JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Variations de la composition en acides gras polyinsaturés (w3) chez Diplodus annularis des côtes tunisiennes

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Health virtues of Mediterranean diet are particularly due to fish consumption. The beneficial effect of sparidae among other fish species with high polyunsaturated fatty acid levels is in cardiovascular and tumoral disease preventions. In our study we followed the polyunsaturated fatty acid level variations in an immature sparida species Diplodus annularis collected from three regions of Tunisian coasts north (Golf of Tunis), East (Monastic) and the south (Djerba - Zarzis). The results obtained by gas chromatograph with capillary column show the following composition of total fatty acids in the north 2.94, in the center and in the south 1.42 nigig dry matter. The statistical analysis reveals a significant difference in favour of the north value compared to those of the center and the south (P < 0,05). Moreover, our results indicate a higher level of polyunsaturated fatty acids (w3) in favour of the northern region.

A. Chaouch, I. Bouhlel, R. Sakly, I. Chraief, M. Hammami

Polyunsaturated fatty acids, Fishes, Tunisian coasts

Pages 65-75

Influence de divers facteurs relatifs à l'oxydation électrochimique du Cr(III) en Cr(VI) sur les rendements chimique et faradique

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The objective of this work is to adapt, in industrial domain, the parameters that influence the electrochemical oxidation of the Cr(III) in Cr(VI) such as the quantity of electricity, the concentration of the trivalent chromium, the nature of the medium (sulphate or chloride), the temperature and pH of reactional medium. The results obtained from the experimental design show the important influence of pH, the ionic medium and temperature on the chemical yield (RC), whereas the quantity of electricity, the nature and the pH of the medium have an important influence on faradic yield (RF).

A. Ouejhani, F. Hellal, M. Dachraoui, G. Lallevé, J.F. Fauvarque

Electrochemical oxidation, chromium(III), chromium(VI), chemical yield, faradic yield, experimental design, chemometrics

Pages 77-86

Détermination des hydrocarbures aromatiques dans les moules de la lagune de Bizerte (Tunisie)

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Mussels samples, which are considered bioindicateurs of pollution, were collected from three mytiliculture stations in Bizerte lagoon, situated in the extreme north of Tunisia during two seasons (summer and winter). The aim of this study is to determine total aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAH) in mussels samples to evaluate the state of pollution in Bizerte lagoon. Among 21 PAHs analysed 16 are included in the priority pollutants list of the US Environmental protection Agency (EPA). PAHs and total hydrocarbons was carried out respectively by GC-MS and Fluorescence-UV. Analysis of total mussel flesh in samples collected from Bizerte lagoon show that PAHs are low and variable and concentrations of total aromatic hydrocarbons are less than 100 μg/g (dry weight).

N. Mzoughi, M. Dachraoui, J. P. Villeneuve, C. Cattini, A. El Abed, S.J. De Mora

PAH, aromatic hydrocarbons, mussels, Bizerte lagoon, GC-MS, UV-F

Pages 87-93

Inversion de l'effet de Joule-Thomson dans les gaz à faible facteur acentrique

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Inversion data for the low acentric factor gases (N2, O2, Air, CH4, Ne, Ar) are correlated with a simple model Pr = 32.771 - 60.859e-Tr - 6.535Tr in terms of the reduced temperature and pressure Tr and Pr. The so obtained differential inversion curve has a peak located at (Tr = 2.23, Pr = 11.66) and its maximum reduced inversion temperature at zero pressure is 4.95. The fitting technique used is based on the structural optimization method developed by Wagner.

K. Fnena, Kh. Mejbri, A. Bellagi

Joule-Thomson effect, inversion curve, corresponding state correlation, structural optimization

Pages 95-106

Distillation membranaire à poche d'air : Application à la rétention de solutés ioniques et organiques

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In the last years, the membrane distillation has been the subject of numerous investigations in various application fields. Presented herein are the main results of an experimental study, using the air gap membrane distillation (AGMD), relative to the retention of ionic species and aqueous solution of Red Congo. The effects of the operating conditions (temperature and the concentration of salt or dye) upon the permeate flux have been studied. This study has determined the optimal operating temperature of the pilot (333 K) and showed that the concentration of the feed solution has insignificant effect upon the permeate flux. Rates of retention of 100% have been obtained for ions as well as for dye. The main results are discussed and compared to those found in the literature.

S. Bouguecha, M. Dhahbi

Membrane distillation, AGMD, Dye, Red Congo aqueous solutions

Pages 107-114

Synthèse et étude physico-chimique de fluoroapatites mixtes à cations bivalents Pb-Cd, Pb-Sr et Sr-Cd

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A continuous series of solid solutions Pb-Sr and two partially series Pb-Cd and Sr-Cd fluoroapatites, has been prepared in aqueous medium. They were characterized by X-ray diffraction, infrared absorption spectroscopy and chemical analyses. The obtaining of total solid solutions is assigned to the similarity of cationic lead and strontium radii. However for the two other systems the difference of cationic size as well as the strong polarisability of the cations limit the miscibility to 50% Cd atoms for one and 60% for the other. The lattice parameters a, c and the volume v, vary linearly with the atorm% of the cation substituted.

A. Hamad, B. Badraoui, M. Debbabi

Fluoroapatite, cationic substitution, solid solution, X-ray-diffraction

Pages 115-124

Calcul ab-initio des intégrales de transfert, structure de bande et surface de Fermi du (TMTSF)2PF6 et du (TMTTF)2PF6

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ab-initio calculations have been carried out in order to compute transfer integrals between neighboring cation molecules in TMTYF (Y = S, Se) families. Both full and Dimer-Splitting approximation based calculations were performed. Different basis sets have been tested. Results present a great coherence degree with semi-empirical results and a relative basis set independence. It has been proved that the band structure and the Fermi surface of these salts vary according to the physical-chemical constraints. Referring to the experimental crystallographic structure determined at some values of pressure and/or temperature, we have proposed a subtle analysis of these variations and of the topology of Fermi surface.

K. Essalah, S. Krichene, B. Tangour, M. Abderrabba

Transfer integrals, TMTSF, TMTTF, band structure, Fermi surface, Nesting vectors

Pages 125-135

Synthèse et caractérisation des complexes phosphorylés de Zn(II) et Cd(II) par RMN

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Two new complexes Cd[Et2NP(O)F2]4(ClO4), and Zn[Et2NP(O)F2]4(ClO4)2 have been synthesized and characterized by multinuclear NMR (31P, 19F and 113Cd). The results obtained showed a correlation between the nature of the substituents around the P atom and the reactivity of the P = X sites towards cadmium and zinc for E = O and E = S.

M. A. M. Khouna, M.T. Ben Dhia, M.M. Chaabouni, A. Baklouti, M.R. Khaddar

Diethylaminodifluorophosphine oxide, Metallic cations, Coordination chemistry, NMR

Pages 137-144

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