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International audience; The heterocyclic system, namely 4-phenyl-decahydro-1H-1,5-benzodiazepin-2-one (POBZ) was inspected as a corrosion inhibitor of carbon steel (CS) in a 1 M HCl medium through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements (PDP), and scanning electron microscopy (SEM). The experimental data indicate that the inhibiting action augments with augmenting POBZ amount and reduces with augmenting temperature. The inhibiting action efficiency of 90.98% is obtained with 0.001 M at 303 K. The potentiodynamic polarization (PDP) results mentioned that the POBZ is of mixed type. The adsorption of POBZ on the CS followed Langmuir isotherm. SEM exams affirmed that the steel surface is smooth in presence of POBZ. In light of the calculations of density functional theory (DFT) and molecular dynamics simulation, the mechanism of POBZ inhibitory activity was addressed.

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.

This work is devoted to the study of the inhibition of corrosion of mild steel (MS) in molar hydrochloric acid (1 mol⋅L-1 HCl) by two named quinoxaline derivatives namely, 2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline (HQ) and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline (CQ). The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques (stationary and transient techniques). The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates (ηEIS%) reached up to 91% and 94.2% at 10−3 mol⋅L-1 for HQ and CQ, respectively. The mentioned molecules are classified as mixed-type inhibitors. The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol⋅L-1 medium obeys the Langmuir adsorption isotherm. The results of the scanning electron microscope (SEM) showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied. Elementary analysis is obtained by energy dispersive X-ray spectroscopy (EDS). The inhibition property was further elucidated by theoretical approaches such as: Density Functional Theory (DFT), quantum chemical descriptors (QCD), local reactive indices, solvent effect, theoretical complexation, Molecular Dynamic (MD) simulation, effect of temperature on adsorption energy (Eads), Radial Distribution Function (RDF), and Mean Square Displacement (MSD). The results of these approaches support the experimental results.

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.

The present work aims to examine the link between biodiesel degradation and the corrosion behavior of the 307 L stainless steel used for its storage. Biodiesel was produced from soybean waste cooking oil (SWCO) by trans-esterification process based on a heterogeneous catalyst and methanol. 307 L stainless steel was used to assess the metal surface corrosion after direct contact with the biofuel. The different changes in the biodiesel composition were investigated by FTIR, GS-MS, and UV-absorbance, while the corrosion effect was evaluated by electrochemical methods, SEM/EDS microscopy techniques, X-ray diffraction (XRD) analysis, and UV–Vis–NIR absorbance. The results reveal a weak influence of methyl ester on metal degradation, indicating a low corrosion rate with a localized micro pitting on its surface. Moreover, flame atomic absorption spectroscopy (FAAS) showed the existence of a diminutive number of metal ions, and the electrochemical assays such as electrochemical impedance spectroscopy (EIS) and the polarization curves (PC) exhibited a great corrosion resistance of the 307 L stainless steel by the formation of a passive film.