The extraction and purification of polysaccharides from date seeds (Phoenix dactilyfera L.), as well as the evaluation of their antioxidant and antiglycated activities in vitro were investigated. Aqueous and oxalate extracts (PPW and PPO) were obtained by sequential extraction from date seeds powder. Sugar contents and macromolecular characteristics were estimated by colorimetric assays and size exclusion chromatography (SEC/MALS/VD/DRI). The best yield was obtained for aqueous extract PPW (1.9%). These experiments showed that all extracted samples were polysaccharides having a moderately high molecular weight (1680 and 1200 kDa for PPW and PPO, respectively). Preliminary antioxidant and antiglycated tests indicated that PPW showed even better ability in the scavenging of DPPH• and NO• radicals and the inhibition of lipid peroxidation and protein glycation. These findings suggest that water-soluble polysaccharides from date seeds could be explored as free radical scavengers and protein glycation inhibitors.
W. Marzouk, M.A. Chaouch, J. Hafsa, D. LeCerf, H. Majdoub
Phoenix dactilyfera L., date seeds, polysaccharide, antioxidant activitiy, antiglycated activity
Pages 124-130
The aim of this paper is to study the date seeds potential for azo dye biosorption of from aqueous solution. As shown in SEM analysis, treated date seeds were found to be effective in methyl orange dye removal. Thermodynamic parameters depicted the exothermic nature of biosorption and the process was feasible and spontaneous at all temperatures (293-313 K). Kinetic results showed that the pseudo-second-order kinetic model was well fitted to the experimental data and indicated that the biosorption was classified as chemical process. The Langmuir and Dubinin–Radushkevich (D–R) isotherm models were applied to the equilibrium data. Adsorption data were well described by the Langmuir and the maximum uptake of methyl orange onto date seeds was found to be 47.61 mg g-1 . The mean free energy for azo dye from the D-R isotherms confirms that the methyl orange was chemisorbed onto treated date seeds.
A. Rezgui, E. Guibal, T. Boubaker
Date seeds, biosorption, SEM analysis, isotherms, kinetic, chemisorption
Pages 131-136
The inhibiting effect of Laurus nobilis extract on the corrosion behaviour of patinated bronze was evaluated by means of potentiodynamic polarization, statistical experimental design, Raman spectroscopy and quantum chemical calculations. The patina layer was electrodeposited at the Cu10Sn bronze alloy in aqueous chloride electrolyte under anodic conditions. Electrochemical and Raman characterizations showed the presence of various tin oxides and crystallized as well as porous cuprite in the chloride patina layer. The statistical experimental design was investigated to model the Laurus nobilis inhibition of the patinated bronze in sulfate electrolyte. The plant extract was found to act as mixed type inhibitor. The relatively low protection efficiency was related to the synergetic effect between the experimental parameters. Quantum chemical calculations were performed with the DFT method at the B3LYP/3-21G basis set. The results revealed that the major molecule inhibitor could interact preferentially with tin oxide.
A. Chaabani, S. Aouadi, M. Ben Messaouda, A. Moadhen, A. Madani, N. Bellakhal, N. Souissi
Cu10Sn alloy, patinated bronze, green inhibitor, experimental design, DFT
Pages 137-146
Phosphogypsum is a waste by-product of the phosphate fertilizer industry, which is usually disposed in the environment because of its restricted use in industrial applications. The aim of this study is to reduce this environmental risk by producing calcium fluoride and sodium sulphate from phosphogypsum and sodium fluoride. To optimize this reaction, many factors have been considered such as temperature, reaction time, NaF/phosphogypsum molar ratio, stirring speed, reagents adding mode and phosphogypsum mass. The obtained results have shown that the NaF/phosphogypsum molar ratio, the reaction time and the phosphogypsum mass were the most influential parameters. Optimal conversion conditions were obtained with the NaF/phosphogypsum ratio between 1.5 and 2, at an average reaction time between 30 minutes and 120 minutes and at room temperature. In these conditions, the results are very satisfactory, in terms of quantity and quality of the obtained CaF2 and Na2SO4 , the conversion rate has exceeded 95%.
H. Douahem, H. Hammi, A.H. Hamzaoui, A. M’Nif
phosphogypsum, calcium fluoride, conversion, conditions
Pages 147-151
PVP-capped silver nanoparticles (Ag@PVP) were synthesized through a chemical reduction method using sodium borohydride (NaBH4) as reducing agent in an aqueous medium. The as-prepared nanoparticles were characterized using a Transmission Electron Microscope (TEM), UV-Visible, photoluminescence and Raman spectroscopies. Optical absorption measurements of Ag@PVP nanoparticles showed a strong localized surface plasmon resonance (LSPR). SERS experiments highlighted the regioselective adsorption of PVP on the Ag surface via the Ag-O interactions and the stability of Ag@PVP nanoparticles. The biocompatibility of these nanoparticles was studied using cytotoxicity experiments against HUVEC cells.
C. El Baher Dhafer, A. Mezni, L.S. Smiri
Silver nanoparticles, Raman-SERS, Ag-O interactions, Biocompatibility, Cytotoxicity
Pages 152-157
Iron molybdate NaMnFe(MoO4)3 has been synthesized by flux method and solid state reaction, and characterized by X-ray diffraction, magnetic susceptibility and ionic conductivity. This compound is isostructural with α-NaFe2 (MoO4)3 and crystallizes in the triclinic space group PĪ with the cell parameters: a = 6.963(3) Å, b = 6.998(1) Å, c = 11.169(2) Å, α = 79.88(1)°, β = 84.01(3)°, γ = 80.81(3)° and Z = 2. Its structure is built up from [Mn,Fe]2O10 units of edge-sharing [Mn,Fe]O6 octahedra which are linked to each other through the common corners of MoO4 tetrahedra. The resulting anionic three-dimensional framework leads to the formation of channels along the [101] direction, where the Na+ cations are located. The disordered distribution of iron and manganese in the same site is confirmed by bond valence calculation. Magnetic measurements show that this compound to be antiferromagnetic with Cm = 9.03 emu K/mol and θ = -65.5 K. Ionic conductivity results of the title compound reveal an activation energy Ea = 0.95 eV noticeably higher than Ea < 0.36 eV observed for NaMFe(MoO4)3 (M = Ni, Zn) . This disparity can be related to the difference between the structural characteristics of both kinds of compounds.
M. Mhiri, A. Badri, M.L. Lopez, C. Pico, M. Ben Amara
Iron molybdate; X-ray diffraction; Magnetic measurements; Ionic conductivity
Pages 158-167
During this work, we are interested in the synthesis of π-conjugated azadienic ligand, and their coordination study to two transition metals Rhenium and Ruthenium; we report also in this paper, the luminescence properties of some mono and binuclear complexes of Re(I) with 2-azabutadiene [1], furthermore, the study of their reactivity toward some nucleophiles. Ligand and complexes structures have been confirmed by IR, 1H and 13C NMR spectroscopic data.
A. Ben Esseghaier, M. Askri
2-azabutadienes, cycloaddition; rhenium, ruthenium, luminescence
Pages 1-7
Various β, β’-dihydroxythioethers, derived from oxirane were readily converted to their corresponding new mono-substituted thioethers dithiols in good yields, by treatment with thiourea and hydrochloric acid in aqueous solution. The method is applicable to aliphatic and functional diols as well as primary and secondary alcohols.
I. Gara Dallali, H.M. Sbihi, M.M. Chaabouni, M. Romdhani-Younes
hydroxythioethers, thiols, thiourea
Pages 8-12
Rss feed of the articles