Academic literature on the topic 'Beidellite'

AbstractSmectites in the montmorillonite-beidellite pseudo-binary system were synthesized from glass at the hydrothermal conditions 100 MPa and 250–500°C. Products were analysed by X-ray powder diffraction for randomly oriented and glycolated samples, and also according to the Greene-Kelly test. A new mixed-layer mineral consisting of regularly interstratified montmorillonite-beidellite was found below 400°C for M50B50 composition, where M and B denote the compositions of ideal Na-montmorillonite and Na-beidellite, respectively. Montmorillonite was obtained as a single phase below 375°C in the composition range from M100B0 to M78B22. Above 375°C, montmorillonite decomposed into an assemblage of beidellite, saponite and a silica mineral. Beidellite as a single phase was synthesized below 400°C for M0B100 composition. Above 450°C, Na-rectorite (regularly interstratified paragonite-beidellite), Mg-free dioctahedral smectite and/or Mg-rich trioctahedral smectite appeared together with silica minerals. These smectites showed the same swelling behaviour as that of montmorillonite. Phase relations in the montmorillonite-beidellite pseudo-binary system indicate no complete solid-solution series.

AbstractThe adsorption of the metachromic dye acridine orange (AO) by Na-beidellite was investigated by visible spectroscopy. Different types of clay-AO association were identified from the appearance and location of absorption bands α or β. The colloidal properties were determined from curves of the absorbance vs. the degree of saturation. Three regions were identified in the absorbance curve. In the first region beidellite is peptized with small amounts of AO and the dye penetrates into the interlayer space where it undergoes metachromasy due to π interactions between the aromatic entity and the oxygen plane of the clay. With larger amounts of AO (second region), the clay flocculates due to the aggregation of the dye cations in the interparticle space of the flocs. In excess AO (third region), beidellite is gradually peptized, forming small tactoids with monomeric AO in the interlayer space and at the same time adsorbing dimeric and polymeric AO cationic species at the solid-liquid interface. Compared with the other smectites, AO shows the greatest tendency to undergo metachromasy in the presence of beidellite.

Abstract Beidellite clay mineral after intercalation of OH-Cr(III) species were thermally analyzed up to 1350 °C in oxygen and nitrogen atmospheres. OH-Cr-beidellite can be used as a pillared clay precursor for catalysis or as adsorbent applications. However, in this paper beidellite enriched in chromium were analyzed at different thermal treatments up to high temperature for evaluating structural changes for possible future ceramic applications. The structural changes were followed by thermal analysis and X-ray diffraction. The thermal treatment of OH-Cr-beidellite in oxygen and nitrogen atmospheres developed different mineralogical phases up to 1050 °C, but at higher temperatures, the same phases were developed in both atmosphere treatments. Eskolaite phase (Cr2O3) appeared in the sample after heating at 400 °C in oxygen atmosphere, whereas grimaldite (CrO-OH) in nitrogen atmosphere, maintaining the starting phases. At 1000 °C the raw clay minerals disappeared, as it is knew. At 1050 °C in nitrogen atmosphere, grimaldite was absent and eskolaite appeared. At 1350 °C in the samples calcined in both atmospheres, quartz, cristobalite and mullite as the main phases and in lower contents aluminum oxide and aluminum-chromium oxide [(Al,Cr)2O3] were present.

AbstractThe Ga for A1 substitution in kaolinites and smectites was studied using clay synthesis from initial gels having an (Al + Ga)/Si ratio of kaolinites andMGa = Ga/(Ga + A1) ratio ranging from 0 to 1. Only kaolinite was obtained for MGa in the range 0-0.10. For higher MGa, synthesized clays were both kaolinite and beidellite, or pure beidellites. The evolution of b cell parameters, and the appearance of avAI-OH-Ga absorption band at 3600 cm-1in FFIR spectra, proves the progressive substitution of AI by Ga in kaolinite. The low substitution of AI by Ga in kaolinite can be correlated with the large difference in ionic radii between Al3+and Ga3+which causes a large increase in cell dimensions. By contrast, the incorporation of Ga in smectites is easy and can be complete.

Ce travail a été consacré au développement de nouveaux microréservoirs d'inhibiteurs de corrosion à base de ressources naturelles minérales (les argiles marocaines de types beidellite et palygorskite), et organiques (le chitosane et l'acide heptanoïque) pour être utilisés en tant que charges anticorrosion dans les peintures. Dans les réservoirs de type beidellite, le stockage des inhibiteurs de corrosion a été réalisé soit en saturant les espaces interfoliaires par des cations inhibiteurs de corrosion tels que Ca2+ ou Ce3+, soit en modifiant les charges des feuillets argileux par intercalation du biopolymère chitosane afin d'adsorber des composés anioniques comme les ions heptanoate (C7-). Dans les réservoirs de type palygorskite, le stockage est basé sur le greffage d'un alkoxysilane sur les sites silanols de surface permettant d'adsorber les composés inhibiteurs via des sites NH3+. Après avoir caractérisé les matériaux avant et après fonctionnalisation par différentes techniques analytiques, les performances d'inhibition de corrosion du zinc et d'un acier doux en milieu NaCl ont été évaluées et comparées à celles du composé commercial dihydrogénotriphosphate d'aluminium (TPA) en utilisant des techniques électrochimiques stationnaires et dynamiques. Globalement, le revêtement organique à base de la beidellite modifiée au C7- montre une meilleure protection de l'acier électrozingué que le revêtement au TPA. De même, le revêtement organique comportant la palygorskite greffée au C-7 présente une performance d'inhibition de la corrosion de l'acier doux très intéressante par rapport au revêtement au TPA, sur environ 400 h d'immersion<br>This work was devoted to the development of new micrometric tanks of corrosion inhibitors based on mineral natural resources (Moroccan beidellite and palygorskite clays), and organic (chitosan and heptanoic acid) to be used as corrosion inhibitor tanks in the paintings. In the reservoirs of beidellite type, the storage of corrosion inhibitors made either by saturating the interlamellar areas by corrosion inhibitors cations such as Ca2+, or Ce3+, or by modifying the electrostatic charge of clays by intercalation of chitosan biopolymer in order to adsorb anionic compounds as heptanoate ions (C7-. In palygorskite type tanks, storage is based on the grafting of an alkoxysilane on the surface silanol sites to adsorb compounds via NH3+ sites. After characterizing materials before and after functionalization by several analytical techniques, the performance of corrosion inhibitors on zinc and mild steel in NaCl medium was evaluated and compared to those of commercial compound aluminium dihydrogen triphosphate (TPA) using stationary and dynamic electrochemical techniques. Overall, the organic coating containing modified C7- beidellite shows better protection of zinc than TPA compound. Similarly, C7- grafted palygorskite coating presents a very interesting performance of corrosion inhibition of mild steel corrosion compared to the coating with TPA, during approximately 400 h of immersion

Les smectites sont présentent dans de nombreux environnements de surface et sub-surface au sein desquels elles jouent un rôle prépondérant dans la mobilité des cations majeurs et traces de part leurs capacités d’adsorption. En contexte de réhabilitation de sites miniers exploités par lixiviation acide, ces smectites jouent un rôle dans la remontée du pH des eaux ainsi que dans l’immobilisation des éléments solubilisés. La nature des argiles présentent dans les sables non consolidés d’un aquifère exploité a donc été étudié. La présence de smectites du type beidellite (charge tétraédrique) a été mise en évidence. Cependant, il existe peu d’études sur les propriétés de la beidellite, la majorité portant sur la montmorillonite (charge octaédrique). Un modèle d’échange pour 5 cations majeurs des eaux naturelles (Na, K, Ca, Mg, H) et un élément trace (226Ra) a donc été réalisé sur une beidellite de référence. Les vitesses de dissolution et les mécanismes à l’interface solide/solution en milieu acide ont ensuite été étudiés, validant l’application du modèle d’échange à bas pH. Des effets dus à l’organisation des particules en suspension (texture/agrégation) ont aussi été mis en évidence sur les propriétés d’échange et de dissolution. Lors de ces travaux, l’accent a été mis sur l’impact de la cristallochimie sur la réactivité des smectites par comparaison entre les propriétés de la beidellite et de la montmorillonite. Les résultats indiquent que la cristallochimie des smectites a un impact significatif sur leur comportement, ce paramètre pourrait ainsi être utilisé afin d’alimenter les modèles de transport réactif prenant en compte les propriétés des smectites<br>Swelling clay minerals, in particular smectites, are present in many surface and subsurface environments in which they have a major impact on the mobility of major cations and trace elements due to their adsorption capacity. In context of remediation of mining environments operated by acid leaching, these smectites can act as pH buffer and play a role in the immobilization of soluble elements. The type of clay minerals present in the poorly consolidated sands of an aquifer leached by acid solutions was studied. The presence of beidellite type smectites (di-octahedral, tetrahedral charge) was evidenced. However, few studies exist on the ion exchange properties or the dissolution of beidellite, as most of them deal with montmorillonite properties (di-octahedral, octahedral charge). Then, an ion-exchange model involving 5 major cations of natural waters (Na, K, Ca, Mg, H) and one trace element (226Ra) was proposed for a reference beidellite. Dissolution rates and interfacial mechanisms in acidic solutions were investigated in order to check for the validity the ion-exchange model at low pH. Moreover, effects due to the texture/aggregation of particles in suspension were evidenced on the ion-exchange and dissolution properties. This study was focused on the impact of the crystal chemistry on reactive property of the smectites, by comparison of the properties of beidellite with those of montmorillonitic minerals. Results indicate that smectites crystal chemistry has a significant impact on their properties, and such parameter could be considered in reactive transport models when they take into account cation exchange and dissolution properties of smectites

Des films composites et nanocomposites ont été élaborés par la méthode du casting à partir d’amidon natif de manioc. Ils ont été plastifiés par le glycérol et renforcés par des chargesminérales synthétiques de zéolithe Beta et de beidellite sodique. L’influence du type de charge, de l’état de la charge (lyophilisé ou non-lyophilisé ou séchage à l’air) ainsi que du taux de charge sur les propriétés mécaniques et barrières à la vapeur d’eau des films correspondants a été étudiée. Les valeurs de la solubilité dans l’eau et de la perméabilité à la vapeur d’eau des échantillons renforcés par des nanocristaux de zéolithe Beta lyophilisés sont plus grandes que celles du film de contrôle. Une augmentation significative des propriétés mécaniques, en particulier le module d’Young de ces films a aussi été observée. Une amélioration de la perméabilité à la vapeur d’eau des films composites contenant des cristaux de beidellite sodique et des films nanocomposites contenant des nanocristaux de zéolithe Beta a été trouvée. Tous les films ont été caractérisés par diffraction de rayons X<br>Composite and nanocomposite films were prepared by casting method, using native cassava starch. The films were plasticized with glycerol and reinforced with synthetic Beta zeolite nanocrystals and Na-beidellite crystals. We studied the effect of the filler contents and type on the mechanical and water barrier properties of the resulting films. We found that filmsreinforced with lyophilized Beta zeolite nanocrystals present both high water solubility (WS) and high water vapor permeability (WVP) values compared to those of the pristine film. A drastic increase of the mechanical properties, especially in the Young’s modulus, of these films was also observed. An improvement of the WVP was found for composites prepared from Na-beidellite crystals and for nanocomposites from non-lyophilized Beta zeolite nanocrystals. All the films were characterized by X-ray diffraction

Ce travail est consacré à l'élaboration par voie humide (pontage, solvothermale et colloïdale) de photocatalyseur TiO2 supporté sur trois types de minéraux argileux d'origine marocaine: la stévensite, la beidellite et la palygorskite, à leurs caractérisations et finalement à l'évaluation de leurs activités photocatalytiques vis-à-vis de l'élimination en milieu aqueux du colorant anionique l'Orange G (OG) très utilisé en industrie textile. La stévensite et la beidellite sont toutes les deux des smectites de types magnésien trioctaédrique et aluminifère dioctaédrique respectivement. En revanche, la palygorskite est un minéral fibreux riche en Al doté d'un caractère dioctaédrique très marqué. Les matériaux photocatalyseurs supportés développés par le pontage de la stévensite ou de la beidellite ne révèlent pas de formation de piliers interlamellaires de TiO2, mais plutôt l'obtention dans les deux cas de matrice de TiO2 amorphe dans laquelle sont éparpillées quelques rares particules indemnes de phyllosilicates. De même, ceux à base de stévensite élaborés par la méthode solvothermale révèlent des particules du phyllosilicate désintégrées au sein d'une matrice de TiO2 toutefois cristallisée sous forme d'anatase. Néanmoins, la fonctionnalisation selon la voie colloïdale a permis d'immobiliser avec succès des nanoparticules d'anatase (10 nm) sur aussi bien des feuillets plus ou moins exfoliés de stévensite ou de beidellite que sur des fibres de palygorskite. L'anatase attachée aux particules de ces minéraux argileux demeure extraordinairement stable jusqu'à 900 °C alors que celle formée en absence de ces phyllosilicates se convertit complètement en rutile vers 650 °C. Cette stabilité remarquable de l'anatase supportée est due à l'empêchement de la croissance, par coalescence à haute température, de la taille de ses particules au-delà de la taille critique (30 nm) requise pour sa conversion en rutile relativement moins photoactive. Les essais de photocatalyse révèlent que l'activité catalytique des différents matériaux élaborés croit selon la méthode de fonctionnalisation: pontage - méthode solvothermale - voie colloïdale et aussi selon la nature du minéral argileux : stévensite - beidellite - palygorskite. En outre, les matériaux photocatalyseurs supportés, à base de beidellite ou de palygorskite, développés par la voie colloïdale, manifestent une activité deux fois supérieure à celle de la poudre commerciale TiO2 Degussa P25. Leurs particules floculent aisément, ce qui facilite leur élimination du milieu aqueux sans recourir à la microfilitration requise dans le cas de la Degussa P25<br>This work was devoted to the elaboration by wet route (pillaring, solvothermal and colloidal) of TiO2 supported photocatalysts on three kinds of clay minerals (stevensite, beidellite and palygorskite) from Morocco, to their characterizations and finally to the evaluation of their photocatalytic activities towards the removal from aqueous media of anionic Orange G dye, widely used in textile industry. Stevensite and beidellite were magnesian trioctahedral and aluminiferous dioctahedral smectites respectively. Nevertheless, palygorskite was a fibrous Al-rich clay mineral with a predominant dioctahedral character. The photocatalyst materials elaborated by the pillaring of stevensite or beidellite did not reveal the formation of TiO2 interlayer pillars, but the observation of an amorphous matrix of Ti-rich phase within which were distributed some rare unaltered particles of phyllosilicates. Those based on stevensite elaborated according to solvothermal method also showed dissolved phyllosilicates particles, but within crystalline TiO2 anatase matrix. Nevertheless, the functionalized materials developed according to colloidal route exhibited successful immobilization of anatase nanoparticles (10 nm) onto as well as more or less exfoliated layers of stevensite or beidellite than on palygorskite fibers. Anatase remained remarkably stable up to 900 °C when attached to particles of clay minerals in comparison with that developed in their absence which underwent a complete transformation into rutile at around 650°C. This remarkable stability at high temperature of anatase supported on clay minerals particles was due to the hindrance of particles growth by sintering whose the sizes remained below the nucleus critical sizes (30 nm) required for its transition into less photoactive rutile. The photocatalysis tests revealed that the catalytic activity of different elaborated materials increased according to the synthesis route: pillaring process - solvothermal method - colloidal route and according to the nature of clay mineral: stevensite - beidellite - palygorskite. In addition, the supported photocatalysts based on beidellite or palygorskite prepared by colloidal route were found to be twice more active than the commercial TiO2 powder Degussa P25. Furthermore, their particles easily floculated so that they are readily removable from treated solutions without resorting to expensive microfiltration required upon the use of Degussa P25

Estudos sobre a inserção de complexos oxindolimínicos de cobre(II) ou zinco(II) em argilas sintéticas beidelitas foram desenvolvidos visando obter carregadores inorgânicos capazes de promover a liberação modificada de metalofármacos. Investigações anteriores mostraram que os complexos estudados são promissores agentes antitumorais. São capazes de se ligar ao DNA, nas alças menor ou maior dependendo do ligante, causando danos oxidativos através da formação de espécies reativas de oxigênio (EROs), especialmente radicais hidroxil, no caso de complexos de cobre, que apresentam atividade redox. Também interagem com mitocôndrias levando a uma diminuição do potencial de membrana e atuando como agentes desacopladores. Constituem assim compostos indutores de apoptose ou morte celular programada. Adicionalmente inibem proteínas envolvidas no ciclo celular, como topoisomerase I humana e quinases dependentes de ciclina (CDK1 e CDK2). As beidelitas foram sintetizadas e caracterizadas por métodos já descritos na literatura. Posteriormente, em presença dos complexos, formaram materiais híbridos do tipo beidellita/[complexo]. A caracterização das argilas e dos materiais híbridos obtidos foi realizada usando diferentes técnicas: espectroscopias UV/Vis, IV e EPR, análise termogravimétrica, difratometria de raios X. Na caracterização dos complexos utilizou-se ainda espectrometria de massas (ESI-MS). Os materiais híbridos preparados mostraram-se estáveis e capazes de inviabilizar células tumorais (HeLa), no caso dos materiais híbridos com compostos de cobre(II), com IC50 na faixa de 0,11 a 0,41 mg/mL. Ao contrário, os compostos análogos de zinco(II) e as argilas puras mostraram-se não-tóxicas frente às mesmas células. Os resultados obtidos indicam uma promissora possibilidade de uso das beidellitas como carregadores destes complexos metálicos.<br>Studies on the insertion of oxindolimine complexes of copper(II) or zinc(II) in synthetic beidellites clays have been developed to obtain an inorganic support capable of promoting the modified-release of metallopharmaceuticals. Previous investigations have shown that the studied complexes are promising antitumor agents. They are able to bind to DNA, in the minor or major groves, causing oxidative damage via formation of reactive oxygen species (ROS), especially hydroxyl radicals, in the case of copper complexes, which have redox properties. They also interact with mitochondria leading to a decrease of membrane potential and acting as decoupling agent. Thus, these compounds can induce apoptosis or programmed cell death. Additionally, they inhibit proteins involved in the cell cycle, such as human topoisomerase I and cyclin dependent kinases (CDK1 and CDK2). The beidellites were synthesized and characterized by methods described in the literature. Additionally, in the presence of these complexes were obtained hybrid materials type beidellita/[complex]. The characterization of clays and the obtained hybrid materials were performed using different techniques: spectroscopy UV/Vis, IR and EPR, thermogravimetric analysis, X-ray powder diffraction. In the characterization of the complexes mass spectrometry (ESI-MS) was also used. The prepared hybrid materials were stable and able to derail tumor cells (HeLa) in the case of hybrid materials with copper(II) compounds, with IC50 in the range from 0.11 to 0.41 mg/mL. Unlikely, the analogous compounds of zinc(II) and pure clays have proved to be non-toxic facing the same cells. These results indicate a promising possibility of using the beidellites as carriers of these antitumor metal complexes