Bleaching agents for the recycling process of used mineral oils are prepared from south Tunisian natural bentonitic clay via a sulphuric acid activation. The effect on the product quality of the temperature, the reaction time, the liquid/solid ratio and the acid concentration in the reaction suspension is investigated. The experimentation is conducted according to the experimental design method and a fully central composite design is used. The search for the optimal reaction conditions is performed numerically with a statistical model of the activation process.
A. Gannouni, A. Amari, A. Bellagi
bentonitic clay, acid activation, bleaching of used mineral oils, factorial design of expriments, optimization
Pages 157-171
Organic–inorganic hybrid {(C5H7N2)2[MnCl2(H2O)2]Cl2}n was synthesized from ethanol solution containing manganese (II) chloride 4-hydrat and 4-aminopyridine under acidic conditions. The compound crystallizes in the monoclinic system, (space groupe P21/c) with a=3.946(1) Å, b=17.586(6) Å, c=12.845(4) Å, β=93.48(3)°, V=889.7 (5) Å 3, Z=2, Rw(F2)= 0.095; R(F2)=0.036. The link between organic and inorganic moieties is achieved by N-H…Cl and Cl…H-O hydrogen bonds. The electronic structure and thermal properties of the title compound were also studied by UV-vis, TGA, TDA, DSC, EDX and IR.
D. Zaouali Zgolli, H. Boughzala, A. Driss
Manganèse, hybride organique-inorganique, 4-aminopyridine
Pages 173-178
The Ag0.62K0.38Nb4AsO13 compound was prepared by a solid state reaction. A qualitative analysis by scanner electronic microscope (S.E.M) and infrared (I.R) spectroscopic study were made for the state. The structural study of the Ag0.62K0.38Nb4AsO13 compound shows that this material crystallizes in the orthorhombic system (space group Cmcm) and has a three dimensional framework. There are tunnels, with hexagonal section, in where Ag+ and K+ cations are located. The characteristics derived from the structural study, which support good ion mobility, have encouraged to study the ionic conductivity through the complex impedance method.
S.F. Cherif, F. Ben Amor, M.F. Zid, A. Driss, A. Madani
S.E.M analysis, I.R spectroscopy, Structural study, C.I spectroscopy
Pages 179-190
The study of the robustness of a process related to the preparation of sulfated amide of pomace oil fatty acids has been carried out in two steps. First, we performed a Plackett - Burman screening design to select from eleven potentially influential factors those which are really influent. Second, we reduced the variation domain of the four significant factors resulted from the Plackett - Burman design and considered them among the 31 parameters which may disturb the process efficiency if little variations of their levels occur when performing the reactions. The study of the process robustness has been then carried out by applying a two-level supersaturated design related to a half fraction of a 36-experiment Hadamard matrix. The total variance of the response in this design, compared to the repeatability variance showed that the process is affected by the deliberate small variations in its parameters. Multiple regression methods namely ridge regression, stepwise selection procedure, and all-subset regressions were used to analyze the supersaturated design data. Results indicated that five factors, namely, molar ratio SO3/Ester, amidation time, amide addition rate, alkali concentration, and amidation temperature, remain active despite the decrease of their variation domain and thus they must be well controlled when performing the process.
F. Rais, A. Kamoun, M. Chaabouni, M. Claeys-Bruno, R. Phan Tan Luu, M. Sergent
Robustness, Plackett-Burman, supersaturated design, sulphate amide of fatty acids, olive pomace oil
Pages: 191-202
A new organic-inorganic hybrid material, tris(2-ammonioethyl)aminium chloride hexachlorobismuthate(III); {(C2H4NH3)3NH}4+. Cl-. [BiCl6]3-, has been synthesized and characterized by X-Ray diffraction, SEM (Scanning Electron Microscopy) and IR spectroscopy. The molecule adopts a trigonal (P -31c) cell with the lattice parameters a=10.400(3) Å, c=24.927(6) Å and Z=4. The structure exhibits isolated [BiCl6]3- octahedra leading to a 0D SBU (Secondary Building Unit) anionic network (quantum dots). The crystal cohesion is achieved by hydrogen bonds N-H…Cl between the trigonal organic molecules {(C2H4NH3)3NH}4+ , [BiCl6]3- octahedra and the isolated Cl- anions. Theoretical calculation using the PM3 approach for studying the IR vibrational spectra, shows a good agreement between observed spectrum and calculated one.
H. Ferjani, H. Boughzala, A. Driss
Bismuth (III) complex, Zero-dimensional structure, IR spectroscopy
Pages 203-209