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M.s. Karmous - One of the best experts on this subject based on the ideXlab platform.
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charge location effect on the hydration properties of synthetic saponite and Hectorite saturated by na ca2 cations xrd investigation
Applied Clay Science, 2009Co-Authors: M.s. Karmous, Jeanlouis Robert, Bruno Lanson, Ben H Rhaiem, Ben Haj A AmaraAbstract:This paper aims at comparing the effect of charge location on the hydration properties of two trioctahedral synthetic minerals: saponite and Hectorite. The samples were characterised by a layer charge of 0.4 charge per half unit cell and were saturated with Na+ or Ca2+. The hydration behaviour was studied by determining the structural characteristics which were obtained by modelling XRD patterns. XRD patterns were recorded under controlled relative humidity (RH). The hydrated states of Ca-Hectorite were more homogeneous than those of saponite whereas the transition from 1W to 2W occurred at lower RH rates for saponite than for Hectorite. For heterogeneous samples, the 1W and 2W layers were stacked randomly fashion for Hectorite. Na-saponite-0.4 and Ca-saponite-0.4 were made up of types of layer; one water layer (1W) and two-water layers (2W). The stacking of these layers showed some segregation.
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Charge location effect on the hydration properties of synthetic saponite and Hectorite saturated by Na+, Ca2+ cations: XRD investigation
Applied Clay Science, 2009Co-Authors: M.s. Karmous, Jeanlouis Robert, Hafsia Ben Rhaiem, Bruno Lanson, Abdesselem Ben Haj AmaraAbstract:This paper aims at comparing the effect of charge location on the hydration properties of two trioctahedral synthetic minerals: saponite and Hectorite. The samples were characterised by a layer charge of 0.4 charge per half unit cell and were saturated with Na+ or Ca2+. The hydration behaviour was studied by determining the structural characteristics which were obtained by modelling XRD patterns. XRD patterns were recorded under controlled relative humidity (RH). The hydrated states of Ca-Hectorite were more homogeneous than those of saponite whereas the transition from 1W to 2W occurred at lower RH rates for saponite than for Hectorite. For heterogeneous samples, the 1W and 2W layers were stacked randomly for Hectorite. Na-saponite-0.4 and Ca-saponite-0.4 were made up of types of layer; one water layer (1W) and two-water layers (2W). The stacking of these layers showed some segregation.
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ChargelocationeffectonthehydrationpropertiesofsyntheticsaponiteandHectorite saturated byNa+, Ca2+cations:XRDinvestigation
Applied Clay Science, 2009Co-Authors: M.s. Karmous, J.l. Robert, H. Benrhaiem, B. Lansonc, A. Benhaj AmaraAbstract:Thispaperaimsatcomparingtheeffectofchargelocationonthehydrationpropertiesof twotrioctahedral syntheticminerals:saponiteandHectorite. Thesampleswerecharacterisedbyalayerchargeof 0.4charge perhalfunitcellandweresaturatedwithNa+orCa2+. Thehydrationbehaviourwasstudiedbydetermining thestructural characteristicswhichwereobtainedbymodellingXRDpatterns. XRDpatternswererecordedundercontrolledrelativehumidity(RH). Thehydratedstatesof Ca-Hectorite weremorehomogeneousthanthoseofsaponitewhereasthetransitionfrom1Wto2WoccurredatlowerRH rates for saponitethanfor Hectorite. For heterogeneous samples, the1Wand2Wlayers werestacked randomlyfashionforHectorite. Na-saponite-0.4andCa-saponite-0.4weremadeupof typesof layer; one waterlayer(1W)andtwo-waterlayers(2W). Thestackingof theselayersshowedsomesegregation.
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Simulation of the XRD patterns, structural properties of a synthetic Na-Hectorite exchanged Cu2+ and Ca2+
Z. Kristallogr. Suppl., 2007Co-Authors: M.s. Karmous, Hafsia Ben Rhaiem, Walid Oueslati, J. L. Robert, Abdesselem Ben Haj AmaraAbstract:The aim of this paper is to determine the hydration characteristics of Na-Hectorite exchanged Cu2+ or Ca2+. The number and positions of H2O molecules are determined by an indirect method based on the comparison between theoretical and experimental XRD patterns. The obtained results on air-dried Hectorite-Cu (H-Cu) and Hectorite-Ca (H-Ca) showed that these samples are characterised by 12.49 Å and 15.10 Å basal spacing respectively. These values correspond respectively to one and two water layers in the interlamellar space.
Bruno Lanson - One of the best experts on this subject based on the ideXlab platform.
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Hydration of Na-saturated synthetic stevensite, a peculiar trioctahedral smectite
Clay Minerals, 2020Co-Authors: Doriana Vinci, Martine Lanson, Valérie Magnin, Nathaniel Findling, Bruno LansonAbstract:Smectite interlayer water plays a key role on the mobility of elements and molecules, but also in a variety of geological processes. In contrast to saponite and Hectorite, whose layer charge originates from isomorphic substitutions, stevensite layer charge originates from the presence of octahedral vacancies. Despite its common occurrence in lacustrine environments, Hectorite hydration has received little attention, compared to saponite and Hectorite. Early reports mention a specific hydration behavior, however, with the systematic presence of a low-angle reflection attributed to the regular interstratification of different hydration states. The present study aims at revisiting this specific hydration behavior in more depth. Within this scope, the hydration behavior of the above three smectite varieties are compared using synthetic trioctahedral smectites of similar layer charge, and different compositions of their octahedral sheets. The chemical composition of the octahedral sheet does not appear to influence significantly smectite hydration for saponite and Hectorite. Compared to its saponite and Hectorite equivalents, H2O content in stevensite is lower by ~2.0 mmol H2O per g of dry clay. Consistent with this lower H2O content, Zn-stevensite lacks a stable monohydrated state, dehydrated layers prevailing from 60 to 0% RH. The presence of the regular interstratification of 0W and 1W layers is responsible for the low-angle reflection commonly observed for stevensite under air-dried conditions. Finally, stevensite identification method based on X-ray diffraction of heated and EG-solvated samples is challenged by the strong influence of octahedral sheet chemical composition (Zn or Mg in the present study) on Hectorite swelling behavior. The origin of this effect remains undetermined and further work is needed to propose a more general identification method.
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Classical Polarizable Force Field to Study Hydrated Hectorite: Optimization on DFT Calculations and Validation against XRD Data
Minerals, 2018Co-Authors: Ragnhild Hånde, Bruno Lanson, Vivien Ramothe, Stéphane Tesson, Baptiste Dazas, Eric Ferrage, Mathieu Salanne, Benjamin Rotenberg, Virginie MarryAbstract:Following our previous works on dioctahedral clays, we extend the classical Polarizable Ion Model (PIM) to trioctahedral clays, by considering dry Na-, Cs-, Ca-and Sr-Hectorites as well as hydrated Na-Hectorite. The parameters of the force field are determined by optimizing the atomic forces and dipoles on density functional theory calculations. The simulation results are validated by comparison with experimental X-ray diffraction (XRD) data. The XRD patterns calculated from classical molecular dynamics simulations performed with the PIM force field are in very good agreement with experimental results. In the bihydrated state, the less structured electronic density profile obtained with PIM compared to the one from the state-of-the-art non-polarizable force field clayFF explains the slightly better agreement between the PIM results and experiments.
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charge location effect on the hydration properties of synthetic saponite and Hectorite saturated by na ca2 cations xrd investigation
Applied Clay Science, 2009Co-Authors: M.s. Karmous, Jeanlouis Robert, Bruno Lanson, Ben H Rhaiem, Ben Haj A AmaraAbstract:This paper aims at comparing the effect of charge location on the hydration properties of two trioctahedral synthetic minerals: saponite and Hectorite. The samples were characterised by a layer charge of 0.4 charge per half unit cell and were saturated with Na+ or Ca2+. The hydration behaviour was studied by determining the structural characteristics which were obtained by modelling XRD patterns. XRD patterns were recorded under controlled relative humidity (RH). The hydrated states of Ca-Hectorite were more homogeneous than those of saponite whereas the transition from 1W to 2W occurred at lower RH rates for saponite than for Hectorite. For heterogeneous samples, the 1W and 2W layers were stacked randomly fashion for Hectorite. Na-saponite-0.4 and Ca-saponite-0.4 were made up of types of layer; one water layer (1W) and two-water layers (2W). The stacking of these layers showed some segregation.
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Charge location effect on the hydration properties of synthetic saponite and Hectorite saturated by Na+, Ca2+ cations: XRD investigation
Applied Clay Science, 2009Co-Authors: M.s. Karmous, Jeanlouis Robert, Hafsia Ben Rhaiem, Bruno Lanson, Abdesselem Ben Haj AmaraAbstract:This paper aims at comparing the effect of charge location on the hydration properties of two trioctahedral synthetic minerals: saponite and Hectorite. The samples were characterised by a layer charge of 0.4 charge per half unit cell and were saturated with Na+ or Ca2+. The hydration behaviour was studied by determining the structural characteristics which were obtained by modelling XRD patterns. XRD patterns were recorded under controlled relative humidity (RH). The hydrated states of Ca-Hectorite were more homogeneous than those of saponite whereas the transition from 1W to 2W occurred at lower RH rates for saponite than for Hectorite. For heterogeneous samples, the 1W and 2W layers were stacked randomly for Hectorite. Na-saponite-0.4 and Ca-saponite-0.4 were made up of types of layer; one water layer (1W) and two-water layers (2W). The stacking of these layers showed some segregation.
Yan Jing - One of the best experts on this subject based on the ideXlab platform.
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Phase equilibrium study at 220 ℃ of Li+,Mg2+∥Cl-, SiO32--H2O systerm
2016Co-Authors: Yongzhong Jia, Yan Jing, Ying Yao, Chao Zhang, Jinhe SunAbstract:Abstract. In this paper, phase equilibrium of Li+, Mg2+∥Cl-, SiO32--H2O system at 220°C was researched. The solid phases were characterized by X-ray diffraction (XRD). Lithium silicate, Hectorite, karpinskite and magnesium hydroxide were observed as solid phases. According to the analysis of XRD, the phase diagram was obtained. The phase diagram could be used as the theoretical principle for synthesis of Hectorite
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phase diagram of mgcl2 licl na2 sio3 h2o system at 200 c and synthesis of Hectorite
Materials Science Forum, 2011Co-Authors: Xiaojie Yin, Yan Jing, Yongzhong Jia, Ying YaoAbstract:Phase diagram of MgCl2–LiCl–Na2SiO3–H2O (MLSH) system at 200°C was reported. The phase diagram was designed according to the hydrothermal system in which Hectorite was formed. The solid phases were characterized by X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Lithium silicate, Hectorite and karpinskite were observed as solid phases. The presence of Hectorite in solid phases was decided by the molar ratio of MgCl2 and Na2SiO3 in the system. When the Mg/Si molar ratio exceeded a certain value, little Hectorite was formed even though there was a large amount of LiCl in the system. The reason may be that it was difficult for Li+ to replace the Mg2+ in the framework. As a versatile nanomaterial, Hectorite could be synthesized using concentrated natural brine as starting materials by hydrothermal method at 200°C. The phase diagram could be used as the theoretical principle for synthesis of Hectorite and comprehensive utilization of concentrated natural brine.
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removal of neutral red from aqueous solution by using modified Hectorite
Desalination, 2011Co-Authors: Yan JingAbstract:Abstract The object of this work was to study the modified Hectorite as effective adsorbent for Neutral Red (NR) from aqueous solution. The adsorbent capacity of modified Hectorite was discussed. The effects of surfactant content, adsorbent content, pH and adsorption temperature on the sorption of NR on modified Hectorite were studied. Experimental results showed that the equilibrium adsorption data fitted well with Langmuir isotherm and the adsorption capacity was 393.70 mg/g for the modified cetylpyridinium bromide Hectorite (CPB-Hect). Kinetic studies showed that the dynamical data fitted well with the pseudo-second-order kinetic model. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG 0 ), the enthalpy (ΔH 0 ) and the entropy (ΔS 0 ) indicated that the adsorption process was spontaneous and endothermic in nature.
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adsorption properties of congo red from aqueous solution on modified Hectorite kinetic and thermodynamic studies
Desalination, 2011Co-Authors: Chenglong Xia, Yan Jing, Yongzhong Jia, Duyuan Yue, Xiaojie YinAbstract:Abstract Two modified Hectorites have been designed and synthesized by two cationic surfactants namely cetyltrimethyl ammonium bromide (CTAB) and octadecylamine (ODA) for selective removal of the anionic dye congo red (CR) from aqueous solution. The adsorbent capacity of modified Hectorites was discussed and the optical contents of CTAB and ODA were 35% and 28%, respectively. Modified Hectorites were characterized by X-ray powder diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The effects of adsorbents content and adsorption temperature on the sorption of CR on modified Hectorites were studied. Experimental results showed that the equilibrium adsorption data fitted well with the Langmuir isotherm and the adsorption capacities were 182 and 197 mg/g for the modified cetyltrimethyl ammonium bromide Hectorite (CTAB-Hect) and ammonium bromide Hectorite (ODA-Hect), respectively. Kinetic studies showed that the dynamical data fitted well with the pseudo-second-order kinetic model. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG 0 ), the enthalpy (ΔH 0 ) and the entropy (ΔS 0 ) indicated that the adsorption process was spontaneous and endothermic in nature.
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Preparation and luminescence properties of lanthanide (Eu3+, Sm3+) complexes and their Hectorite-based composites.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2009Co-Authors: Yongzhong Jia, Yan Jing, Ying Yao, Jinhe Sun, Xiaohua WangAbstract:The complexes of europium and samarium with phthalates ligands were synthesized and characterized. The luminescence behaviors of the lanthanide complexes as well as their Hectorite-based composites were investigated by fluorescence spectra. The results indicated that the lanthanide complexes showed slightly lower intensities in Hectorite matrix than that of corresponding pure complexes. The lanthanide ion relative fluorescence intensity (LRFI) was enhanced when the lanthanide complexes were doped into Hectorite.
Laurent Charlet - One of the best experts on this subject based on the ideXlab platform.
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hydration of na ni2 and sm3 in the interlayer of Hectorite a quasielastic neutron scattering study
Journal of Physical Chemistry C, 2009Co-Authors: Oleg Sobolev, Miguel A. Gonzales, Lydie Le Forestier, Laurent CharletAbstract:Quasielastic neutron scattering experiments were performed with Na−Hectorite, Ni−Hectorite, and Sm−Hectorite samples in order to find out whether Sm3+ is present in the clay interlayer as a fully hydrated cation (outer-sphere complex), or, as it follows from neutron diffraction data analysis, it is dehydrated and bound to the clay surface (inner-sphere complex). The results obtained for the Sm−Hectorite were compared with other interlayer cations: strongly hydrated Ni2+ and relatively weakly hydrated Na+. It was found that water mobility in the Sm−Hectorite sample is very close to the water mobility in Ni−Hectorite. This is only possible if the Sm3+ ion is fully hydrated. It was shown that water molecules hydrating Ni2+ and Sm3+ exhibit diffusion mobility measurable with backscattering spectrometers. The diffusion coefficients of the exchangeable cations were found using the slow exchange approximations DNi = (0.05 − 0.14) × 10−9 m2/s and DSm = (0.04 − 0.18) × 10−9 m2/s.
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Hydration of Na+, Ni2+, and Sm3+ in the Interlayer of Hectorite: A Quasielastic Neutron Scattering Study
Journal of Physical Chemistry C, 2009Co-Authors: Oleg S. Sobolev, Lydie Le Forestier, Miguel A. Gonzales, Laurent CharletAbstract:Quasielastic neutron scattering experiments were performed with Na−Hectorite, Ni−Hectorite, and Sm−Hectorite samples in order to find out whether Sm3+ is present in the clay interlayer as a fully hydrated cation (outer-sphere complex), or, as it follows from neutron diffraction data analysis, it is dehydrated and bound to the clay surface (inner-sphere complex). The results obtained for the Sm−Hectorite were compared with other interlayer cations: strongly hydrated Ni2+ and relatively weakly hydrated Na+. It was found that water mobility in the Sm−Hectorite sample is very close to the water mobility in Ni−Hectorite. This is only possible if the Sm3+ ion is fully hydrated. It was shown that water molecules hydrating Ni2+ and Sm3+ exhibit diffusion mobility measurable with backscattering spectrometers. The diffusion coefficients of the exchangeable cations were found using the slow exchange approximations DNi = (0.05 − 0.14) × 10−9 m2/s and DSm = (0.04 − 0.18) × 10−9 m2/s.
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the dissolution of Hectorite in situ real time observations using atomic force microscopy
American Mineralogist, 2000Co-Authors: Dirk Bosbach, Laurent Charlet, Barry R Bickmore, Michael F HochellaAbstract:The dissolution of individual Hectorite (a trioctahedral smectite) particles has been observed at molecular scales in acidic aqueous solution with atomic force microscopy (AFM). A new sample preparation technique was used to attach nanometer-sized Hectorite particles to a mica substrate. The reactive surface area of individual Hectorite particles was identified and its change during a dissolution experiment was quantified. The dissolution of Hectorite under pH 2 conditions takes place exclusively at the edge surfaces. In contrast, the basal surface is completely unreactive within the investigated time scale of several hours. The short edges of the Hectorite laths were found to react somewhat more quickly than the long edges. The edge surface area represents 1.5–3.3% of the total surface area. The total surface area has been determined from the actual particle dimensions derived from AFM data to be 730 m 2 /g. The dissolution rate normalized to the reactive edge surface area (ESA) has been determined to be 7.3 × 10 −9 mol Hectorite/(m 2 -s), which represents a total surface area (TSA) normalized dissolution rate of 1.9 × 10 −10 mol Hectorite/(m 2 -s). The ESA/TSA ratio increases by about 15% within 1 h exposure to a pH 2 aqueous solution at 22 °C.
Jeanlouis Robert - One of the best experts on this subject based on the ideXlab platform.
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The Nature of Laponite: Pure Hectorite or a Mixture of Different Trioctahedral Phases?
Minerals, 2018Co-Authors: George E. Christidis, Josef Breu, Carlos I. Aldana, Georgios D. Chryssikos, Vassilis Gionis, Hussein Kalo, Matthias Stöter, Jeanlouis RobertAbstract:A series of laponites and synthetic OH- and fluorinated Hectorites prepared from hydrothermal and melting experiments at both industrial and laboratory scale were examined with XRD and FTIR (MIR and NIR) to determine their mineralogical composition and possible compositional heterogeneity. The end materials contained both Li- and Na-bearing phases. The industrial hydrothermal OH-smectites prepared at low temperatures consist of random mixed layer Hectorite-stevensite-kerolite with about 40–50% Hectorite layers, the remaining being stevensite and kerolite at roughly equal proportions. The FTIR spectra of these smectites contain, besides the main Mg3OH stretching/overtone bands at 3695–3690 and 7225–7214 cm−1, respectively, additional OH overtone bands at ~3716 and 7265 cm−1 (hydrated state). These bands might be linked to Mg2LiOH stretching modes. The melt-derived smectites are kerolite-free but still contain stevensite layers, although the preparation methods involved heating in the excess of 1000 °C. In these smectites Li might be partitioned to both octahedral and interlayer sites. Subsequent annealing of the melt-derived Mg-Li smectites caused migration of the exchangeable Li to the vacant octahedral due to the Hofmann-Klemen effect and thus decrease of the layer charge, as was indicated by the νO-D method. Hydrothermal synthesis of Mg-Li smectites at high temperature (400 °C) and pressure (1 kbar), yielded pure Hectorite without stevensite or kerolite domains.
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The Nature of Laponite: Pure Hectorite or a Mixture of Different Trioctahedral Phases?
MDPI AG, 2018Co-Authors: George E. Christidis, Josef Breu, Georgios D. Chryssikos, Vassilis Gionis, Hussein Kalo, Matthias Stöter, Carlos Aldana, Jeanlouis RobertAbstract:A series of laponites and synthetic OH- and fluorinated Hectorites prepared from hydrothermal and melting experiments at both industrial and laboratory scale were examined with XRD and FTIR (MIR and NIR) to determine their mineralogical composition and possible compositional heterogeneity. The end materials contained both Li- and Na-bearing phases. The industrial hydrothermal OH-smectites prepared at low temperatures consist of random mixed layer Hectorite-stevensite-kerolite with about 40–50% Hectorite layers, the remaining being stevensite and kerolite at roughly equal proportions. The FTIR spectra of these smectites contain, besides the main Mg3OH stretching/overtone bands at 3695–3690 and 7225–7214 cm−1, respectively, additional OH overtone bands at ~3716 and 7265 cm−1 (hydrated state). These bands might be linked to Mg2LiOH stretching modes. The melt-derived smectites are kerolite-free but still contain stevensite layers, although the preparation methods involved heating in the excess of 1000 °C. In these smectites Li might be partitioned to both octahedral and interlayer sites. Subsequent annealing of the melt-derived Mg-Li smectites caused migration of the exchangeable Li to the vacant octahedral due to the Hofmann-Klemen effect and thus decrease of the layer charge, as was indicated by the νO-D method. Hydrothermal synthesis of Mg-Li smectites at high temperature (400 °C) and pressure (1 kbar), yielded pure Hectorite without stevensite or kerolite domains
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charge location effect on the hydration properties of synthetic saponite and Hectorite saturated by na ca2 cations xrd investigation
Applied Clay Science, 2009Co-Authors: M.s. Karmous, Jeanlouis Robert, Bruno Lanson, Ben H Rhaiem, Ben Haj A AmaraAbstract:This paper aims at comparing the effect of charge location on the hydration properties of two trioctahedral synthetic minerals: saponite and Hectorite. The samples were characterised by a layer charge of 0.4 charge per half unit cell and were saturated with Na+ or Ca2+. The hydration behaviour was studied by determining the structural characteristics which were obtained by modelling XRD patterns. XRD patterns were recorded under controlled relative humidity (RH). The hydrated states of Ca-Hectorite were more homogeneous than those of saponite whereas the transition from 1W to 2W occurred at lower RH rates for saponite than for Hectorite. For heterogeneous samples, the 1W and 2W layers were stacked randomly fashion for Hectorite. Na-saponite-0.4 and Ca-saponite-0.4 were made up of types of layer; one water layer (1W) and two-water layers (2W). The stacking of these layers showed some segregation.
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Charge location effect on the hydration properties of synthetic saponite and Hectorite saturated by Na+, Ca2+ cations: XRD investigation
Applied Clay Science, 2009Co-Authors: M.s. Karmous, Jeanlouis Robert, Hafsia Ben Rhaiem, Bruno Lanson, Abdesselem Ben Haj AmaraAbstract:This paper aims at comparing the effect of charge location on the hydration properties of two trioctahedral synthetic minerals: saponite and Hectorite. The samples were characterised by a layer charge of 0.4 charge per half unit cell and were saturated with Na+ or Ca2+. The hydration behaviour was studied by determining the structural characteristics which were obtained by modelling XRD patterns. XRD patterns were recorded under controlled relative humidity (RH). The hydrated states of Ca-Hectorite were more homogeneous than those of saponite whereas the transition from 1W to 2W occurred at lower RH rates for saponite than for Hectorite. For heterogeneous samples, the 1W and 2W layers were stacked randomly for Hectorite. Na-saponite-0.4 and Ca-saponite-0.4 were made up of types of layer; one water layer (1W) and two-water layers (2W). The stacking of these layers showed some segregation.