Fa Bergaya

• University of Orléans

A panorama of spectroscopic techniques is presented in function of the corresponding wavelengths. This chapter is an introduction to the following: (i) ten subchapters on some of these spectroscopic techniques used for clay minerals characterisation and on electron microscopy and thermal analyses, (ii) two subchapters on surface properties and ion...

Clay mineral-polymer nanocomposites were described for the first time in 1993. Since that date, they were the subject of thousands of research papers. Clay mineral-polymer nanocomposites must be carefully distinguished from microcomposites and intercalated composites. The following chapters describe polymer nanocomposites with smectites, kaolinites...

This chapter makes a general overview of pillared clay minerals. First, the general concepts of the process and the terminology recommended by the IUPAC are summarized, followed by the analysis of the host clay minerals and of the pillaring species, with special attention to the Al13 polycation, mixed species, and new species. The main experimental...

In spite of the great success of using clays and clay minerals in a large diversity of applications, an obstacle of users often is the limited knowledge in clay science. The successful future applications of clays and clay minerals strongly require a deeper understanding of the clay mineral structures and properties, that is, the structure–property...

The behaviour and uses of clays and clay minerals are often determined by the ion-exchange properties. The predominant reaction of clay minerals is cation exchange, but anion exchange reactions also have to be considered. The chapter informs on the basics of ion-exchange reactions, thermodynamics, and the sites of exchangeable cations and anions. I...

Raw clays and clay minerals are worldwide abundant but are never pure, except vermiculites or micas. This is very damaging for their applications in different areas. The presence of impurities complicates the full scientific characterization of clay minerals. Relatively simple techniques are used in industrial processing of clays (see Chapter 4.2 i...

Clays and clay minerals are recognized as the materials of the twenty-first century. Chapter 1 provides a general introduction into clay science, illustrates the classification of the clay minerals (planar and non-planar 1:1 and 2:1 clay minerals), shows the idealized formulae of some representative clay minerals, lists the current names of clays,...

Ultrafast infrared spectroscopy of the O-D stretching mode of dilute HOD in H2O probes the local environment and the hydrogen bond network of confined water. The dynamics of water molecules confined in the interlayer space of montmorillonites (Mt) and in interaction with two types of cations (Li+ and Ca2+) but also with the negatively charged silox...

This introductory chapter presents the most relevant structural, physical, and chemical properties of clay minerals for the formation of nanocomposites with polymers. The general principles of silicates classification are outlined in order to better understand the structures of the various types of clay minerals as phyllosilicates. Cation exchange...

This introductory chapter presents the most relevant structural, physical, and chemical properties of clay minerals for the formation of nanocomposites with polymers. The general principles of silicates classification are outlined in order to better understand the structures of the various types of clay minerals as phyllosilicates. Cation exchange...

What's in a NameMultiscale Organization of Clay MineralsIntimate Organization of the LayerMost Relevant Physicochemical Properties of Clay MineralAvailability of Natural Clays and Synthetic Clay MineralsClays and (Modified) Clay Minerals as FillersAcknowledgmentReferences

This chapter makes a general overview of pillared clay minerals. First, the general concepts of the process and the terminology recommended by the IUPAC are summarized, followed by the analysis of the host clay minerals and of the pillaring species, with special attention to the Al13 polycation, mixed species, and new species. The main experimental...

This chapter examines the use of industrial clay minerals as nanomaterials. In the first part, clay minerals are introduced and a survey is given of those properties which are relevant for clay-polymer nanocomposites (CPN). These properties are: morphology of the clay-mineral particles, sizes and shapes of the layers, cation exchange, and hydrophil...

This volume covers the topics related to the 13th EMU School ‘Layered Mineral Structures and their Application in Advanced Technologies’. All of the selected topics, the school, and this volume are thus aimed at providing an in-depth knowledge of the complex field of layered materials, with an attempt to address several fundamental aspects, which r...

In recent years, immense interest has been paid to biomolecular architecture with the aim of protein assembly in two dimensions on solid substrates, and the construction of clay–protein ultrathin films (CPUFs). An overview is provided of recent research on hybrid ultrafilms or nanofilms of clay mineral layers and protein molecules. Two techniques,...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

As is well established in these reviews, CPN research is a complex subject that is both timely and developing rapidly. While the term “polymer-clay nanocomposite” is more conventional in the literature, the term CPN is employed in this volume in order to stress the importance of the clay science. The number of publications on CPN has increased expo...

This chapter gives a brief survey of cation and anion exchange with particular reference to the definition and determination of the cation exchange capacity (CEC) of clay minerals. Ion exchange is of fundamental and practical importance to soil studies and all fields in which clay materials feature. The ability of colloidal particles (including cla...

Publisher Summary This chapter describes synthetic clay minerals and purification of natural clays. A complete purification cycle is time consuming. However, not all the purification steps are always necessary; steps can be omitted depending on the purpose of the investigation. In contrast to soil clays, clays from geological deposits (such as bent...

This chapter attracts the attention of clay scientists in academe and industry as well as in politics (as research needs funding), and focuses on the importance of clay science to society and the quality of life. The economic benefits seem evident because clays are abundant, widespread, and inexpensive compared with other raw materials. The chapter...

This chapter discusses the physical and chemical modification of clays and clay minerals in the broad sense. The surface properties and reactivity of clay minerals may also be modified by adsorption and intercalation of small and polymeric organic species.

This chapter discusses clays and its affect on environment and health. Because of their large propensity for adsorbing and immobilizing extraneous species, clays and clay minerals can serve as materials for pollution control, carriers of pesticides, and liners in waste disposal and barriers in nuclear waste management. The peculiar surface properti...

This chapter concerns the industrial applications of clays in general. The versatility of clay minerals is also reflected by their usage in the formation and preparation of clay–polymer nanocomposites.

This chapter critically assesses some analytical techniques, such as X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, small-angle scattering techniques, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and transmission electron microscopy. The results of spectroscopic analyses, however, have to be in...

This chapter describes the layered double hydroxides (LDH) called “anionic clays” and three-dimensional zeolites that share several common properties with two-dimensional phyllosilicates. The chapter discusses hydrated cement phases that benefit from the knowledge of clay mineral properties.

This chapter presents history of clay science. Clays were known and used since antiquity but yet remain essential to the synthesis and development of modern materials, such as clay-polymer nanocomposites. However, clay science is a relatively young discipline, having begun only about a century ago. Many factors contribute to the rapid development o...

Clay science is an extraordinarily complex, heterogeneous, and multifaceted discipline, because the clay mineral properties are very complex and are dependent on environmental conditions. The techniques for characterization of clay minerals are very delicate, because of fine grain-size of clay materials. Analyses are made even more difficult becaus...

The determination of the cation exchange capacity (CEC) of clays by exchange with the cationic copper complexes [Cu(en)2]2+ and [Cu(trien)]2+ is revisited. The procedures reported by Bergaya & Vayer (1997) and Meier & Kahr (1999) are modified slightly. The concentration of the copper complexes in the equilibrium solutions is measured by spectral ph...

A novel method of preparing Al-pillared montmorillonite has been developed. The process uses a minimum amount of liquid and is simpler to operate than the conventional method of pillaring. Here, the pillaring agent (solid Al13 nitrate) is ground together with the powdered raw montmorillonite (from Wyoming) and dialysed against a limited volume of d...

New clay fillers are mixed with linear low-density polyethylene at 160C for 10min to obtain clay-PE nanocomposites (CLAYPEN) by melt intercalation. Raw montmorillonite (Mt) was pillared (PMt) with partially hydrolyzed Al and Fe salt solutions and further reacted with hexadecyl trimethylammonium bromide (OPMt). For comparison, the hexadecyl trimethy...

The effect of pH on the static filtration properties of purified sodium montmorillonite dispersions depends on the applied pressure. At 1.5 × 105 Pa, the double-layer repulsion resists the applied pressure at natural pH, which is close to neutral pH, and at basic pH. At acidic pH, where the cake is the thinnest and the least permeable, the edge-to-...

The effect of clay content on the static filtration properties of purified Na-montmorillonite suspensions was studied at two different pressures. The results of filtering parameters are as expected. When the clay percentage increases, the thickness (e) of the obtained cake increases, leading to the decrease of water loss (WL), and consequently, to...

The current research in herbicide application aims to develop formulations that reduce leaching of the herbicide to deep layers of the soil and to concentrate its biological activity at the top layers. Adsorption of metolachlor on clay minerals, their organic derivatives or pillared forms provides the best possibility to develop slow-release formul...

Changes in particle organization and pore-spaces with applied mechanical and hydraulic stresses were followed using TEM, SAXS mercury porosimetry and gas adsorption for two Na-smectites, Laponite and hectorite, with similar structural formulae but different particle sizes. The TEM images show that hectorite has particles larger and more anisotropic...

The localization and number of the different types of water in two Na-smectites (Laponite and hectorite) were studied as a function of the hydromechanical stresses applied. Water volume variation was obtained by macroscopic oedometric tests. Thermogravimetric analysis (TGA), X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) were used to...

The effect of pH on the rheological behavior of three purified sodium bentonite (HP, GP, and WP) suspensions is studied. Each clay is studied as a function of pH, at a chosen constant concentration. These concentrations correspond to the lower concentrations at which the yield stress can be detected. They are 12.5, 8.5, and 5.5% w/w, respectively,...

The adsorption of the cationic surfactant BDDAC on a hydrophilic smectite (montmorillonite) surface has been investigated, especially in the range of low coverage ratios where surfactant ions are adsorbed through cation-exchange with the counterions of the clay. The surfactant coions (Cl(-)) were found to be adsorbed simultaneously with the cationi...

This paper summarizes the findings from an experimental program concerning the hydromechanical behavior of two smectite clays tested under high stresses. Increasing axial stress on the smectite samples under controlled relative humidity (suction) leads to collapse in the soil structure and increases the degree of saturation. Irreversible volume cha...

Various processes can be used for the treatment of wastewater, but the one we feel to be important and more promising is the wet peroxide oxidation (WPO), in the presence of a solid catalyst, at atmospheric pressure and at room temperature. Different types of materials can be used as catalysts for such reactions, but as shown in previous studies de...

Various processes can be used for the treatment of wastewater, but the one we feel to be important and more promising is the wet peroxide oxidation (WPO), in the presence of a solid catalyst, at atmospheric pressure and at room temperature. Different types of materials can be used as catalysts for such reactions, but as shown in previous studies de...

Modification of smectite by highly charged inorganic polycations gives a type of materials called Pillared Clays (PILCS). These materials are also potential candidates for sorbents of compounds of agricultural interest , or of pollutants molecules in wastewater treatment. Modified PILCS by the cationic surfactant (BTDDMAC) or by its polar head, the...

Raw montmorillonites treated with mixed Al–Fe pillaring solutions, with Fe/(Al + Fe) molar ratio between 0.1 and 1, and heated at 300 °C lead to large d-spacings according to XRD which increase from 52 Å for the sample with the lowest iron content to 76 Å for the pure Fe-treated clay sample.

Although the kinetics of the dehydroxylation of kaolinite have been widely studied, there is no definitive explanation of its mechanism due to its dependence on a variety of parameters. In this study, the dehydroxylation of kaolinite has been studied using controlled-transformation rate thermal analysis (CRTA), allowing precise control of the react...

New mixed (AlCu)-pillared clays are prepared from a crude bentonite sample (H) (Tunisia deposit) by two discrete procedures: (a) a classical ‘D’ method by which Al or (Al, Cu) nitrate solutions, hydrolyzed with NaOH, are added to a 2% clay suspension and (b) a ‘P’ method where the clay powder is directly dispersed in the pillaring solution. Interca...

29Si Nuclear Magnetic Resonance was used to analyse silicate polymerization in relation with the kinetic control of the curing process. Controlled Rate Thermal Analysis (CRTA) was applied to the monitoring of the thermal curing of a Reactive Powder Concrete. Heating could be adjusted so as to keep the rate of gas evolution constant and in dynamic e...

Three crude bentonites samples from USA (W), Tunisia (H) and Algeria (MR) have been used in order to prepare Cu-exchanged and new mixed AlCu pillared clays by three methods (i) a classical ‘dilute suspension and solution’ method by adding the nitrate pillaring solution to a 2% clay suspension, (ii) a ‘powder in solution’ method where the clay powd...

A method for the rapid determination of CEC values in clays using au ethylenediamine complex of Cu was tested with different clays. The single-step procedure is fast and does not require sophisticated apparatus. The exchange with most cations—and even with those of heavy metals—is irreversible and can be carried out over a range of pH values. The r...

Controlled rate thermal analysis (CRTA) was applied to the thermal curing of a reactive powder concrete. Heating was adjusted to keep the rate of gas evolution constant and in dynamic equilibrium at a pressure of 3 Pa. In this way, all internal gradients were kept constant and homogeneous samples were produced. Six different solid-state transformat...

This paper presents preliminary results on the fixation of Zn2+ and Pb2+ by a purified Wyoming Ca-montmorillonite, in different experimental conditions: variable (3 · 10−5 < I < 3 · 10−2M or constant (I = 3.10−2 M) low ionic strength solution, and high (I = 3 M) ionic strength solutions at 20°C and 50°C. In low ionic strength solutions, the fixatio...

The gelation process of industrial organo-bentone in organic solvents is a complex phenomenon due to various parameters, such as, the crystallographic nature of the clay, the nature of adsorbed surfactant, the dielectric constant of medium. Sol-gel phase diagrams have been established by varying the dielectric constant versus solid-liquid ratio of...

The great importance of problems related to the storage of chemical and radioactive wastes requires better understanding of the behaviour of the host media. In the case of clay soils, their behaviour is controlled by their microtexture, their mineral composition and their physico-chemical properties (interaction between interstitial fluid and solid...

The dehydroxylation of kaolinite leading to metakaolinite was studied by transmission electron microscopy. TEM techniques allow the study of morphology, structure (by selected-area electron diffraction) and lattice imaging (by high resolution) in a non-destructive way. The samples were prepared using a controlled-rate thermal analysis method which...

Pillared clays (PC) generally present textural complexity, geometrical constraints and possible chemical heterogeneity by pillaring. As far as surface area and porosity measurements by physical adsorption of nitrogen are concerned, this overall complexity introduces interpretation difficulties. We consider two aspects of this problem in pillared cl...

Infrared spectroscopy is used to distinguish between octahedral and tetrahedral substitutions in an interstratified illite-smectite clay. The Hofmann-Klemen (Li) test suggests that the AlMg square and FeMg square octahedral vacancies are preferentially occupied by Li after thermal treatment at 250-degrees-C. The ammonium (Chourabi-Fripiat) test rev...

The photosensitized cleavage of water is hampered by fast recombination of usually charged intermediates. Charged surfaces carrying the appropriate catalyst for both the oxidation and reduction of the substrate might be used to compete with this recombination. In this study negatively charged clay minerals and positively charged Al(OH)x gels were e...

The pillaring of a Laponite by alumina pillars, iron pillars and mixed AI-Fe pillars was obtained by a simple in situ method starting from A1CI3 and/or FeCI 3 solutions with different molar ratio Fe/(Fe + AI), and from NaOH solution added simultaneously to the clay suspension. The All 3 pillars were evidenced by XRD and NMR spectra. The density and...

We discuss the problems raised by chemical heterogeneity and geometrical confinement in pillared clays for the measure of their surface area and their porosity by physical adsorption.

The pillaring of a Laponite by alumina pillars, iron pillars and mixed Al-Fe pillars was obtained by a simple in situ method starting from AlCl3 and/or FeCl3 solutions with different molar ratio Fe/(Fe + Al), and from NaOH solution added simultaneously to the clay suspension. The Fe pillars are larger than Al13 pillars and slowly reducible by hydro...

The catalytic properties of a synthetic hectorite (laponite) pillared with mixed Al and Fe oxide are studied for syngas conversion. The results show two different behaviors depending on the ratio Fe/(Al + Fe) of the catalysts. Al-Fe pillars in alumina-rich samples are particularly active and selective to light olefins. The iron pillars in iron-rich...

Two smectite clays (montmorillonite and hectorite) were utilized for the preparation of silicon oxynitride ceramic powders. Because of their high temperature properties, the nitride ceramics are major candidates for use in ceramic gas turbines and other high performance applications. The synthesis of ceramic powders was investigated by firing mixtu...

The preparation of -SiMONs by the thermal treatment (1373–1773 K) under nitrogen of various mixtures of clays and organic molecules (acrylonitrile) or carbon (charcoal) or graphitic oxide, was investigated. Cation (Na+, Y3+, C6-amine+) exchanged smectites (montmorillonite or hectorite) and kaolinite were used. With charcoal mixtures, a threshold of...

Mixed Al-Fe pillars were obtained by a simple method of preparation of PCL (Pillared Clay Laponite). Solutions of AlCl3, FeCl3 and NaOH were mixed with a clay suspension in adequate concentrations and kinetic conditions. A combination of techniques (chemical analysis, XRD, NMR and H2TPR) shows iron cations replace a few octahedral Al in the Al13 pi...

The adsorption of acrylonitrile (AN) monomer vapour in the interlamellar space of smectitcs exchanged with different cations (Na or Y or hexylammonium) was monitored and used to yield macromolecular layers. Polymerization in the presence or absence of a free-radical initiator was obtained by heating at 100-degrees-C for 72 h. Cyclization can alread...

The decolorisation of rape-seed oils by a recently discovered Tunisian bentonite was tested. It is proved that this clay has a valuable high decolorizing power after appropriate activation by acids.We have tried to relate the adsorption of a model colored molecule (β-carotene) with the modified surface properties of the activated clay, such as surf...

We describe the preparation and the microtexture of three classes of precursors for the synthesis of ceramic powders or films of the SiMON family (M=Al, Mg, Y). (i) simple mechanical mixtures of a non-swelling clay of the kaolinite family with charcoal, in which the two phases are separated at micronic or slightly submicronic level. The interface a...

Stable, active and shape selective catalysts for the transformation of syngas into light hydrocarbons (C2—C3 alkenes) have been prepared by ion exchanging a laponite with mixed polyhydroxycations of Fe and Al; these results clearly show that mixed AlFexOy species are active and selective sites for syngas conversion.

Les argiles, les zeolithes et d'autres solides microporeux tels que les silices permettent de faire des reactions chimiques dans des espaces a geometrie restreinte. Dans les argiles du groupe des smectites et des vermiculites, cet espace est quasi-bidimensionnel. Dans les zeolithes, la dimensionnalite effective de l'espace reactionnel a l'echelle m...

We have simulated the adsorption of homologous series of ‘‘molecules’’ on deterministic fractal curves in the whole range 1≤D

Clay Minerals can be used in photocatalysis (i) to support heterogeneous redox catalysts, including metals, oxides and sulphides (ii) to anchor, by covalent linkage, homogeneous redox catalysts, and (iii) to intercalate photocatalytic transition metal complexes. The photocatalytic reaction can be performed either at the solid-solution interface in...

An example is given of the interaction of chemical analysis, XRD and IR spectroscopy for determination of clay mineralogical composition of three fine-grained fractions, and also characterization of individual species. -D.J.M.

The visible light irradiation of a mixed colloidal system prepared from sepiolite—Ru(bpy)32+RuO2 (bpy  2,2′-bipyridine) composite particles and AlxEu1−x(OH)3 gels leads to the oscillatory evolution of hydrogen and oxygen. With respect to the previously reported results obtained with AlxEu1−x(OH)3Pt, the following differences were obtained: (i) t...

A corrensite from Taro Valley, Italy, was studied by infrared analysis at different temperatures in the natural state and after exchange with seven different cations. The vibrational bands in the OH-stretching region can be divided into three main absorption regions: 3690-3640, 3580-3560, and 3500-3000 cm ⁻¹ . The influence of the cation hydration...

For most users, clays are just a class of mineral materials characterized by various properties such as a very small particle size, a strong adsorption capacity, a soft touch, or a plastic behavior when wetted. For geologists and soil scientists, clays are commonly defined as the fine fraction of rocks and soils, with an upper limit for the particl...