Abdelhamid Ben Salah

Elaboration of new ceramic microfiltration membranes from mineral coal fly ash applied to waste water treatment

This work aims to develop a new mineral porous tubular membrane based on mineral coal fly ash. Finely ground mineral coal powder was calcinated at 700 degrees C for about 3 h. The elaboration of the mesoporous layer was performed by the slip-casting method using a suspension made of the mixture of fly-ash powder, water and polyvinyl alcohol (PVA). The obtained membrane was submitted to a thermal treatment which consists in drying at room temperature for 24 h then a sintering at 800 degrees C. SEM photographs indicated that the membrane surface was homogeneous and did not present any macrodefects (cracks, etc...). The average pore diameter of the active layer was 0.25 microm and the thickness was around 20 microm. The membrane permeability was 475 l/h m(2) bar. This membrane was applied to the treatment of the dying effluents generated by the washing baths in the textile industry. The performances in term of permeate flux and efficiency were determined and compared to those obtained using a commercial alumina microfiltration membrane. Almost the same stabilised permeate flux was obtained (about 100 l h(-1)m(-2)). The quality of permeate was almost the same with the two membranes: the COD and color removal was 75% and 90% respectively.

Structure and ionic conductivity of the lacunary apatite Pb6Ca2Na2(PO4)6

Abstract Polycrystalline Pb 6 Ca 2 Na 2 (PO 4 ) 6 (NCPbAp) was obtained via a solid state reaction. It was characterized by IR spectrometry and X-ray diffraction, its structure was refined using the Rietveld method. It crystallizes in the hexagonal system (s.g. P 6 3 / m , a =9.658(8) A and c =7.081(6) A) and presents a lacunary structure stabilized by the electron lone pair of lead (II) ions. At 720 K, an order–disorder phase transition probably of first order is observed either in conductivity or XRD studies versus temperature. Electric conductivity is dominated by the mobility of sodium in the tunnels.

Crystal structure and electrical behavior of the new ceramic Ba0.7Na0.3Ti0.7Nb0.3O3

The crystal structure of the new Perovskite ceramic Ba0.7Na0.3Ti0.7Nb0.3O3 has been refined by the Rietveld method from X-ray powder diffraction data. The title compound crystallizes at room temperature in the cubic space group Pm¯ 3m with a = 3.9849(1) Aa ndZ = 1. The Rietveld refinement converged to the final crystal structure and profile indicators Rwp = 21.0, RB = 5.3. A ferro-paraelectric phase transition was detected by differential scanning calorimetry and dielectric measurements showing a relaxor behavior in this material.  2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

Crystal structure, DSC and Raman studies in CH3C6H4NH(CH3)2·SbCl4

Abstract The salt para methyl phenyl dimethyl ammonium tetrachloroantimonate (III) crystallizes in the monoclinic system with space group Cc. The unit cell dimensions are: a=13.780(1) A, b=14.943(2) A, c=8.192(1) A, β=113.39(1)°, with Z=4. The structure consists of ammonium cations and polynuclear anions in which distorted SbCl5 square pyramids sharing a common Cl atom are held together in infinite chains parallel to the c axis. These chains are themselves interconnected by means of the NH⋯Cl hydrogen bonds. Differential scanning calorimetry study was carried out. The Raman of polycrystalline samples have been recorded at different temperatures between 77 and 300 K. A low-temperature phase transition at 230 K of order-disorder type was found.

X-Ray diffraction, DSC and Raman studies in [C12H18N]2BiCl5 · H2O

The salt bis (N-benzylpiperidinium) pentachlorobismuthate (III) monohydrate crystallises at room temperature in the monoclinic system with space group P21/c, the unit cell dimensions are: a = 12.241(1), b = 8.787(1), c = 27.787(1) Å, β = 99.6(1)°, with Z = 4. The structure has been refined to R = 0.0427. The structure shows a layer arrangement parallel to the a axis: planes of the [BiCl10]4− bioctahedra alternate with planes of N-benzylpiperidinium cations. The [BiCl10]4− bioctahedra are connected through O(W)–H···Cl hydrogen bonds, so that infinite unidimensional chains of composition are formed in the structure parallel to the a axis. These chains are themselves interconnected by means of the N–H ··· Cl bonds originating from the [C12H18N]+ entities, forming a three-dimentional network. DSC and Raman spectroscopic measurements were carried out and reveal a transition at T = 334 K (Phase I −(334 K) →Phase II). This transition displays a displacive and order-disorder mechanism involving mainly reorientational motion of the organic cations coupled with distortion of the BiCl6 octahedra.

Crystal structure of tris (phenylammonium) chloride pentachloroantimonate (III) monohydrate

AbstractThe tris (phenylammonium) chloride pentachloroantimonate (III) monohydrate salt is triclinic

N-Methyl­isosalsoline from Hammada scoparia

P\bar 1

Antioxidant and α-amylase inhibitory activities of extract and isolates from Zygogynum pancheri subsp. arrhantum

with the following cell parameters: a = 9.4283(3), b = 11.4482(3), c = 13.1748(3)Å, α = 113.493(2), β = 90.381(2), γ = 97.331(1)°, V = 1290.86(6)Å3, with Z = 2 formula units. The structure consists of [C6H5NH3]+ cations, water molecules, Cl− anions, and SbCl5 square pyramids. Hydrogen bonds, established through water molecule, link the anions [SbCl5]2− and Cl− and make an infinite chain in the [011] direction. Chains are linked together via another hydrogen bond network originating from the ammonium groups. A distortion of the SbCl5 square pyramid can be attributed to the stereo activity of the Sb(III) lone electron pair.