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Papers by mohamed salah karmous

Applied Clay Science, Sep 1, 2009

This paper aims at comparing the effect of charge location on the hydration properties of two tri... more 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 Ca 2+. 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.

Supplement issues of Zeitschrift für Kristallographie, Jun 1, 2006

Supplement issues of Zeitschrift für Kristallographie, Jun 1, 2006

Iranian Journal of Materials Science and Engineering, Jun 10, 2012

Atomistic simulations are carried out for zeolite with ABW framework. The structure is modeled an... more Atomistic simulations are carried out for zeolite with ABW framework. The structure is modeled and force field simulations are preformed to investigate its elastic properties, bulk, shear modulus and auxeticity. Bulk moduli (Ks), Shear moduli (G), and Poissons ratios (ν) were found to be K s =79.71725 GPa, G=16.93265 GPa, ν xy =-0.2207, ν xz =-0.5730, ν yx =-0.71717, ν yz =0.87013, ν zx =-0.33097 and ν zy =1.54568 for ABW; the negative value of Poisson's ratios reflects an auxetic behavior of material. An evaluation of the directional young's moduli shows that the compressibility of ABW is not uniform along [100], [010] and [001] axes. All calculations were performed using GULP program.

Zeitschrift für Kristallographie Supplements, 2007

The aim of this paper is to determine the hydration characteristics of Na-hectorite exchanged Cu ... more The aim of this paper is to determine the hydration characteristics of Na-hectorite exchanged Cu 2+ or Ca 2+ . The number and positions of H 2 O 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.

Zeitschrift für Kristallographie Supplements, 2007

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.

Zeitschrift für Kristallographie Supplements, 2006

World Journal of Nano Science and Engineering, 2011

Computational energy minimization techniques have been used to study the structure and crystal pr... more Computational energy minimization techniques have been used to study the structure and crystal properties of kaolinite. The full elastic tensors of the sheet silicates of clay have been derived with first-principles calculations based on density functional theory. All calculations were performed using GULP program.

Applied Clay Science, 2011

Applied Clay Science, 2011

Applied Clay Science, Sep 1, 2009

This paper aims at comparing the effect of charge location on the hydration properties of two tri... more 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 Ca 2+. 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.

Supplement issues of Zeitschrift für Kristallographie, Jun 1, 2006

Supplement issues of Zeitschrift für Kristallographie, Jun 1, 2006

Iranian Journal of Materials Science and Engineering, Jun 10, 2012

Atomistic simulations are carried out for zeolite with ABW framework. The structure is modeled an... more Atomistic simulations are carried out for zeolite with ABW framework. The structure is modeled and force field simulations are preformed to investigate its elastic properties, bulk, shear modulus and auxeticity. Bulk moduli (Ks), Shear moduli (G), and Poissons ratios (ν) were found to be K s =79.71725 GPa, G=16.93265 GPa, ν xy =-0.2207, ν xz =-0.5730, ν yx =-0.71717, ν yz =0.87013, ν zx =-0.33097 and ν zy =1.54568 for ABW; the negative value of Poisson's ratios reflects an auxetic behavior of material. An evaluation of the directional young's moduli shows that the compressibility of ABW is not uniform along [100], [010] and [001] axes. All calculations were performed using GULP program.

Zeitschrift für Kristallographie Supplements, 2007

The aim of this paper is to determine the hydration characteristics of Na-hectorite exchanged Cu ... more The aim of this paper is to determine the hydration characteristics of Na-hectorite exchanged Cu 2+ or Ca 2+ . The number and positions of H 2 O 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.

Zeitschrift für Kristallographie Supplements, 2007

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.

Zeitschrift für Kristallographie Supplements, 2006

World Journal of Nano Science and Engineering, 2011

Computational energy minimization techniques have been used to study the structure and crystal pr... more Computational energy minimization techniques have been used to study the structure and crystal properties of kaolinite. The full elastic tensors of the sheet silicates of clay have been derived with first-principles calculations based on density functional theory. All calculations were performed using GULP program.

Applied Clay Science, 2011

Applied Clay Science, 2011