Papers by hafsia ben rhaiem
New Journal of Chemistry
Pd/ZnO/APC nanocomposite-modified glassy carbon electrode (GCE) for voltammetric detection of car... more Pd/ZnO/APC nanocomposite-modified glassy carbon electrode (GCE) for voltammetric detection of carbaryl pesticides.
Journal of Hazardous Materials Advances
Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe... more Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe 2 O 3), magnetite (Fe 3 O 4) and maghemite (γ-Fe 2 O 3). Solid propulsion technology nanoparticulate materials, such as hematite and maghemite, exhibit high performance on thermal decomposition of ammonium perchlorate. The enhanced catalytic effect of metallic iron oxide nanoparticles is attributed to their particle size, more active sites and high surface area, which promotes more gas adsorption during thermal oxidation reactions. Nowadays, metallic iron nanoparticles can be synthesized via numerous methods, such as co-precipitation, sol-gel, microemulsion, or thermal decomposition. Although there are data on these synthetic methods in the literature, there is a lack of details related to nanoparticulate oxides and to their characterization techniques. In this context, this short review based on scientific papers, including data from the last two decades, presents methods for obtaining nanoparticulate iron oxides as well as the main aspects of the different characterization techniques and also about the decomposition aspects of these nanomaterials. Morphologies and structures of iron oxides can be characterized through transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. As for textural properties, they are usually determined by physical adsorption techniques.
Applied Clay Science, 2009
This paper aims at characterizing the structural evolution and the selectivity of a dioctahedral ... more This paper aims at characterizing the structural evolution and the selectivity of a dioctahedral smectite (i.e. Wyoming montmorillonite) saturated with two different couples of cations. A reference sample was prepared by saturation with Ca2+, Cu2+ or Ni2+. The clay was dispersed in solutions of (Ca2+ and Cu2+) or (Cu2+ and Ni2+). The quantitative analysis of XRD patterns is achieved using
Keying of lithium chloride alkali halide salt into the interlamellar space of nacrite clay minera... more Keying of lithium chloride alkali halide salt into the interlamellar space of nacrite clay mineral leads to a stable hybrid material that after calcination under inert atmosphere at 723 - 873 K in- duces an amorphous metahybrid. The electrochemical impedance spectroscopy (EIS) was per- formed to investigate the electric/dielectric properties of the hybrid with various parameters: frequency and temperature. Equivalent circuit was proposed to fit the EIS data. The experiment results show that the ionic conduction mechanism is related to the motion of Li+ cations which are thermally activated, named the hopping model. Furthermore, the resulting metahybrid obtained from dehydroxylation of the formal hybrid shows a superionic behavior with high ionic conductiv- ity up to 10 −2 S·m −1 , good electrochemical stability and can be used as a solid electrolyte material for Li-ion batteries.
2014 International Conference on Composite Materials & Renewable Energy Applications (ICCMREA), 2014
In this paper, we present an experimental study about the functionalization of a Tunisian nacrite... more In this paper, we present an experimental study about the functionalization of a Tunisian nacrite with a hydrated magnesium chloride salt. The elaborated nanomaterial composite have been studied via X-ray diffraction, IR spectroscopy and EDXS. The quantitative XRD analysis allowed us to determine the structural parameters related to the number and position along the normal of the layers of the alkaline bivalent cations Mg2+, halide anions Cl- and water molecules in the interlamellar space. The obtained results showed that the basal spacing value shifted from 0.72 nm related to the unexpanded nacrite to 1.5 nm attributed to the nacrite/MgCl2.6H2O composite. The existence of intercalated water is verified by infrared spectroscopy, and revealed that the active groups on the nacrite layers and the intercalated species are linked by hydrogen bonds. Moreover, microstructure investigation by transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDXS) wer...
A series of nanohybrid materials with different (CsCl) n normalities ( n = 0.05 N , 0.1 N , 0.3... more A series of nanohybrid materials with different (CsCl) n normalities ( n = 0.05 N , 0.1 N , 0.3 N , 0.5 N , 1 N , 2 N and 3 N ) was synthesized by indirect intercalation of nacrite. Systematic and kinetic X-ray diffraction surveys reveal that the optimal nanohybrid with the highest intercalation rate (τ = 0.943) and degree of reaction (α = 0.860) corresponds to ( n = 0.3 N ) normality value of aqueous CsCl solution and was labeled nacrite-[(CsCl) n = 0.3 N ]. Its half-unit cell structural formula as deduced by agreement between experimental and simulated patterns (R p = 7.30%) was Si 2 Al 2 O 5 (OH) 4 ·CsCl·H 2 O with a d 002 -value equals to 1.05 nm. The atomic composition and the vibrational description of the nacrite-[(CsCl) n = 0.3 N ] nanohybrid was made respectively by means of energy-dispersive X-ray spectroscopy coupled to transmission electron microscope and infrared spectroscopy techniques. The electrochemical impedance spectroscopy reveals that nacrite-[(CsCl) n = 0....
This work aims at examining the effect of an applied hydrous strain on the cation exchange proces... more This work aims at examining the effect of an applied hydrous strain on the cation exchange process of a dioctahedral smectite by quantitative XRD analysis. The hydrous constraint is created by a continuous, in situ, hydration–dehydration cycles using variation of %RH (relative humidity) rate. In order to examine the effect of the retained materials stress on the cation exchange capacity of the host materials, the starting, the intermediate and the final stressed samples are deposed in contact with saturated Cd(II), Co(II), Zn(II) and Ni(II) chloride solutions. To characterize structural changes, an XRD profile modeling approach is used. This investigation allowed us to determine parameters related to the nature, abundance, size, position, organization of exchangeable cation and water molecule in the interlamellar space, along the c * axis. Qualitatively, the hydration behavior is affected by the number of hydration–dehydration cycle, and an interstratified hydration phases due proba...
Wyoming Montmorillonite (i.e SWy) is a clay mineral with ‘‘TO- T” layer consisting of an octahedr... more Wyoming Montmorillonite (i.e SWy) is a clay mineral with ‘‘TO- T” layer consisting of an octahedral sheet sandwiched by two tetrahedral sheets. Isomorphic substitutions in octahedral and/ or tetrahedral sheets commonly make the clay platelets negatively charged, which are compensated by exchangeable cation. Water and other polar solvents can enter interlayer regions and cause clay-swelling. In addition, clays are able to retain inorganic and organic pollutants, and to stop the circulation of contaminated fluids in both aquatic and soil environments. Several works studied exchange process realized when clays mineral is in contact with solutions containing only one metallic cation [1-4] and shows a different hydration behavior related to the nature of exchangeable cation. The selective exchange problem was imposed when several metallic cation are present in solution, which is the most realistic case if we wants to apply clay properties in the context of industrial waste storage [5]. T...
Progress in Natural Science: Materials International, 2013
This work aims at investigating the strain effect, created by varying pH solution and continuous ... more This work aims at investigating the strain effect, created by varying pH solution and continuous heating cycle, on the cation exchange process in the case of Na-rich montmorillonite sample in contact with bi-ionic solution with variable concentration, saturated respectively by Co 2þ and Cu 2þ cations. The ionic exchange process is characterized using XRD analysis obtained through the comparison of experimental XRD patterns with calculated ones, which allowed us to determine several structural parameters related to the nature, abundance, size, position and organization of exchangeable cation and water molecule in the interlamellar space along the c n axis. Indeed, the proposed theoretical models, for the stressed samples, show that the structure presents an interstratified hydration character and proves the coexistence of more than two ''crystallite'' specie in the structure. The perturbation types have an obvious effect on the selective exchange process for all stressed samples, where the interlayer space is characterized by the coexistence of more one exchangeable cation.
Zeitschrift für Kristallographie Supplements, 2007
Desalination, 2011
ABSTRACT
This paper aims at characterizing the structural evolution of a dioctahedral smectite (i.e. Wyomi... more This paper aims at characterizing the structural evolution of a dioctahedral smectite (i.e. Wyoming montmorillonite) saturated by Na + , Cu 2+ or Pb 2+. Hydration properties of the <2μm size fraction of Wyoming montmorillonite smectite (SWy) source clay (low charge i.e. 0.35) were studied by modelling of X-ray diffraction (XRD) patterns recorded under controlled relative humidity (RH) conditions on Na, Cu or Pb saturated specimens. The Cation Exchange Capacity (CEC) of the starting sample was first Na + saturated to guarantee better dispersion, followed by exchanges with the cations Cu 2+ or Pb 2+. The resulting complexes were respectively labelled Wy-Na, Wy-Cu and Wy-Pb. The qualitative analysis of XRD patterns obtained under room pressure and temperature conditions showed that all complexes have one water layer hydration state. In order to highlight the specific hydration properties of each complex, we studied the XRD patterns under controlled relative humidity (%RH). The quantitative analysis of XRD patterns is achieved using an indirect method based on the comparison of experimental XRD patterns with calculated ones. This quantitative study showed that for Wy-Na, Wy-Cu and Wy-Pb at low RH (≈15%) the d 001 spacing corresponds to a low hydration state characterized by one water layer, whereas for higher studied rates of relative humidity (75%), differences of hydration state can be distinguished for Wy-Na, Wy-Cu and Wy-Pb samples.
Glass Physics and Chemistry
2014 International Conference on Composite Materials & Renewable Energy Applications (ICCMREA), 2014
Powder Diffr., 2013
This work aims to investigate the hydration behavior and structural properties of two dioctahedra... more This work aims to investigate the hydration behavior and structural properties of two dioctahedral smectites with contrasting location charge (beidellite SbId-1 and montmorillonite SWy-2) according to the nature of the bivalent compensator heavy metal cations (i.e. Hg (II), Ni (II), Ba (II) and Mg (II)). This study is achieved using XRD profile modeling approach based on the simulation of the 00l reflection which allowed us to determine structural characteristics along the c* axis related to the nature, abundance, size, position and organization of exchangeable cation and water molecule in the interlamellar space along the c* axis. The obtained results show that a heterogeneous hydration behavior is systematically observed in all studied samples and the structural models, used to fit samples with tetrahedral charge, are more heterogeneous than smectite with an octahedral sheets substitution. In the case of exchanged beidellite specimen, the proposed models are described by a mixed layer structure with variable abundance containing respectively, dehydrated (0W), mono-hydrated (1W) and bihydrated (2W) layers. Whereas, in the case of the montmorillonite, the absence of 0W hydration state is noted.
Journal of Environmental Chemical Engineering, 2014
ABSTRACT
Desalination and Water Treatment, 2013
The clay mineral membrane is increasingly used, as a natural geological barrier, in wastewater tr... more The clay mineral membrane is increasingly used, as a natural geological barrier, in wastewater treatment. The variation of the environmental condition (T, P, RH, etc.) induces probably several change on the materials structure. This work aims at characterizing the link between dehydration-hydration behavior, charge location, and the ionic radius, in the case of dioctahedral smectites, exchanged with Na + and Cs + cation, which are occurred from industrial waste. A natural montmorillonite and beidellite, with different charge location (respectively, dioctahedral and trioctahedral), are selected. The exchange process is directed using Na + and Cs + cations. The hydration hysteresis is investigated "in situ" as a function of relative humidity condition rates. All samples are studied using quantitative X-ray diffraction (XRD) analysis. This method allows us to determine the structural parameters obtained from the theoretical mixed layer structure used to fit experimental XRD patterns. For both Na + and/or Cs + exchangeable cations, an increase in hydration heterogeneity degree for the tetrahedral substituted smectite layer is noted and the position of exchangeable Cs + cation induce a homogeneous hydration trend which is interpreted by a new interlamellar space organization.
The goal of this paper is to examine, by quantitative XRD analysis, the effect of concentration o... more The goal of this paper is to examine, by quantitative XRD analysis, the effect of concentration of wastewater solutions saturated by (Cu 2+ , Co 2+) on the selective exchange process in the case of Na-rich Montmorillonite sample(i.e Wyoming Montmorillonite). The quantitative analysis of XRD patterns is achieved through the use of an indirect method based on the comparison of the XRD experimental patterns to the calculated ones. For the solution containing (0.5Cu 2+ and 0.5Co 2+) it is shown that for high metals concentrations (i.e. 10-1 N) the host material present homogeneous 2W hydration state (i.e 2W: two water sheet) characterized by d 001 =15.17Å basal spacing value that is attributed to Co 2+ cation. The exchange process was stopped for a limit concentration values (i.e.10-3 N) characterized by a weak ions population and which does not saturate the intrinsic cation exchange capacity (i.e. CEC) of the host materiel. Indeed, it is noted that the abundance of saturated Co 2+ clay fraction increase with concentrations and for low normality, clay remain homogeneous with 1W hydration state, which is probably attributed to Na + and/or Cu 2+ cation.
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Papers by hafsia ben rhaiem