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
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.
Pages 13- 23
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
For reactor design, many different balances (material, energy...) take place and require analytical or numerical techniques. In this study, an approach to the understanding of an electrochemical reactor is developed similar to that considered for the case of a chemical reactor. Both mass transfer and current density equations connecting the different species in solution, form a system of three differential equations. The numerical resolution is proposed in two examples:
- The copper recovery in sulfuric acid medium with a axial field reactor working in diffusion kinetic.
- The electrodissolution of iron in water with a radial field reactor working in activation kinetic.
M. Benzina, A. Ratel, A. Bellagi, G. Lacoste
Sunlight is used instead of a medium-pressure mercury lamp to perform the oxidative photocyclisation of the diarylethylene I to the pentahelicene II ; the chemical yield is the same as for the UV induced reaction.
A. M'henni, B. Ben Hassine, M. Gorsane
An isoperibol calorimeter is described ; and the device has been tested with the dissolution of [Tri (methyl hydroxy) amino methane] in HCl 0,1 M/Kg solution. Test reaction gave ΔH = 30,07 KJ mol. The results obtained with this device for the βT.C.P. dissolution in HNO3 55 Wt % lead to ΔH = -154,89 ± 0,33 KJ.mol.
A. Ben Cherifa, B. Omezzine, M. Jemal
The adsorption isotherms have been studied by different authors and recent works based on thermodynamic considerations have been published. This article is a review of the different models proposed in literature.
M. Dhahbi (ex. Hamdi)