite in the clay assemblage in one of the sections, indicating pedogenic illitisation. In this section, the intensity of the illitisation process increases up, reaching a maximum where pedogenesis is most intense in the middle part, and then decreases as marine influence increases towards the top of the Alcorlo Formation and the overlying marine Tranquera Formation. The clay assemblages are consistent with a slow transformation process from kaolinite to illite by way of illite-smectite, taking place under surface conditions. The illitisation process has resulted in a less Fe-rich, more Mg-, and Al-rich illite than the majority of previously documented cases in the near surface. Formation of Al-rich illite is not therefore restricted to the deep subsurface.The mechanism for low temperature illitisation involves enhanced layer charge resulting from Mg2+ substitution for Al3+ (or Fe3+) and Fe3+ to Fe2+ reduction. Mg2+ enrichment may have occurred principally in saline lagoons or lakes, while Fe3+ to Fe2+ reduction occurred as a result of wetting and drying in a pedogenic environment. So far as it has been possible to establish, this dual mechanism has not previously been documented. This study indicates clearly that the dolomite and calcite are authigenic cements that precipitated in a clastic sediment, probably soon after deposition. Dolomitisation and Mg enrichment of the clay may have occurred at the same time. Seawater is the most probable source of Mg.

Design, Synthesis and Characterization of 3,4-Dihydro-2H-pyran Containing Copolymer/Clay Nanocomposites

We introduce briefly surface modification of clay minerals, structure, properties and, characterization techniques of polymer-clay (PCN's) nanocomposites. Organically modified layered-silicates or nanoclays have become an attractive class of hybrid materials due to their prospective use in a great variety of applications from industry to health. For design, synthesis and characterization for potential biomedical nanocomposites, antitumor-active copolymer; poly(DHP-alt-MA) were used to prepare copolymer/clay nanocomposites. The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized by interlamellar complex-radical copolymerization of intercalated monomer complexes of maleic anhydride (MA) and 3,4-Dihydro-2H-pyran (DHP) with three alkyl ammonium salts surface modified bentonite and monomer mixtures. Poly(DHP-alt-MA) pristine copolymer and poly(DHP-alt-MA)/organically modified bentonite nanocomposites were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), HR-Raman, X-ray diffraction (XRD) and TEM methods.

Effect of surface modification of bentonite nanoclay with polymers on its stability in an electrolyte solution

Recently surface modification of clay minerals has become increasingly important for improving the practical applications of clays and clay minerals. In this research work surface modifications of bentonite nanoclay particles were carried out by chemical grafting of different copolymers including poly(1-vinyl pyrrolidone-co-styrene) (PVP), poly(methyl methacrylate-co-methacrylic acid) (PMMA) and poly (acrylamide-co-diallyl dimethyl ammonium chloride) (PDADMAC). The efficiency of the grafting reactions was investigated using FTIR, TGA and XRD methods. It was shown that PVP as well as PDADMAC copolymers had been grafted successfully on the exterior of the nanoclay tactoids surfaces, while most of the PMMA molecules had entered the galleries and grafted on the inner surfaces of the nanoclay. Turbidimetry, zeta potentiometry and dynamic light scattering (DLS), were employed to analyze the dispersion stability of the unmodified and modified nanoclays in an electrolyte solution with high salinity. The turbidimetry results showed that stabilities of unmodified and modified nanoclay particles in the electrolyte solutions decreased as the time passed from their preparation, and after 24 h they settled completely in the solutions. However, rates of the settlement of unmodified and modified particles differed from each other, that of the modified ones being lower. This difference was attributed to the grafted copolymers on the modified particles surfaces. Also, the results of the zeta potentiometry and DLS were in harmony with the turbidimetry observations.

Electrochemical Modification of Physicochemical Soft Rock

Two mechanisms about electrochemical modification of clay minerals are summarized: one of electroosmotic dewatering and stabilization and the other of cation substitutions, structures and properties change, forming new minerals. The analyses of physicochemical soft rock (PCSR) indicate that physicochemical property of PCSR is dominated by physicochemical property of clay minerals. Therefore, it is possible to indurate PCSR in the coal-mine soft rock roadway with the electrochemical method.

Mechanism and Effect of Electrochemical Modification on Physicochemical Soft Rock

Two mechanisms about electrochemical modification of clay minerals are summarized: one of electroosmotic dewatering and stabilization and the other of cation substitutions, structures and properties change, forming new minerals. The analyses of physicochemical soft rock (PCSR) indicate that physicochemical property of PCSR is dominated by physicochemical property of clay minerals. Therefore, it is possible to indurate PCSR in the coal-mine soft rock roadway with the electrochemical method.

Interactions of pesticides with clays and layered double hydroxides: a review

AbstractThe increasing presence of pesticides in natural ecosystems has stimulated research to look for improved adsorbent materials which can be used to remediate and prevent soil and water contamination by these compounds. Among the different materials that have been assayed as adsorbents of pesticides are natural clay minerals, particularly 2:1 phyllosilicates and their structurally complementary synthetic analogues layered double hydroxides (LDHs). The great interest in natural clays and LDHs as adsorbent materials is mainly related to the large specific surface areas associated with their layered structure, the ease with which they are obtained or synthesized, and the possibility of modifying their surfaces to increase their affinity for specific adsorbates. This review summarizes the adsorptive properties of natural clays and LDHs for pesticides and related organic compounds. Particular emphasis is given to the surface modification of clay minerals and LDHs with organic ions as a strategy to improve the efficiency of these materials as pesticide adsorbents. Potential applications of unmodified and modified clays and LDHs as adsorbents to prevent and remediate soil and water contamination by pesticides are also discussed.

Structure, properties and corrosion resistivity of polymeric nanocomposite coatings based on layered silicates

This paper reviews the recent research and development of polymeric nanocomposite coatings based on layered silicates. In the past few decades, extensive research activities have been conducted on clay minerals due to their unique layered structure, rich intercalation chemistry and availability at low cost, environmental stability, and good processability. One of the most important categories of layered silicates is nanoclays. The nanoclay is considered as reinforcement for polymers in the manufacture of low-cost, lightweight and high performance nanocomposite coatings. In this paper, we try to introduce the structure, properties, and surface modification of clay minerals. Different properties of polymer clay nanocomposite coatings consisting of different polymers are also reviewed. These coatings may consist of conductive and nonconductive polymers. The corrosion resistance of each type is discussed separately. Some novel properties can be observed from the interaction of two dissimilar chemical components at the molecular level that posses enhancements in corrosion inhibition on metallic substrates. Finally, the prospective problems of industrial usage of these materials are mentioned.

Preparation of polymer/clay mineral nanocomposites via dispersion of silylated montmorillonite in a UV curable epoxy matrix

Surface modification of clay minerals plays an important role for their application as fillers for polymeric materials. Among the many modification reactions, the silanization reaction uses alkoxysilanes and exploits the OH reactive sites of the montmorillonite structure. We found that using an excess of silane it is possible to functionalize the clay mineral and, at the same time, to intercalate some monomers or oligomers into the clay mineral galleries, greatly enhancing the interlayer distance. The montmorillonite modified in this way has been then used in the preparation of nanocomposite coatings by mixing it with a photocurable epoxy matrix. After UV irradiation the coatings obtained were submitted to morphological, thermal and mechanical analysis. The photopolymerization kinetics was also investigated. The introduction of the modified montmorillonite allowed to obtain transparent nanocomposite coatings characterized by a mixed intercalated/exfoliated structure and better thermal and scratch resistance performances in comparison with the montmorillonite free coatings.

Selective Modification of Clay Minerals for the Adsorption of Herbicides Widely Used in Olive Groves

Ground and surface water contamination by herbicides applied to olive groves in Spain and other Mediterranean countries is demanding strategies to prevent and remediate the environmental problems repeatedly caused by such herbicides. In this study, six different organic cations (L-carnitine, spermine, hexadimethrine, tyramine, phenyltrimethylammonium, and hexadecyltrimethylammonium) were incorporated into Na-rich Wyoming montmorillonite (SWy-2) and Ca-rich Arizona montmorillonite (SAz-1) at two different loadings (50% and 100% of the cation exchange capacity of the clays) as a strategy to enhance the affinity of the clay minerals for three herbicides widely used in olive groves: terbuthylazine, diuron, and MCPA. The modified montmorillonites were characterized and tested as adsorbents of the herbicides through batch adsorption tests. At the experimental conditions used, some of the modified montmorillonites removed more than 95% of the herbicide initially present in aqueous solution, whereas the unmodified clays removed less than 15%. All three herbicides displayed very strong affinities for SAz-1 exchanged with hexadecyltrimethylammonium cations, particularly when these were incorporated at 100% of the cation exchange capacity of the clay mineral. Terbuthylazine and diuron also displayed very strong affinities for SWy-2 exchanged with L-carnitine and spermine, respectively. The chemical characteristics of the organic cation greatly influenced the adsorptive properties of the resultant organoclay. The herbicides were in general reversibly adsorbed by the modified clays. The results indicate that some of the tested modified clays could be suitable for the removal of the assayed herbicides from contaminated water and also as possible supports for the design of slow release formulations of such herbicides to attenuate their environmental impact when used in high-risk scenarios such as olive groves.