Search

4-(prop-2-ynyl)-2H [1,4]-benzothiazin-3(4H)-one (PBO) was synthesized and evaluated on corrosion resistance for mild steel (MS) in1 M HCl environment. The molecular and crystal structure of PBO has been determined by single-crystal X-ray crystallography, Hirshfeld surface (HS) analysis was carried out by using Crystal Explorer 17.5. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques were used to find corrosion rate (CR) and corrosion inhibition efficiency (η) in the presence and absence of PBO. These techniques were supported with energy dispersive X-ray (EDX) and scanning electron microscope (SEM). Molecular Dynamics Simulation (MDS) and Frontier Molecular Orbital (FMO) are realized by means of the Density Functional Theory (DFT) method. The results show that PBO could offer an inhibition efficiency of 92% at 303 K. The type of inhibition mechanism of PBO was mixed-type. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The SEM pictures displayed a metallic substrate covered with a highly compact protective layer covered. The theoretical findings suggested by electronic/atomic computer simulations supported the inhibitive chemicals interfacial adsorption through reactive centres.

The present study focuses on the inhibitive action of 1H, 4H, 5H-pyrazolo[3,4-d]pyrimidine (PPO) as corrosion inhibitor for copper in 3% NaCl solution by electrochemical techniques and gravimetric method. Results indicated that the compound under study exhibited good inhibition activity with a maximum value of 96.5% at 10−3M. The compound was classified as a mixed type inhibitor with an anodic predominance. The protection efficiency was enhanced with increasing the inhibitor concentration and decreased with the increment of temperature. The adsorption of the inhibitor occurred spontaneously and obeyed to Langmuir isotherm. Monte Carlo simulations showed that PPO had a high adsorption energy and possessed the ability to replace pre-adsorbed aggressive species on copper surface and then formed a protective film. PPO was adsorbed in a parallel configuration providing better coverage of the metal surface.

This work presents the synthesis of a new quaternary compound Cu2CoGeS4 (CCGS) thin film for the first time combined with first-principles calculations (DFT, WIEN2k). The synthesis was done via spray ultrasonic of Cu–Co−Ge precursors onto glass substrate followed by high−temperature (500 °C) sulfurization under inert atmosphere (Ar). A near 2:1:1:4 stoichiometry of Cu2CoGeS4 was confirmed from EDX analysis. X−Ray−Diffraction(XRD) analysis confirmed the formation of polycrystalline Cu2CoGeS4 (CCGS) thin film with a tetragonal stannite structure( 1 4 ‾ 2 m ). Raman spectroscopy confirmed the purity of the film and showed the presence of the characteristic predominant peak ( 339 cm − 1 ) of the tetragonal stannite structure. The band structure displayed a direct band−gap. The experimental and theoretical optical band gaps were found to be about 1.75 eV with high absorption-coefficient in the visible region of the solar spectrum. Electrical measurement confirmed the p-type conductivity with a resistivity of 0.89( Ω . cm − 1 ) and a carrier concentration of 4.6 1016 cm−3. These results and the photoresponse measurement make the Cu2CoGeS4 (CCGS) a potential material for solar cell application and will draw the attention to develop this material in several other applications.

Phosphate glasses of the ternary system Bi2O3-Nb2O5-P2O5 were studied in two compositional series, namely xBi2O3-5Nb2O5-(95−x)P2O5 (serie B), with x = 10–17,5 mol% Bi2O3, and 10Bi2O3−xNb2O5-(90−x)P2O5 (serie N), with x = 2,5–15 mol% Nb2O5. Seven homogeneous glassy samples were prepared, and their amorphous structure were confirmed by X-ray diffraction. The dielectric properties such as dielectric constant ( e ′ ) and dielectric loss (tanδ) were determined as a function of temperature ranging from 100 °C to 500 °C at a fixed applied frequency of 16 kHz. Replacing P2O5 by Bi2O3 or Nb2O5 decreases the dielectric parameters in both series. These results are attributed to the increase in the cross-link density and the rigidity of the glass, leading therefore to a decrease of the polarization. The usual increasing behavior of ( e ′ ) and (tanδ) with temperature may be explained by the augmentation of the orientation polarization and the electrical conduction losses values.

In this work we studied the complexation of Zn2+ in dilute and concentrated phosphoric media. The investigation method used is the liquid-liquid extraction. This method allowed us to define the nature of the zinc phosphoric species and to calculate their stability constants. These are the following entities ZnH2PO4+ and ZnHPO4, whose stability constants are respectively equal to 5.83·10−2 and 5.83·10−5. We also studied at pH and analytical concentration of H3PO4 data the effect of concentration on this complexation. In addition, the sharing data show that the chelate extracted in the organic phase is Z n X 2 , ( H X ) 2 - formed according to the reaction: Z n 2 + + 2 ( H X - ) 2 ⇆ Z n X 2 , ( H X ) 2 - + 2 H + of constant Ke = 5.12·10−3, (X = di (2-ethylhexyl) phosphoric).

The ion exchange method chosen in this work is analogous to that of the slopes used in liquid-solid extraction. The exploitation of this method studies the sharing of Cr(VI) between the liquid and solid phase and makes it possible to highlight the predominant surface complexes, four types of complexes are identified. These complexes result from two intrinsic complexing reactions (without H3O+ exchange) and two other reactions by 1H+ and 1OH− exchange. In addition, we examined the order of these complexes which defines the number of iron nuclei bound to chromium. The results found in this case indicate that the complexes are monodentated both in acid medium and in basic medium, the stability constant of these complexes are: logK10 = 1,7; logK11 = −3,3; logK1-1 = 8,34.

Quaternary semiconductor Cu2NiSnS4 (CNTS) has emerged as an ideal material for solar cells and has attracted the attention of researchers. Tetragonal-structured CNTS thin films have been successfully synthesized via sulfurization (500°C, argon + sulfur) of co-electrodeposited Cu-Sn-Ni-S precursors on molybdenum (Mo) substrate. The effects of the Ni2+ molarity on the deposition potential, structure, composition, morphology, and optical bandgap of the CNTS thin film were examined by using cyclic voltammetry, Raman spectroscopy, x-ray diffraction analysis, scanning electron microscopy (SEM), energy-dispersive x-ray (EDX) spectrometry, and ultraviolet–visible (UV–Vis) spectrophotometer. X-ray diffraction and Raman analyses confirmed formation of CNTS with tetragonal structure and average crystallite size of 17 nm to 20 nm. SEM revealed that the films were homogeneous, while EDX confirmed the presence of Cu-Ni-Sn-S, and the bandgap of the CNTS thin films was evaluated to lie in the range of 1.6 eV to 1.8 eV, making CNTS a strong candidate material for use in photovoltaic cells.

Quaternary compound Cu2CoSnS4 (CCTS) is a potential candidate absorber layer in thin film solar cells to produce clean and inexhaustible energy. In this work the Cu2CoSnS4 (CCTS) thin film was synthesized for the first time by co-electrodeposition of Cu–Co–Sn–S precursors on Molybdenum substrate, followed by a high temperature (500 °C) sulfurization under Argon atmosphere. The potential deposition (−0.95 V/SCE) was determined from cyclic voltammetry . The structure, composition and morphology of the CCTS thin film is characterized in detail by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and energy dispersion spectroscopy. The p-type conductivity of CCTS thin film was confirmed using Mott–Schottky analysis and the band gap value was evaluated to be 1.56 eV, which makes CCTS a promising material for solar cell applications.

New Bismuth niobium phosphate glasses having the compositions xBi2O3-(95-x)P2O5-5Nb2O5 with x ranging from 10 to 17.5 mol% were prepared by melting quenching method. The absence of crystalline structure in the prepared phosphate glasses was confined by both X-ray diffraction and Differential Scattering Calorimetry studies. In the other hand, the effect of Bi2O3 on the chemical durability has been investigated and correlated to the structure using Raman spectral investigation. The relation between the structural changes and composition has been studied by the measurement of the density and glass transition temperature Tg. The obtained results show that the glass transition temperature and chemical properties (water-resistant qualities) increase with increasing compositions of bismuth oxide in all the studied glasses. The structure chains is broken into pyrophosphate groups (P2O7)4- and the P-O-P bonds are depolymerised by the incorporation of distorted Bi(6) units through P-O-Bi bonds. These experimental results agree with a closer structure and act in a manner that Bi2O3 enter the glassy matrix as a network former character

CoFe2O4 nanoparticles were prepared by the co-precipitation method, the structural properties were performed using X-Ray Diffraction (DRX) in the goal to prove the success of Cobalt ferrite formation and determine crystal parameters. The size and morphological study were building using Scanning Electron Microscopy (SEM). The magnetic properties were carried using MPMS SQUID device. The CoFe2O4 nanoparticles present a ferromagnetic behavior below their transition temperature and values of 3 µB of total magnetic moment were achieved under magnetic field of 5 T. Based on the full-potential linearized augmented plane wave (FP-LAPW) method, with the generalized gradient and GGA-PBE approximation, the electronic structure and local magnetic moment were calculated. This theoretical study contributed to a better understanding the role of magnetic interaction sin CoFe2O4 spinel ferrites. Moreover, the theoretical magnetic properties of CoFe2O4 show a good agreement with the experimental results obtained.

To investigate Organochlorine (OC) in Moroccan water samples, two different methods of extraction being the solid phase micro extraction (SPME) and the liquid-liquid extraction (LLE) are exploited. The gas chromatography with an electron capture detector (GC-ECD) and the gas chromatography coupled to a mass spectrum (GC-MS) are elaborated. In order to get the best extraction, different process parameters are cheeked and optimized. The relevant results are obtained using a time of unspecific binding properties of 30 minutes’ duration and mode of agitation for 30 min with agitation by a magnetic stirrer and a temperature of 30 °C. In particular, a comparative study between the results of SPME and LLE coupled to (GC-ECD) and (GC-MS), respectively, are given. Concretely, it has been found that the SPME extraction technique is a very useful method to analyze the pesticide residues in water samples controlled by local laboratories.

The influence of fluoride ions on the corrosion behavior of UNS N08904 stainless steel in polluted phosphoric acid solution was investigated using electrochemical measurements and UV–Vis-NIR spectroscopy. The potentiodynamic polarization curves showed that fluoride accelerates the anodic process by increasing the critical and passive current densities, while the transpassive potential modified towards more active values. The EIS exhibited that the interface solution/metal has a passive film character influenced by the fluoride ions addition. In addition, the UV–Vis-NIR spectroscopy of the surface showed that the fluoride ion increases the iron (III) phosphate dissolution, and the metal oxides into the solution. In contrast, the apparitions of large peaks of the maghemite were a proof that the fluoride ion favors the iron oxidation to Fe3+. It is noted also that the fluoride peaks were identified at 2530 nm, 2556 nm, 2613 nm, which can be interpreted as adsorbed fluoride or a metal-F complex formation. On the other hand, the UV–Vis-NIR spectroscopy of the test solutions showed that the nickel was affected but less than iron and chromium. Those results explain the drastic increase of the local corrosion as shown by Scanning Electron Microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX).

Mild steel (MS) is a material frequently used in industry, but it usually suffers from extensive corrosion in the acidic environment. To reduce this processor, we used the quinoxaline molecule substituted (6-methyl-2-(p-tolyl)-1,4-dihydroquinoxaline ((CH3)2Q) with electron donor group. Corrosion inhibition potency of CH3)2Q on MS in 1 M HCl was first evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. The effect of (CH3)2Q over the MS surface was analyzed by scanning electron microscope (SEM). The parameters of adsorption of the (CH3)2Q on the MS surface are determined. To better understanding of corrosion inhibition mechanisms, theoretical investigations were carried out namely the DFT, molecular dynamics simulations (MDS), radial distribution function (RDF) and mean square displacement (MSD). The outcomes of our investigation spurred us to deduce that (CH3)2Q behave as effective inhibitor for MS corrosion in 1 M HCl at all tested concentrations, the efficiency of the inhibition reaches a maximum value which equals 93.50% at 10-3 M. The type of inhibition mechanism for (CH3)2Q was mixed-type. A CPEn, Q determined by fit and graphical methods plotted by synthetic data, was utilized. The EIS findings revealed that the addition of (CH3)2Q to the corrosive medium leads to a decrease of the charge capacitance resulting in a systematic improve of the interface charge/discharge function and forms an adsorbed layer over the metal surface. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The effect of (CH3)2Q over the MS surface was analyzed by scanning electron microscope (SEM). The parameters of adsorption of the (CH3)2Q on the MS surface are determined. The results show that (CH3)2Q could offer an inhibition efficiency of 93.50 and 77.35% at 303 and 333 K, respectively. The local reactivity and distribution of the electronic density of HOMO/ LUMO shows that the molecules analyzed contain highly reactive centers distributed throughout the molecular structure. New insights were contributed by diffusion model and RDF method.

Essential oil from aerial parts of Artemisia herba-alba from Morocco was hydrodistilled and its chemical composition oil was investigated by capillary GC and GC/MS. The major components were 1,8-cineole (35.6%) and camphor (24.1%). Artemisia herba-alba essential oil AHAO was tested as corrosion inhibitor of stainless steel (SS) in 1M H3PO4 using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy measurements (EIS) and scanning electronically microscopy (SEM) studies. The results obtained showed that the essential oil of Artemisia reduces the corrosion rate. Tafel polarization method indicates that the plant extract behaves as a mixed type inhibitor. The inhibition efficiency increased with inhibitor concentration to attain 88% at 1 g.L−1 of oil at 298 K. Nyquist diagrams obtained from impedance studies provide results confirming the anti-corrosion effect of the studied plant. The temperature effect on the corrosion behavior of (SS) in 1M H3PO4 without and with AHAO at 1 g.L−1 was studied in the temperature range from 298 to 353 K. Thermodynamic parameters suggested that the adsorption is spontaneous and exothermic process and support physical adsorption mechanism. The experimental data fits well into the Langmuir adsorption isotherm model. SEM/EDS studies provide the confirmatory evidence for the protection of (SS) by the green inhibitor. The results obtained from these methods used are in good agreement. Keywords: Artemisia herba-alba, Essential oil, Corrosion, Inhibition, Stainless steel, Adsorption

Nickel- aluminium bronze (NAB) is one of the well-known copper-based alloys; it is a well-recognized material in the marine environment thanks to its good corrosion and wear resistance along with its high strength. In this paper, the effect of film-forming potential on the electrochemical behavior of NAB alloy in 0.1 M Na2SO4 solution was evaluated. The study of the stability of passive films formed on NAB alloy was investigated using potentiodynamic and potentiostatic polarizations, Mott–Schottky (MS) and electrochemical impedance spectroscopy (EIS) analysis. The compositions of the passive films were determined by scanning electron microscope (SEM), UV–vis–NIR spectroscopy, and X-ray diffraction (XRD). All electrochemical tests revealed that the anodic potentials had a strong influence on passive films formed on NAB alloy. At intermediate frequencies above 450 mVSCE, the corrosion process is controlled by the adsorption/desorption process along with charge transfer and diffusion processes. Mott–Schottky analysis indicated that the donor density is in the range of 1021 cm−3 and increased with an increase in the film-forming potential. Moreover, the SEM analysis showed that the NAB alloy suffered a severe corrosion attack of the copper-rich α phase leading to the retention of the κ phases of the as-cast NAB in the passive films. The passive films were grown on the NAB alloy and displayed n-type semi-conductor behavior, which is entirely predictable from the main Cu and Al oxide in the film.

Removal of new antiviral drug sofosbuvir from aqueous solution by non-modified expanded perlite (E-perlite) using adsorption process was investigated. Perlite is high-grade stone rich on silica utilized as inexpensive natural adsorbent. An experimental combination of Response Surface Methodology (RSM) with Central Composite Design (CCD) was applied to optimize the process parameters effecting the adsorption efficiency where the three used major independent variables are pH, adsorbent mass, and initial concentration of sofosbuvir. The results showed that maximum adsorption was attained at solution pH 6.8, sofosbuvir initial concentration 0.1 mM and E-perlite mass 20 g/L. Adsorption data were exploited by applying the kinetic models pseudo first-order, pseudo second-order, and intra-particle diffusion. The adsorption process corresponded to the Langmuir model while the adsorption kinetics correlated appropriately to the pseudo second-order equation. The morphology and composition of E-perlite were characterized by scanning electron microscopy (SEM/EDS).

In this work and for the first time, a near stoichiometric Cu2MnGeS4 thin film have been synthesized via spray ultrasonic deposition of Cu−Mn−Ge precursors onto glass substrate at 180 °C, with post−sulfurization at 500 °C under Ar-atmosphere. The synthesis onto molybdenum substrate gave only secondary phases. Various characterization techniques were carried out. The results were discussed, completed and compared with the theoretical study (WIEN2k). X−Ray−Diffraction (XRD) and Raman spectroscopy analysis confirmed the formation of wurtz-stannite (orthorhombic) Cu2MnGeS4 (CMGS) structure (Pmn21). The presence of Cu−Mn−Ge−S was confirmed by Energy Dispersive X−ray spectroscopy (EDX). A direct band−gap was confirmed from DFT calculation. The optical band gap was found in the range of 1.6 to 1.72 eV (UV−visible measurement, DFT calculation) with high absorption coefficient ( > 10 4 cm − 1 ) in the visible range of the solar spectrum. The results make Cu2MnGeS4 (CMGS) a promising material for solar cell application.

Cu2NiGeS4 (CNGS) thin film has been obtained for the first time. The synthesis was done via spray ultrasonic deposition of Cu − Ni − Ge precursors (aqueous salt) onto glass substrate (Ts = 180 °C), followed by high-temperature sulfurization under inert atmosphere (500 °C − Ar − S8). X − Ray − Diffraction (XRD) and Raman spectroscopy analysis confirm the formation of polycrystalline Cu2NiGeS4 (CNGS) with tetragonal kesterite ( I 4 - ) structure. A near stoichiometry 2:1:1:4 of Cu − Ni − Ge − S was confirmed by Energy Dispersive X − ray Analysis (EDX). The Hall Effect measurement reveals the p − type semiconductor of Cu2NiGeS4 thin film. The theoretical calculation based on the density functional theory (DFT) shows a direct band gap (band structure). The experimental and theoretical optical band gap found to be in the range of 1.60–1.8 eV with high absorption coefficient ( > 10 4 c m - 1 ) in the visible spectra. The obtained results will be a basis to develop these materials in the field of photovoltaics.

Thin film of Cu2FeGeS4 (CFGS) has been obtained for the first time via spray ultrasonic deposition of Cu − Fe − Ge precursors (aqueous salt) onto glass substrate (Ts = 180 °C), followed by sulfurisation under inert atmosphere (500 °C − Argon+sulfur). X − Ray − Diffraction (XRD) and Raman spectroscopy analysis confirmed the formation of polycrystalline Cu2FeGeS4 (CFGS) with tetragonal structure. The presence of Cu − Fe − Ge − S was confirmed by Energy Dispersive X − ray Analysis (EDX). The p − type conductivity was confirmed. The theoretical calculation based on the density functional theory (DFT) show a direct band gap. The experimental and theoretical optical band gap was found to be in the range of 1.72–1.8 eV with high absorption coefficient ( > 10 4 c m - 1 ) in the visible spectra. The obtained results will be a basis to develop this material in the field of photovoltaics.

The effect of fluoride ions on cast iron corrosion resistance in polluted phosphoric acid using electrochemical measurements, UV–Vis–NIR spectroscopy equipped with the integrating sphere, and scanning electron microscopy (SEM) was investigated. Electrochemical measurements revealed that the fluoride ions favor the anodic dissolution, and catalytically enhance the dissolution processes by changing the reaction mechanisms, leads to growing less stable oxide film on the metal surface. Moreover, the UV–Vis–NIR spectroscopy showed that fluoride prohibits the iron and chromium to enrich the material surface. Finally, the SEM analysis proved that the austenitic matrix is the weakest matrix.

The inhibition efficiency (IE) of 4-hydroxy-8-isocyano-9-phenyl-3-(p-tolyl)-1,2-dihydropyrimido[2,1-c][1,2,4]triazepine-5,7-dione (TRC-H) and 9-(4-chlorophenyl)-4-hydroxy-8-isocyano-3-(p-tolyl)-1,2-dihydropyrimido[2,1-c][1,2,4]triazepine-5,7-dione (TRC-Cl) on the mild steel (MS) corrosion in 1 M HCl acid was studied by weight loss, electrochemical (EIS and PDP) techniques, DFT, molecular dynamic (MD) simulations, radial distribution function (RDF) and mean square displacement (MSD). TRC-H and TRC-Cl effect on the surface of MS has even been accentuated by scanning electron microscopy (SEM) and UV–visible. The adsorption on the steel is made according to the Langmuir model. Molecular dynamics simulation (MD) and Density Functional calculations were done to discussing their agreement with previously experimented results.

In this study, new phosphate glasses, having as chemical composition, xBiPO4-(90-x)P2O5-10NbOPO4 (10 ≤ x ≤ 35 mol%), labeled BNPx, were prepared by quenching method and examined by: X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FT-IR) and Raman spectroscopy. Structural analysis showed that adding Bi2O3 lead to the appearance of pyrophosphate (P2O72−) units and to the formation of POBo bonds. The goal of the current study is to investigate the corrosion inhibition of mild steel by BNPx in HCl, using electrochemical analysis. The results exhibit that the studied phosphate glasses, in HCl medium, has a great scope of corrosion inhibitor which depend on the amount of Bi2O3. Diffuse Reflectance Spectroscopy (DRS) measurements confirmed the adsorption of inhibitor glasses on the surface of mild steel. Besides, an analysis of steel surface morphology was elicited using optical microscopy in the presence of BNP35 at 250 ppm.

Quaternary compound Cu2CoSnS4 (CCTS) is a potential candidate absorber layer in thin film solar cells. In this work the Cu2CoSnS4 (CCTS) thin film was synthesized by co-electrodeposition of Cu-Co-Sn-S precursors on Molybdenum substrate, followed by a high temperature (500 °C) sulfurization under Argon atmosphere. The effect of the electrodeposition time of CCTS precursors (Cu, Sn, Co, S) on the crystallographic structure, morphology, composition and optical band gap of CCTS thin films was investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and energy dispersion spectroscopy. From the results, it was found that the properties of the sample can be improved by decreasing the deposition time and we have found that as the deposition time increases, the amount of the secondary phase Cu2-xS increases. The elemental composition is enriched in Co and S and depleted in Cu with increasing time. The band gap was determined from diffuse reflectance and found for all films in the range of 1.4–1.5 eV.