Journal of Materials and Environmental Science

Publications
The inhibitory effect of extract of Hibiscus cannabinus on corrosion of mild steel in aqueous 0.5 M H2SO4 was investigated by weight loss method, potentiodynamics polarisation technique and electrochemical impedance spectroscopy (EIS). The inhibition efficiency of Hibiscus cannabinus extract on corrosion of mild steel in 0.5 M H2SO4 solution increases on increasing in concentration of the extract and decreases with rise in temperature. Potentiodynamic Polarization measurement indicates that Hibiscus cannabinus acts as a mixed-type inhibitor. The increase in activation energy of corrosion process in the presence of the extract indicates that the extract retards the rate of corrosion of mild steel in 0.5 M H2SO4 solution. The nature of adsorption of the extract on mild steel surface is found to obey Langmuir adsorption isotherm. EIS measurement result is also correlated with the result of polarization. SEM study confirmed the adsorption of inhibitor molecules on mild steel surface.
 
The extract of adhatoda vasica in aqueous 0.5 M H2SO4 was systematically investigated to ascertain its inhibitory effect on corrosion of mild steel and its mechanism of the inhibition by weight loss method, potentiodynamics polarisation technique and electrochemical impedance spectroscopy (EIS). The inhibition efficiency of adhatoda vasica on corrosion of mild steel in 0.5 M H2SO4 solution increases on increasing in its concentration and decreases with rise in temperature. Potentiodynamic Polarization measurement show that adhatoda vasica acts as mixed type inhibitor. The increase in activation energies of corrosion process in presence of the extract indicates that adhatoa vasica extract retarded the rate of corrosion of mild steel in 0.5 M H2SO4 solution. The nature of adsorption of the extract on mild steel surface was in conformity with Langmuir isotherm. The result of EIS was correlating with the result of polarization measurement. Scanning electron microscopy (SEM) study confirmed that the inhibition of corrosion of mild steel is through adsorption of the extract molecules on surface of metal.
 
3-Methyl-4-amino-5-mercapto-1,2,4-triazole (MAMT) was investigated for its inhibition action on the corrosion of 6061/Al - 15 (vol-%) SiC(p) composite in 0.5M sodium hydroxide solution at different temperatures by potentiodynamic polarization and electrochemical impedance spectroscopic techniques. The effect of inhibitor concentration, temperature and concentration of the corrosion medium on the inhibitor action was investigated. The inhibition efficiency increased with the increase in the concentration of inhibitor but decreased with the increase in temperature. Both thermodynamic and activation parameters were calculated and discussed. The adsorption of MAMT on the composite was found to be through physisorption obeying Langmuir's adsorption isotherm.
 
The corrosion and inhibition behaviors of mild steel in sulfuric acid + 5% EtOH in the presence of tannin extract of Chamaerops humilis plant (LF-Ch) and potassium iodide (KI) have been studied using the electrochemical methods. It was found that the inhibition efficiency increased with LF-Ch extract concentration. The addition of potassium iodide to LF-Ch extract in solution increased the inhibition efficiency of this latter. A synergistic effect was observed between KI and extract with optimum of concentration of 100 mg /L LF-Ch extract + 0.025% potassium iodide. Adsorption of extract alone or in combination with potassium iodide on the metal surface obeyed the Langmuir adsorption isotherm and thermodynamic calculations revealed that the adsorption of inhibitor were of chemical nature. That suggest the presence of iodide ions in solution increases the surface coverage. The adsorption of LF-Ch extract on the mild steel in aggressive medium leads to the formation of a protective film which grows in thickness and effectiveness with increasing exposure time.
 
The study relates to the characterization of the electrochemical behaviour of the alloy Cu-10Ni in the medium with 0,5M NaCl with and without inhibitor at the ambient temperature. The inhibiting effect of (NALCO based on amines) with various concentrations, was studied by the stationary and nonstationary electrochemical methods. The study thus underlined, a value of 35ppm, critical concentration in inhibitor at temperature 25°C, a rate of covering of the surface of 0,9243 for a maximum of effectiveness of 92,43%.Means of characterization such, cathodic and anodic polarization as well as optical microscopy and dispersive analysis X in energy (EDS), were used to characterize the external products of corrosion. A suitable equivalent land pattern was employed for calculates the various parameters. In agreement with the literature, the results of the curves of potentiodynamic polarization reveal that the inhibitor functions like an inhibitor mixed. Inhibition occurs by adsorption, creating a fall of the pH at the point of null load what returns the load of film of more negative surface with pH neutral and consequently less likely to the adsorption of species charged negatively like the ions Cl-. In comparison with the results, in agreement with the data of the literature [ ], the product of corrosion formed on alloy for a concentration of 35ppm in inhibitor, is a compound of CuÒ in the internal layer, and of CuO in the external layer. For a concentration higher than 35ppm, a porous and not-protective layer of corrosion is formed on alloy, its composition is a mixture of CuCl, Cu2O, NiO with traces of CuO and component most significant Ni(OH)2. The electrochemical spectroscopy of impedance (EIS) confirms the presence of an organic film external, playing the part of a barrier layer, protective side. The cyclic metric Volta diagrams obtained confirm the stability of protective film of the inhibitor even to the anodic potentials of +550 millivolts. All these studies indicate that the inhibitor reacts like an excellent inhibitor in the case of the alloy Cu-Nor 90/10) in the studied medium.
 
The influence of temperature on the electrochemical behaviour of stainless steel was investigated in simulated and industrial phosphoric acid. Stabilisation of the passive film was studied by potentiodynamique polarisation curves, and electrochemical impedance spectroscopy (EIS) measurements. The alloy showed active-passive behaviour in this medium, an increase in temperature resulted in an increase in the passivation current density.The passive film formed on alloy sanicro 28 in simulated phosphoric acid is less stable than formed in industrial medium.
 
In this work, we theoretically study the hydrogenation reaction of disubstituted cyclopentene 1a-d by the (Z)-1,2-diazene 2 and by (E)-1,2-diazene 2'. DFT/B3LYP calculations with 6-311G** standard basis set, explain the possibility and the stereoselectivity of these reactions. The transition states of the reaction between (Z)-1,2-diazene 2 and disubstituted cyclopentene 1a-d have been calculated and discussed.
 
A facile synthetic route for 1,2-dihydro-1-arylnaphtho[1,2-e] [1,3]oxazine-3-one/thione derivatives by one-pot three-component condensation reaction of 2-naphthol, aromatic aldehydes, and urea or thiourea in presence of snail shell as a novel, efficient, green and nontoxic catalyst, under solvent free conditions has been described. The method is associated with some attractive characteristics such as short reaction time, high yield of products, and recyclability of recovered catalyst from the reaction mixture.
 
The new derivative of 1, 2,3-triazole in basic 8-hydroxyquinoline namely ethyl 4-amino- 1-((8-hydroxyquinolin-5-yl)methyl)-1H-1,2,3-triazole-5-carboxylate (EHTC) was synthesized and characterized by NMR spectroscopic. This compound was tested as corrosion inhibitor for carbon steel in a 1.0 M HCl solution using Gravimetric, potentiodynamic polarization curves and electrochemical impedance spectroscopy. Potentiodynamic polarization curves measurements showed that the investigated compound acts as mixte-type inhibitor. Its inhibition efficiency improved with concentration and reached a maximum 91 % at 10⁻³ M. In addition, the temperature effect on the in the inhibition efficiency of EHTC was also studied in the temperature range of 298-328 K. It is found that the inhibition efficiency decreases with temperature. Indeed, the adsorption of the studied inhibitor on the mild steel was well described by the Langmuir isotherm and the calculated ΔG*ads value showed that corrosion inhibition was controlled by a chemisorptions process. Quantum chemical calculations were used to correlate the inhibition ability of EHTC with its electronic structural parameters.
 
The optimized geometries of the 1-(1-metyl-3-substituted-[1,2,4]selenadiazinyl) pyrrolidinofullerenes  
Molecular orbital spatial distribution for the HOMO and LUMO of OMe, H, COMe molecules  
In this work, Quantum mechanical calculations were carried out to study the structural and electronic properties of 1-(1-metyl-3-substituted-[1,2,4]selenadiazinyl) pyrrolidinofullerenes using the HYPERCHEM 7.52 program. Various substituents at the para position of phenyl ring were selected to understand the effect of such structural change on the electronic and structural properties of the molecules. The substituents include: OMe , SMe, N(Me)2, NH2, Me, COMe, F, Cl, and CN. All molecules optimized first using the molecular mechanics force field, and then further geometry optimization was carried out at the PM3 level of semiempirical molecular orbital theory. The optimized geometries, some of calculated energies, spatial distribution and positions of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), the difference between the HOMO and LUMO orbitals (LUMO-HOMO), known as energy band gap (δE), bond lengths, the charges of atoms and electrostatic potential finally were calculated.
 
Corrosion rate and efficiency data obtained from weight loss measurements for copper in NaCl 3% solution in the absence and the presence of bTA at 5×10 -3 M. 
The efficiency of a new corrosion inhibitor, the (bTA), on copper was investigated in an aerated 3% NaCl solution using various techniques by potentiodynamic polarisation techniques, weight loss measurements and surface analysis (SEM). Potentiodynamic polarization curves showed that (bTA) is a mixed-type inhibitor for copper in chloride solution 3% and is even more efficient than the reference compound benzotriazole. The inhibition efficiency was found to increase with concentration until 5×10-3M. The maximal protection efficiency exceeded 94.65%.
 
New 3,5-disubstituted-4-amino-1,2,4-triazole derivative, namely 3,5-bis(3,4-dimethoxyphenyl)-4-amino-1,2,4-triazole (3,4-MAT) was synthesised and its inhibitive action against the corrosion of mild steel in 1 M HCl solution was investigated at 308 K. The detailed study of 3,4-MAT was been performed using gravimetric measurements and polarisation curves method. Results show that 3,4-MAT is a good inhibitor and its inhibition efficiency reaches 98 % at·10-3 M. Tafel polarisation study revealed that 3,4-MAT acts as a mixed type inhibitor. The inhibitor adsorption process in mild steel/3,4-MAT/hydrochloric acid system was studied at different temperatures (308-323 K) by means of weight loss measurements. The adsorption of 3,4-MAT on steel surface obeyed Langmuir's adsorption isotherm. The kinetic and thermodynamic parameters for mild steel corrosion and inhibitor adsorption, respectively, were determined and discussed.
 
Theoretical electronic properties (HOMO, LUMO, Gap) obtained by B3LYP/6-31G(d) of the studied molecules
Optimized structures of studied molecules obtained by B3LYP/6-31G(d) level. 
Energy Values of E HOMO , E LUMO and the Open Circuit Voltage V oc ( eV.)
Simulated UV-visible optical absorption spectra of studied compounds with the calculated data at the TDDFT/B3LYP/6-31G (d) level. 
In this work, we report theoretical analysis on the geometries and optoelectronic properties of new small conjugated compounds based on quaterthiophene and benzo[1,2,5]thiadiazole as acceptor, these compounds were designed and studied by using density functional theory (DFT) and time-dependent (TD) calculations. The study of the structural and optoelectronic properties (HOMO, LUMO, Gap energy, Voc) is realized by using DFT method at Becke's three parameters and Lee- Yang-Parr functional (B3LYP) level with 6-31G(d) basis set. The calculations were performed by Gaussian 09 program supported by Gauss View 5.0.8 The effects of the electron-donating groups (OH, OCH3 and CH3) and electron-withdrawing groups (Cl, Br, CN and CHO) substituents on the geometries, electronic and photophysical properties of these molecules are discussed to investigate the relationship between structure and optoelectronic properties. These properties suggest these materials as good candidates as active layer for organic solar cells.
 
An efficient and greener approach has been developed for the synthesis of 6-arylamino-5-cyano-2,3-dihydro-1,3-thiazin-4(1H)-ones, using Lemon juice as a natural catalyst. It was prepared via condensation of 3-arylamino-2-cyano-3-mercaptoacrylamides with several of aldehydes. The reaction proceeded in short period of time with excellent yields. Most of the synthesized compounds were tested in vitro against four bacterial strains, Bacillus thuringiensis, Micrococcus roseus, Escherischia coli and Pseudomonas aeruginosa and two strains of fungi, Aspergillus niger and Penicillium italicum. Biological evaluation of the prepared products showed that many of them revealed promising antimicrobial activity.
 
Corrosion inhibition of welded maraging steel in 1.0 M sulphuric acid was studied in the presence of different concentrations of 2,5-bis (3,4,5-trimethoxy phenyl)-1,3,4-oxadiazole (BTPO) by electrochemical techniques. The results confided that BTPO was a good inhibitor, and the inhibition efficiencies obtained from potentiodynamic polarization and electrochemical impedance methods were in good agreement. The inhibitor, BTPO, acted essentially as a mixed-type inhibitor with its inhibition action through its surface adsorption. The inhibition effciency was found to increase with the increase in BTPO concentration but decreased with the increase in temperature. The activation parameters for the corrosion of the alloy and thermodynamic parameters for the adsorption of BTPO on the alloy surface were calculated and discussed. The adsorption of BTPO on welded maraging steel surface was predominantly through physisorption and obeyed the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) study confirmed the formation of an anticorrosion protective film of BTPO on the metal surface.
 
2-(ethyl xanthate) acetylamino-5-phenyl-1,3,4-thiadiazole, 2-(2-Hydroxybenal) amino-5-phenyl-1,3,4-thiadiazole, 2-(N-cylohexzyl carbamyl methylthiocarbamate)-5-phenyl-1,3,4- thiadiazole, 2-(Allyl) dithiocarbamate-5-phenyl-1,3,4-thiadiazole, dibenzyl-N-(5-phenyl-1,3,4-thiadiazole-2yl)dithiocarbamid, difenacyl-N- (5-phenyl-1,3,4-thiadiazole-2-yl) dithiocarbamid, 1,3-di(dithiocarbamate-5-phenyl-1,3,4-thiadiazole)propane were synthesized. The characterization of all new synthesized compounds was carried out by the 1H-NMR, IR, mass spectroscopic data and elemental analyses. The quantum chemical calculations were obtained by means of the DFT/6-311G(d,p) method.
 
In order to continue our studies in coordination chemistry with pteridine derivatives, ligand pyridinylhdrazone of 6-acetyl-1,3,7-trimetyllumazine (PZLMH) and its mononuclear Cu(II), Ag(I), Cd(II), Hg(II) and Gd(III) complexes have been synthesized. Ligand and metal complexes were characterized by elemental analyses, ¹H- and ¹³C-NMR and IR studies. The result ssuggest that the mononuclear complexes have a metal to ligand mole ratio of 1:1 and the metal ions are coordinated with the phenolic oxygen and imine nitrogen atoms.
 
Corrosion inhibition of mild steel by N-(6-methoxyquinolin-4-yl)-pentane-1,4-diamine (MPD) on mild steel / sulphuric acid solution interface using weight loss, electrochemical impedance spectroscopy (EIS) and polarization studies. The inhibitor showed 99.1% inhibition efficiency at 4×10-4 MMPD concentration. Polarization studies showed that MPD is a mixed type inhibitor. Adsorption of MPD molecules follows Langmuir adsorption isotherm on mild steel surface in sulphuric acid medium. SEM studies supported data evaluated by different techniques by showing the less rough surface in presence of inhibitor than in absence of inhibitor.Contact angle experiments show the hydrophobic nature of mild steel surface with the MPD molecules.
 
Current-potential curves of the CPE/CNF/Poly(1,5-DAN)/NiNPs for electrocatalytic oxidation of methanol at the scan rate of 50 mV.s −1 in 0.1 mol/L NaOH solution with different concentrations of methanol: 0.05 to 1 mol/L. 
A nanocomposite based on a carbon nanofiber/conducting polymers and nickel nanoparticles was developed using cyclic voltammetry. The dispersion, morphology, conductivity and structure of the modified electrode are characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and chronoamperometry (CA). It has been demonstrated that the nanocomposite improves efficiency towards electrocatalytic oxidation of methanol. The saturation limits concentration of methanol to obtain a higher current density is about 0.6 M with a current's stability for more than 2h.
 
The corrosion inhibition of mild steel in 1.0 M HCl solution by Alizarin was investigated using weight loss and electrochemical measurements. The results indicate that the studied compound exhibits good performance as inhibitor for mild steel corrosion in 1.0 M HCl solution and its inhibition efficiency increased with concentration to reach a maximum of 91 % at 10⁻³ M (optimum concentration). The potentiodynamic polarization curves showed that Alizarin acts as a cathodic type inhibitor. It is found also that the inhibition efficiency of this compound decreased with temperature to reach a minimum of 54.3 % at 10⁻³ M at 328 K. In the other, it is shown that the inhibition efficiency increased with immersion time until 4 h to get 0.89 % and decreased after this time to attain 66.1% at 12 h at the optimum concentration. So, the adsorption of Alizarin obeys to the Langmuir adsorption isotherm. In addition, the apparent activation energy, enthalpy, entropy and the free energy were determined and discussed. Finally, the quantum chemical parameters were determined using density functional theory (DFT) method to correlate the calculated structural and electronic parameters of Alizarin with its corrosion inhibition efficiency. The obtained results indicated a good agreement between experimental and theoretical studies.
 
Extract of grapefruit rind (GFR) and grapefruit leaves (GFL) was investigated as corrosion eco-friendly inhibitor of carbon steel in 1.0 M HCl acid using a conventional weight loss measurements, electrochemical technique as potentiodynamic polarization methods and electrochemical impedance spectroscopy (EIS) techniques. The electrochemical polarization data revealed the mixed mode of inhibition. The obtained results showed that all the extracts are excellent corrosion inhibitors and their adsorption on the carbon steel surface follows the Langmuir isotherm model in acidic media. The results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the extract is due to the adsorption of active molecules leading to the formation of a protective layer on the surface of carbon steel. The extracts were found to inhibit the corrosion of carbon steel in 1.0 M HCl solutions and the inhibition efficiencies of the extracts follow the trend: GFR > GFL. Some thermodynamic functions of dissolution process were also determined and discussed.
 
Arrhenius plots of mild steel in 1.0 M HCl (a) without and (b) with 10-3 M of PTQ8 An alternative formula of the Arrhenius equation which can determine the activation enthalpy (ΔH * a ) and entropy (ΔS * a ) using the following equation: ) exp( ) exp( * * RT H R S Nh RT i a a corr   
Relation between Ln (i corr / T) and 1000/T at different temperatures In 1.0 M HCl solution, the addition of PTQ8 leads to an increase in the apparent activation energy E a from 37.64 kJ mol-1 to 42.64 kJ mol-1. This result show that the addition of PTQ8 decreases metal dissolution in 1.0 M HCl medium and that it is to the phenomenon of physisorption [33,34]. The positive sign of ΔH * a which is increases from 35.04 kJ mol-1 to 40.04 kJ mol-1 , reflects the endothermic nature of the mild steel dissolution process indicating that the metal dissolution is slow in the presence of inhibitor [35]. The large negative value of ΔS * a which is slightly increases negatively from-75.03 J mol-1 K-1 to-76.82 J mol-1 K-1, implies that there is decrease of the disorder during the transformation of the reactants into complex. [36]
A new organic inhibitor, namely 5-((4-phenyl-4,5-dihydro-1H-tetrazol-1- yl)methyl)quinolin-8-ol, denoted PTQ8 was synthesized and characterized using ¹H and ¹³C NMR spectroscopies. Thus, its corrosion inhibition on mild steel in 1.0 M HCl solution was investigated by weight loss and electrochemical measurements. The experimental results were supported by DFT calculations. The temperature effect on the corrosion behaviour of mild steel in 1.0 M HCl without and with PTQ8 was studied in the temperature range 298-328 K. The results showed that the inhibition efficiency of PTQ8 increases with concentration and decreases with temperatures. The associated activation energy has been determined and discussed. It is found that the adsorption of PTQ8 on the mild steel surface obeys to the Langmuir's adsorption isotherm. It is found also that the theoretical calculations are in good agreement with the experiments results.
 
A new Heterocyclic organic inhibitor, having a triazole ring, linked with the quinoline ring namely 4-amino-1-((8-hydroxyquinolin-5-yl)methyl)-1,2,3-triazole-5-carbonitrile (AHTC) was prepared and identified by the usual methods as ¹H, ¹³C NMR and Elemental analysis. The influence of AHTC on the protection of XC38 steel against corrosion in 1.0 M HCl solution, have been studied using gravimetric and electrochemical measurement. The obtained results showed that its inhibition efficiency increases with concentration and reaches 90 % at 10⁻³ M. In addition, it is found that the AHTC takes its performance at the temperature range of 298-328 K and its adsorption was well described by the Langmuir isotherm at 298 K. On the other hand, the establishing of correlation between the molecular structures of quantum chemistry indices was carried out using the density functional theory (DFT). Laboratory findings are in concordance with DFT results.
 
Corrosion inhibition by 2-phenyl-1, 4-dihydroquinoxaline (PHQ) on carbon steel in 1.0 M HCl is investigated using electrochemical techniques (EIS and Potentiodynamic polarization), SEM and quantum chemical calculation. Inhibition efficiency of 89% is reached with 5×10-3 M of PHQ at 303 K. Potentiodynamic polarization showed that the PHQ behaves as mixed-type inhibitor. The Nyquist plots showed that increasing PHQ concentration, charge-transfer resistance increased and double-layer capacitance decreased, involving increased inhibition efficiency. Adsorption of the inhibitor molecules corresponds to Langmuir adsorption isotherm. Also, the activation thermodynamic parameters of dissolution were calculated and discussed. Theoretical calculations have been used to make the correlation between the effectiveness of inhibition of our studied inhibitor and their molecular structure.
 
Two newly substituted quinoxalines derivatives of 8-hydroxyquinoline, namely 1,4-bis- ((8-hydroxyquinolin-5-yl)-methyl)-6-methylquinoxalin-2,3-(1H,4H)-dione (Q-HNHyQ) and 1,4-bis-((8-hydroxyquinolin-5-yl)-methyl)-quinoxalin-2,3-(1H,4H)-dione (QCH3NHyQ), were synthesized and characterized by ¹H and ¹³C NMR spectroscopy. Their inhibitory performance was investigated against the corrosion of mild steel in 1 M hydrochloric acid medium by various corrosion monitoring techniques, such as weight loss, Tafel polarization and electrochemical impedance spectroscopy (EIS). It was found that the studied compounds exhibit a very good performance as corrosion inhibitors for mild steel corrosion in 1 M HCl. The inhibition efficiencies obtained from all employed methods are in good agreement with each other. It has been determined that the adsorption for the studied inhibitors on mild steel complies with the Langmuir adsorption isotherm at all studied temperatures. Potentiodynamic polarization studies have shown that the studied compounds act as mixed-type inhibitors toward mild steel. Scanning electron microscopy (SEM) was performed and discussed for surface study of uninhibited and inhibited mild steel samples.
 
as shown.
Summary of ANOVA analysis for tensile strength measurements
Stress-strain diagram showing the tensile properties of heat treated 1025 steel at 850 o C The comparison between the properties of the annealed, normalized and age-hardened steels in respect of their ultimate tensile strengths and yield strengths are shown in Figures 4 and 5. 
Ultimate tensile strength of heat treated SAE 1025 steel samples 
Yield strengths of heat treated SAE 1025 steel samples 
The effect of heat treatment at 850°C on the microstructure and mechanical properties of SAE 1025 carbon steel has been studied. Annealing, normalizing and age-hardening heat-treatments at 850°C were used for the experimental work. Hardness tests, tensile tests and metallography were carried out on the heat-treated and control samples. The results were further analyzed using the one-way ANOVA test. Results obtained showed significant differences in the microstructure and mechanical properties of the different heat-treated samples. The hardness profile determined using a Brinell ball indenter showed decrease in hardness of the heat-treated samples when compared with the control. A microstructure of enhanced quality was obtained with normalizing heat-treatment. A higher tensile strength of 313.55MPa was obtained with annealing heat treatment in comparison to age-hardening (212.94MPa), normalizing (167.79MPa) and the control test (269.12MPa). ANOVA test confirmed the results at 90% confidence and further showed that there was significant difference amid the four test conditions.
 
Schéma du photoréacteur utilisé. Les prélèvements effectués de la solution exposée aux rayonnements UV ont été filtrés sur membrane Millipore de type 0,45 μm. Les mesures de l'absorbance ont été effectuées à l'aide d'un spectrophotomètre type JASCO V-630 UV/Visible afin de déterminer les concentrations en colorant. Le taux de dégradation du colorant est ainsi déduit par l'expression suivante : % í µí°“í µí°ší µí°®í µí°± í µí°í µí°ž í µí°éí µí° í µí°«í µí°ší µí°í µí°ší µí°­í µí°¢í µí°¨í µí° § = í µí°‚ í µí¿Ž − í µí°‚ í µí°« . í µí¿í µí¿Ží µí¿Ž í µí°‚ í µí¿Ž
Diagramme des résidus de la réponse.
Comparaison des valeurs calculées et expérimentales de taux de dégradation du colorant RR120.
Caractéristiques du colorant réactif étudié RR120.
Analyse de la variance de la dégradation photocatalytique du RR120.
Experimental design was used to study the main effects and the interaction effects between operational parameters in the photoelimination of azo dye reactive red 120 (RR120). The important parameters which affect the removal efficiency of RR120 are the initial dye concentration, the amount of catalyst and the pH. The parameters have been respectively coded into x1, x2 and x3, and have been investigated between the two levels (-2 and +2). The results show that the application of Response Surface Methodology (RSM) allows describing in a correct manner the influence of these three experimental parameters on the treatment efficacy. The optimal values of the parameters for the maximum performance were determined. The suggested second order model for the degradation efficiency was validated using different statistical approaches. The response surface 3D plots and the contour plots were used to locate the optimal point. The optimum conditions that were obtained for the photoelimination of the RR120 dye were as follows: the initial dye concentration: 20 mg/l, the amount of catalyst: 0.81 g and the pH of the solution: 5.
 
Evaluation of the FT-IR spectrum of TML and the surface product.
FT-IR spectra of pure TML and the surface product formed on 13Cr L80 steel in 15% HCl in the presence of TML.  
TGA curve of metal surface product obtained after immersion of 13Cr L80 steel in 15% HCl acid solution containing TML.  
The influence of different eco-friendly inhibitors on the corrosion behavior of 13Cr L80 steel in 15% HCl solution was experimentally investigated. In the preliminary study, corrosion tests were performed with various oil well steels like13Cr L80, L80, N80 and P110 steels in order to evaluate the comparative corrosion resistance of these metals when exposed to 15% aqueous hydrochloric acid solutions without inhibitors. In this paper the inhibitive action of a selected inhibitor, thiophene methanol (TML) on the corrosion behaviour of 13Cr L80 steel in 15% HCl solution at different levels of concentrations (0-100 mM) was investigated using weight-loss, electrochemical polarization and AC impedance spectroscopic methods and their results were compared. The inhibition efficiency of TML increased almost linearly with its concentration and was found to be maximum (86.79%) at 75 mM and the increase in temperature resulted in the decrease of the inhibitor efficiency (η) and degree of surface coverage (θ). Surface morphology of the corroded sample was analyzed by SEM. FT-IR spectral study and TGA were carried out to characterize the surface products. The result shows that TML is a good inhibitor for 13Cr L80 steel in HCl acid medium. The adsorption of the TML on the 13Cr L80 steel surface obeyed the Langmuir adsorption isotherm. Thermodynamic and activation parameters are discussed.
 
In this work we are interested in the degradation of an azo dye RY17 by heterogeneous photocatalysis. We have studied in the first place, the adsorption of this dye on TiO2-coated non-woven fibres, in order to determine the optimal conditions for the degradation of the dye, the results show that the adsorption equilibrium is reached after 30 min of adsorption and that the Langmuir describes better the adsorption by report to the Freundlich isotherm. Then, we have discussed the influence of some experimental parameters such as the initial dye concentrations, the initial pH of aqueous solution and the addition of H2O2 on the degradation of the solution studied.
 
The environmental quality of M'zar beach, subjected to effluent from a wastewater treatment plant and the proximity of Souss Oued estuary providing agricultural and fertilized compounds, was assessed in two different sites (S1, situated in the south of Oued souss estuary and S2 in the south of M'zar plant submarine emissary outfall) between 2009 and 2011, focusing on metal contamination (Cd, Hg, Pb) in Donax trunculus (Linnaeus, 1758) soft tissues. In addition, associated toxicological effects were assessed using a multibiomarker approach (catalase, acetylcholinestrerase, glutathione S-transferase, Malondialdehyd). D. trunculus from both sites shows different seasonal and spatial biochemical responses and heavy metals bioaccumulation pattern. The clams responded differently to metal contamination with different biomarker responses showing a clear site trend, suggesting different sources and/or magnitudes of contamination. Mercury was a source of oxidative stress in clams of both sites with a significant influence on neurotoxicity and antioxidant defense and enhancement of lipid peroxidation.
 
The map of the sampling zone in the Northwest of Morocco (Mediterranean sea), ST1:M'diq; ST2: Kaa srass.
Moroccan dredge of Callista chione and Acanthocardia tuberculata.
Mean length variation with depth for Acanthocardia tuberculata and Callista chione populations at two station M'diq and Kaa srass in the Northwest of Morocco.
Being a part of the Mediterranean ecosystem, the maritime zone included between M' Diq and Ouad Laou is characterized by a biodiversity which has not hither to been studied, making difficult the implementation of suitable management measures. A study was undertaken to evaluate the existence of depth segregation between Acanthocardia tuberculata and Callista chione adults and juveniles in populations the Northwest of Morocco, on the West part of its Mediterranean facades, and the macrofaunal diversity associated to this two species. Samples were collected from the infra-littoral zone between December 2009 and April 2010 at two sampling stations situated in the M'diq lagoon and Kkaa srass. Sampling was undertaken at increasing depths (one tow per depth), between 0 metres and 20 depth, the tows were performed parallel to the shoreline. The size frequency distribution showed the predominance of smaller individuals (<50 mm) in the intermediate depth area (5-10 m depth) and the prevalence of larger individuals (≥50 mm) at greater depths (15 m depth). The classic numeric descriptors were used for the characterization of the entities fauna and they indicated naturally disturbed habitat, and that the species met in all of the stations resorts are fairly distributed.
 
The Phoracantha semipunctata (Cerambycidae) is a wood-boring pest of the most formidable of Eucalyptus stands. It is considered as a very invasive species. Its proliferation has increased since the last decade. Nowadays it is an ecological disaster longhorn. It causes dramatic damage in many parts of Morocco. This problem requires special care to ensure the preservation of Eucalyptus plantations. The objective of our work is to conduct a study on the annual evaluation of imagos Phoracantha semipunctata in north-eastern Morocco for control purposes. After an overview on Eucalyptus gomphocephala, the characteristics of the stations used in this study as well as the sampling methods and statistics methods are presented. This study was conducted in two different regions, Saidia's coastal area in 2013 and the green curtain Taourirt-Oujda in 2014 by trapping in natural conditions supplemented by monitoring emergence of semi-natural environment imagos using hatchers prepared at the laboratory. The experiments conducted in the field and inside the laboratory helped us to determine the Longhorn development cycle which is a monovoltine species in Saïdia and bivoltine in green curtain Taourirt-Oujda.
 
In Morocco, high-resolution tree-ring records covering the last hundreds years are very scarce, yet essential for understanding the process and pattern of climate change and designing climate model. In this paper, an Atlas Cedar (Cedrus atlantica M.) ringwidth chronology spanning 1796-2011 AD and 1776-2011 AD was developed using standard dendroclimatological methods in two forest sites designed Tafechna and Ouiouane, respectively, at the Middle Atlas Mountains located in Khenifra province, Morocco. Trees in the second site are the oldest and strongly negative relationships were detected between the ring-width chronology and the monthly mean temperatures from june during the previous season to september during the growing season in this site. Based on correlation analysis, the mean temperature from april to july was reconstructed back to 1776 AD using a regression linear model. Therefore, 34% of the variance in temperature is reconstructed by this model. The reconstructed climate records show several alternating periods of high and low temperatures. Many of these hot years have been recorded to coincide with most of the known principal drought years of Morocco. The analysis of spatial correlation with the overall climate data, and comparisons with other temperature reconstructions based on tree rings surrounding areas, revealed that our reconstruction represented a regional variation on a larger scale temperature in the Middle Atlas region. Significant correlation between tree ring and climate is implying the possible influence of North Atlantic Oscillation (NAO) on the local climate. Considering the strong and negative between tree growth and temperature relationship, future warming will likely cause drought which will influence negatively the growth of trees as seen during the recent climate change experienced by Morocco since 1979. However, due to the limit of cedar age, the reconstruction couldn't save the changes to the millennial scale which requires the development in the future of long time series of tree rings in Morocco.
 
This paper is a bibliometric study of the publication patterns of academic and research scientists of Maghreb countries: Algeria, Morocco and Tunisia. The comparative study of the scientific production in the countries of Maghreb is made using Scopus data during the period 1996-2009. Results show that the total scientific production of Tunisia is higher than that of both Morocco and Algeria, even though the population in Tunisia is only one third of that of Morocco and Algeria. Scientometric analysis is furthermore related to the population to each country. The study deals also to introduce the Hirsch index called h-index of the most published authors according to the Scopus database. Ten of the most published authors of each country are listed and their corresponding h-index values were given.
 
The corrosion rate in the presence of a new synthesized quinoxaline derivative namely 3-methyl-1-prop-2-ynylquinoxalin-2(1h)-one and denoted Pr-N-Q=O as mild steel corrosion inhibitor in molar hydrochloric acid, was studied by weight loss method, in the range of temperature from 308 to 353 K. Results obtained revealed that the inhibition efficiency of this compound decreased relatively with increasing temperature and its value reached 80.0% at 353 K at 10-3M. The inhibition was assumed to occur via adsorption of the quinoxaline molecules on metallic surface. Adsorption of Pr-N-Q=O obeyed to Langmuir adsorption isotherm model fit. The apparent activation energies Ea, enthalpy δH* and entropy of activation δS* values provided evidence of the inhibitory effect of Pr-N-Q=O. Furthermore, spontaneity of the adsorption process, through free energy δadsGdeg; values showed a drastic decrease upon temperature increase in the presence Pr-N-Q=O.
 
B3LYP/6-311G(d,p) quantum calculations are performed to optimize geometries and obtain properties depending on the electronic and photovoltaic for some quinoxalinone derivatives. Novel twelve organic donor-ϕ-acceptor dyes (D-ϕ-A), used for dye-sensitized solar cells (DSSC), based on quinoxalin-2(1H)-one were studied by density functional theory (DFT) and time dependant DFT (TDDFT) approaches to shed light on how the ϕ-conjugation order influence the performance of the dyes. The electron acceptor group was 2-cyanoacrylic for all dyes whereas the electron-donor unit varied and the influence was investigated. The theoretical results have shown that TDDFT calculations using the Coulomb attenuating method CAM-B3LYP with the polarized split-valence 6-311G(d,p) basis sets and the polarizable continuum model (PCM) were reasonably capable of predicting the excitation energies, the absorption and the emission spectra of the molecules. The HOMO and LUMO energy levels of these dyes can ensure a positive effect on the process of electron injection and dye regeneration. The trend of the calculated HOMO-LUMO gaps nicely compares with the spectral data. Key parameters in close connection with the short-circuit current density (Jsc), including light-harvesting efficiency (LHE), injection driving force (δGinject) and total reorganization energy (Λtotal) were discussed. In addition, the estimated values of open-circuit photovoltage (Voc) for these dyes were presented. The calculated results of these dyes reveal that the Q4 dye can be used as a potential sensitizer for TiO2 nanocrystalline solar cells due to its best electronic and optical properties and good photovoltaic parameters.
 
In this article, we will present a stereochemical study of 3 types of compounds: The acyclic diesters derived from the diethyl acetamidomalonate 1, the cyclic diesters derived from the diethyl of 3.4-dihydro-5-phényl-2H-pyrrole-2.2-dicarboxylate 2, the methyl esters derived from 3.4-dihydro-2H-pyrrole-2-carboxylate 3. These compounds were prepared during our work and engaged in dipolar-1.3 cycloaddition on different symmetric dipolarophiles [1,2]. In order to characterize and confirm the stereochemistry of these molecules, we used the 1H NMR parameters and DREIDING models.
 
The 1-ethyl-1H-pyrazolo [3, 4-d] pyrimidine-4(5H)-thione (ETPP) has been evaluated as corrosion inhibitor for mild steel in 1M HCl solution by means of potentiodynamic polarization and electrochemical impedance spectroscopic measurements. The obtained results revealed that this compound is a good mixed type inhibitor with cathodic predominance effectiveness. The effect of temperature on the corrosion behavior with the addition of optimal concentration of 10⁻³M was studied in temperature range of 303-343 K. The value of inhibition efficiency decreases slightly with the increasing of temperature. The adsorption of the inhibitor on the mild steel (MS) surface follows the Langmuir adsorption isotherm, indicating monolayer adsorption. The activation parameters indicate the inhibitor is physically adsorbed. The findings concerning the quantum chemical calculation indicate a high feasibility of molecular adsorption of ETPP.
 
The corrosion performance of mild steel in 1 M HCl solution with different concentrations of synthesized 4-chloro-1H-pyrazolo[3,4-d]pyrimidine (CHPP) was investigated by electrochemical measurements. CHPP has significantly inhibited mild steel corrosion in 1 M HCl solution and the inhibition efficiency increased with CHPP concentration. The inhibitor showed more than 87% inhibition efficiency at optimum concentration of 10⁻³ mol L⁻¹. Potentiodynamic polarization results showed that CHPP was a mixed-type inhibitor with predominately anodic effect. The adsorption of CHPP on mild steel surface was strong and followed Langmuir adsorption isotherm. The relationship between molecular structure of this compound and their inhibition efficiency has been investigated by quantum chemical calculations. The electronic properties such as the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energy levels, energy gap (LUMO/HOMO), dipole moment and molecular orbital densities were computed.
 
One pot synthesis of 6-substituted-3,4-dihydro-4-phenylpyrimidin-2(1H)-ones was carried out by the condensation of substituted benzaldehyde, acetophenone and urea/thiourea with a catalytic amount of ZnI2 under microwave irradiation. The compounds synthesized were characterized by their mass and NMR spectral data. The structural and electronic properties of these compounds have been investigated theoretically by performing semi-empirical molecular orbital theory at the level of PM6 of theory and Density Functional theory at the B3LYP/6-31G(d) levels of theory. The optimized structures, relative binding energies, position of HOMO and LUMO of the molecules are obtained. In this paper the synthesis, mass spectral analysis and DFT studies of 12 compounds of this series are being reported.
 
Pyrano [2, 3-d] pyrimidines could be synthesized using Lewis acid ionic liquid Choline chloride. ZnCl2 and triethanolamine as catalyst, as well as aromatic aldehydes, malononitrile and barbituric acid or 2-thiobarbituric acid as substrates. The ionic liquid showed good catalytic activity and reusable performance under mild conditions. The reaction proceeds smoothly under ultrasonic irradiation at 75 °C. This method provides several advantages such as being environmentally friendly, using a simple workup procedure, shorter reaction time and affording good yields.
 
In this work, we present an experimental study of quinoxalin-2-[1H]-one molecule by UV-visible absorption and emission spectroscopy at room temperature in polar solvents. This study is complemented by calculations of conformational, charge distribution, energy properties and electronic transitions positions of the molecule in the ground state using AM1 and ZINDO semi- empirical methods.
 
The corrosion inhibition properties of AA6061 Alloy in presence of 1M Hydrochloric Acid by Schiff base compounds namely N, N'-bis (Salicylidene)-1, 4-Diaminobutane (SDB) and N, N'-bis (3-Methoxy Salicylidene)-1, 4 Diaminobutane (MSDB) as corrosion inhibitors were investigated by weight loss, Potentiodynamic polarization(PDP), electrochemical impedance spectroscopy(EIS) and scanning electron microscopy (SEM). Potentiodynamic polarization study revealed that the two Schiff bases acted as mixed type inhibitors. The change in EIS parameters is indicative of adsorption of Schiff bases on aluminium alloys surface leading to formation of protective layer. The weight loss study showed that the inhibition efficiency of these compounds increases with increase in concentration and vary with solution temperature and immersion time. The results obtained from weight loss method, Tafel extrapolation technique and electrochemical impedance spectroscopy were in good agreement. The various thermodynamic parameters were also calculated to investigate the mechanism of corrosion inhibition. The effect of methoxy group on corrosion efficiency was observed from the results obtained between SDB and MSDB. The effectiveness of these inhibitors were in the order of MSDB>SDB. The adsorption of Schiff bases on AA6061 alloy surface in acid obeyed Langmuir adsorption isotherm. The surface characteristics of inhibited and uninhibited alloy samples were investigated by scanning electron microscopy (SEM).
 
The corrosion inhibition of mild steel in 1M Sulphuric acid using amoxicillin as inhibitor has been investigated by weight loss, Potentiodynamic polarization, electrochemical impedance spectroscopy, Hydrogen permeation and diffuse reflectance spectroscopic measurements. All these techniques reveal that inhibition efficiency increases with an increase in the concentration of inhibitor. Scanning electron microscopy [SEM] was portrayed for uninhibited and inhibited mild steel surfaces to ascertain the adsorption of inhibitor on the metal. Potentiodyanamic polarization studies indicated that inhibitor act as mixed type. Diffuse reflectance spectroscopy and quantum mechanical calculations substantiated the mere adsorption of inhibitor on the mild steel surface which is responsible for corrosion inhibition of steel in 1M Sulphuric acid. The adsorption of the compounds on mild steel surface obeys Langmuir adsorption isotherm.
 
The inhibition of corrosion of carbon steel by camphor in hydrochloric acid (1M HCl) was tested, using electrochemical techniques (impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) and quantum chemical calculations (QCC). Impedance measurements showed that the double-layer capacitance decreased and charge transfer resistance increased with the rise of the inhibitor concentration, which explains the increase in inhibition efficiency. Potentiodynamic polarization techniques reveal that the presence of the inhibitor does not change the mechanism of hydrogen evolution. The effect of temperature on the corrosion behavior of carbon steel in 1 M HCl with and without addition of camphor was studied in the temperature range between 303 and 333 K. Phenomenon of physical adsorption is proposed from the activation parameter obtained. Thermodynamic parameters show that the adsorption process is spontaneous. Quantum chemical calculations using DFT were used to calculate some electronic properties of the molecule in order to ascertain the correlation between the inhibitive effect and the molecular structure of the camphor molecule.
 
Variation of the of Jatropha curcas concentration with %E
Polarisation Jatropha curcas of mild steel in 1M HCl for various concentrations of Jatropha curcas inhibitor
Gravimetric results of the mild steel corrosion with and without addition of inhibitors studied at 308 K after 6 h of immersion in 1 M HCl
Electrochemical parameters for mild steel in 1M HCl at various concentrations of different Jatropha curcas
Impedance parameters for Mild steel in 1M HCl for various Jatropha curcas concentrations
The effects of natural Jatropha curcas oil on the corrosion of steel in molar hydrochloric acid were studied via the measurements of weight loss, electrochemical and EIS polarisation. The results obtained revealed that Jatropha curcas oil reduced the rate of corrosion. The corrosion inhibition efficiency increased with the increase of inhibitor concentration. Potentiodynamic polarisation studies clearly revealed that the presence of the natural Jatropha curcas oil did not alter the mechanism of the hydrogen evolution reaction and acted a mixed inhibitor. The adsorption of Jatropha curcas oil on the steel surface in molar in hydrochloric acid obeys to the Frumkin adsorption isotherm model.
 
Gravimetric method was used to study the temperature effects on carbon steel corrosion in molar HCl solution, in the absence and presence of methanolic extract of Euphorbia Falcata.L (MEEF). The results revealed that the inhibition efficiency of MEEF increased with the inhibitor concentration. The highest inhibiting efficiency reached 96% at 323 K at 3g/L. The adsorption was spontaneous and followed Langmuir adsorption isotherm at all studied temperatures. Thermodynamic data for inhibitor adsorption and carbon steel corrosion lead to suggest the manner of the adsorption of MEEF.
 
Three Schiff's bases (SBs) namely 2-(2-hydroxybenzylidene amino) acetic acid (HBAA), 2-(4-(dimethylamino) benzylidene amino) acetic acid (DMBA), and 2-(2-hydroxy-4-methyxybenzylidene amino) acetic acid (HMBA) were synthesized and their effects on the electrochemical behavior of mild steel in 1 M HCl was investigated using gravimetric measurements, Tafel extrapolation technique, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) methods. Tafel polarization measurements revealed that these Schiff's bases act as mixed-type inhibitors. Among the studied SBs, HMBA exhibited the best inhibition efficiency of 95% at 400 ppm concentration. Some thermodynamic parameters were also determined to investigate the mechanism of adsorption. The results obtained from weight loss and electrochemical methods are in good agreement.
 
Pyrano [2,3,d] pyrimidines derivatives are very important and valuable compounds in the fields of medicine, biological and pharmaceutical. In this context, we study effects and benefits of various green synthetic strategies in the synthesis of pyrano [2,3,d] pyrimidines derivatives. Green chemistry is design, advancement and use of chemical products and systems that minimize or remove the utilization and formation of destructive and toxic materials. It is a universal method that is feasible to all areas of science chemistry. All synthetic processes involve the use of various substances. Unfortunately majority of the chemical reagents and substances are applied in industry and chemistry laboratories are hazardous and toxic compounds which led to environmental damage, through pollution, threats to human health and resource evacuation, we need to develop and utilize more environmentally friendly protocols. Therefore, all prevalent and old approaches clearly give detrimental impacts to the mankind and all living beings. Green strategies open up multitudinous possibilities for performing rapid organic reactions and functional group transformations more effectively. It is quite obvious from the growing number of emerging publications in this area that the possibility to utilize green chemistry technology allows reaction conditions to be accessed that are very important and valuable for organic synthesis. In this review, we study effects and benefits of various green synthetic strategies in the synthesis of pyrano[2,3,d]pyrimidines derivatives. Due to unique benefits of green reactions, new green protocols are being discovered for eco-friendly synthesis of large number of organic, pharmaceutical and natural compounds. As a result, green synthetic reactions are observing a fresh spring.
 
The layered double hydroxide (LDH) is synthesis from seawater. We studied as potential adsorbents of organic pollutant: herbicide 2,4-D. The adsorption tests were carried out in aqueous medium under air atmosphere, taking into account the effect of some experimental factor, ie as the calcination temperature, contact time, pH, ratio adsorbent / adsorbate and charge density. The results show that the calcined LDH possessed a very high adsorption capacity, and that the adsorption kinetics of 2.4-D by calcined LDH is fast (equilibrium is reached after 20 minutes of contact). The adsorption isotherm of 2,4-D by calcined LDH is the type S. This type of isotherm confirms the weak interaction between the solute molecules and the adsorbent.
 
Top-cited authors
Belkheir Hammouti
  • Université Mohammed Premier
Ismail Warad
  • AN-Najah National University
Rachid Salghi
  • University Ibn Zohr - Agadir
Abdelkader Zarrouk
  • Université Mohammed Premier
Saviour A. Umoren
  • King Fahd University of Petroleum and Minerals