JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Fats in seeds of four species of cucurbitaceae from Congo

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Oils from 4 species of cucurbitacae from Congo (Citrullus lanatus, Cucurbita moschata, Cucurbita pepo, Lagenaria siceraria) were studied. The oils are of the linoleic type and have in general more than 50% linoleic acids. (C18:2, essential fatty acid) and more than 70% unsaturated fatty acids. One also finds some palmitoleic acid (C16:1) in Citrullus lanatus and some margaric acid (C17:0) in Lagenaria siceraria. Their high content in linoleic acid may suggest some instability at high temperature. However the evaluation of the alteration of these oils through their physical and chemical characteristics (viscosity, E323, E268, acid index, iodine index) and through the analysis of the fatty acids shows a behavior similar to that of peanut and olive oils. The linoleic acid content which is in all cases less than 2.5% strongly supports the idea of relatively good stability up to 170°C. These oils may be considered as good dressing oil or good oil for low temperature frying.

T. Silou, O. Kissotokene - Ntinou, M. Mvoula Tsieri, J.M. Ouamba, S. Kiakouama.

Pages 13-21

Catalytic oxidation reaction of naphthalene in sulfate-disulfate fused salts mixture at 425°C: Effect of reactants composition on reaction rate

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Naphthalene oxidation in molten mixture of potassium sulfate pyrosulfate at 425°C in the presence of vanadium pentoxide gives a vapour mixture of organic products containing mainly phtalic anhydride, 1,4-naphthoquinone and unreacted naphthalene. The best rates of naphthalene conversion and anhydride phtalic formation are obtained when mixture inlet is rich in naphthalene and has a long space time.

M.S. Medimagh, M.L. Bouguerra

Pages 23-32

Potentiometric study of Cu (I) S-HMPT complexes in acetonitrile

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Mixed complex formation reactions between CuCl and hexamethyl - thiophosphoramide (S - PMPT) have been studied, in acetonitrile at 25°C, by potentiometric measurements using a Cu (Hg) as indicator electrode. Results from graphical and numerical calculations methods demonstrated the formation of complexes. The superior order of which is equal to 3. However, the second method gives a better guarantee of precision. The results obtained by this method are β1 = 1,27.101, β2 = 1,89.102 and β3 = 3,97.103.

A. Cherni, M. Dachraoui, R. Kosai

Pages 33-44

Thin layers of Cu and in sulphides: Spray method preparation and determination of composition by electrochemical methods

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We have studied by electrochemical analytical methods the composition of CuInS2 thin layers prepared by spray of the solution Cu (I) In (III) and thiourea. The amounts of copper and indium are determined by differential pulse polarography after dissolution of thin layers in HCl 5 mol/L solution. The sulphur is determined in closed circuit as H2S, by bipotentiometry using two indicator platinum electrodes. In order to obtain thin layers stoichiometry, concentration ratios [Cu (I)] / [In (III)] = 1,1 and [Thiourea] / [In (III)] = 3 in the pulverization solution are used.

M. Mnari, M. Dachraoui, S. Belgacem, H. Latrous

Pages 45-53

Absorption heat pump: Performance coefficient

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The purpose of the research reported here is to develop one of the applications of an absorption heat pump for energy upgrading from 60 - 40°C to 120 - 150°C. After a description of the pilot plant (power 1 kw) the authors present the experimental level of upgrading and efficiency. The experimental results show that it is possible to reach 140°C with efficiency 1.4; the theoretical energy can be recovered; the experimental results approach the theoretical ones with graving size of plant.

S. Gabsi, M. Ben Zina

Pages 55-67

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