JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Influence des impuretés sur le comportement électrochimique d'électrodes dans la soude 0.1 N

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The fact that mixed potential of aluminum in a 0.1 N NaOH solution at 60°C is more negative when the metal is purer can be readily explained by potential v s. time plots and volumetric measurements. these are consistent with impurities behaving as microcathodes which shift the mixed potential of pure aluminum towards higher potentials, the corrosion velocity being enhanced correlatively.

E. Triki

Pages 51-54

Teaching : Domaine de définition d'un système thermodynamique

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Any thermodynamical investigation should be preceded by a precise definition of the "Thermodynamical System" (Material System) connected with this investigation. It is possible to extend the usual definition of a Thermodynamical system and to emphasize the fact that such a system is indeed a particular element in a well given set. These sets, we have called "Existence fields of Thermodynamical Systems", may be defined in a rigourous way by means of some conventions issued from an adapted terminology. Such a thermodynamical phenomena concept enables us to investigate, in an original manner, in-equilibrial material system and specially phase diagrams.

J. Belguith, J. L. Janier Dubry

Pages 59-63

Synthèse de monoacides α-amines N-alkyles et N,N-dialkyles par monocondensation du chlorhydrate de sodium sur des amines primaires et secondaires

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The study of sodium chloracetate monocondensation on certain primary and secondary amines with hydrocarbonus chains which are either linear or ramified or cyclic, has enabled us to synthesize nine α-aminoacids. We have purified those α-aminoacids by preparing their chlorhydrates.

F. M'henni, Z. Mighri

Pages 3-12

Etude par spectroscopie infra-rouge de l'adsorption d'oxygène sur γFe2O3 : Interaction avec H2, H2O et CH2=CH-CH3

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The reaction of oxygen with the surface of γFe2O3 has been studied by infrared spectroscopy method. It has been shown that a variety of forms of adsorbed oxygen is produced. The adsorption bands corresponding to the different forms of adsorbed oxygen lie in the 1600 - 800 cm-1 spectral range. Two species are clearly distinguished: one neutral molecular specie highly polarised which absorbs in the 1500-1540 cm-1 region and one charged specie O2n- with 0 < n < 1 which absorbs in the 1500 - 1200 cm-1 region. Their thermodesorption in vacum at 250°C is accompanied by sample reduction to Fe3O4 state. Hydrogen reacts selectively (according to temperature) with adsorbed molecular oxygen then lattice oxygen. With molecule interacts physically among hydrogen bonds with some O2n- species, however dipole-dipole interaction with polarized species is pointed out. At room temperature, propen adsorption leads to chemisorbed species obtained by a reaction with adsorbed oxygen.

H. Batis

Pages 13- 23

Etude de la fixation du magnésium d'un milieu phosphorique sur résines échangeuses d'ions

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The fixation of magnesium in phosphoric acid medium is studied on different types of cation exchange resins. On account of its high exchange capacity, the sulfonic resin Duolite C 20 is kept to check the factors (pH and metal concentration) governing the exchange phenomenon. After determination of the exchange constant the square diagram representative of the equilibria between phases is traced.

M. Feki, M. Chaabouni, H.F. Ayedi

Pages 25-35

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