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Tunis, Tunisia

Marouani S.,Tunis el Manar University | Marouani S.,University Paris Est Creteil | Bahri M.,Tunis el Manar University | Batis H.,Departement de Chimie | Hochlaf M.,University Paris Est Creteil
Journal of Physical Chemistry A | Year: 2010

We performed ab initio calculations to investigate the lowest triplet and singlet electronic states of the NO dimer and their mutual spin-orbit couplings. The electronic structure calculations are done using multiconfigurational approaches and a large diffuse basis set. A high density of electronic states is found favoring their mutual interactions by vibronic and spin-orbit couplings. We used our potential curves and spin-orbit couplings to discuss the mechanisms for the IR dissociation and the UV photodissociation of the NO dimer and the electronic de-excitation of NO (A2Σ-) after collision with NO (X2Π). For these reactions, multistep pathways, which involve the long-range and the molecular regions of the potential energy surfaces of the triplet and singlet electronic states of N2O 2, are suggested. A qualitative agreement between our findings and previous experimental assumptions is found. © 2010 American Chemical Society. Source


Ghizellaoui S.,Jijel University | Ghizellaoui S.,Departement de Chimie | Labiod K.,Departement de Chimie
Journal of Materials and Environmental Science | Year: 2011

In calcareous soils, groundwater Hamma supplying the city of Constantine in drinking water are responsible in large concentrations of calcium bicarbonate. These waters have a total hardness of 57 ° F. During their movement, these waters give rise to the phenomenon of scaling in systems, which can lead to serious failures (clogging pipes, sticking stop devices, loss of efficiency of heat exchangers etc...). Various methods of decarbonization as precipitation with lime or sodium carbonate or acid vaccination are commonly used. Some chemical inhibitors are sometimes added to block the germination of crystals of calcium carbonate. Our study focuses on the evaluation and inhibition of the scaling power of hard water of Hamma with chemical and electrochemical methods in the presence of sodium carbonate and potassium dihydrogeno phosphate. The study of the scaling curve gave an accelerated time scaling of 11.9min at 30°C and the increase in temperature decreases the value of time scaling. At an addition of 2 mg / L KH2PO4, 0.5g / L Na2CO3 the curve becomes a straight line, indicating the complete inhibition of scaling. For chemical tests the concentrations of 2.5mg/L of KH2PO4 and 0.18g of Na2CO3 are sufficient to reduce the total hardness of water. Source

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