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Nichel-Phosphorus (Ni-P) coatings are deposited on mild steel by using an electroless plating process. The effect of three calix[4]arene derivatives, namely tetra methyl ester-P-tertbutyl calix[4]arene (Calix1), tetra acid-P-tertbutyl calix[4]arene (Calix2) and tetra methyl P-tert-butyl-thicalix[4]arene ester (Calix3) on the deposition rate, the deposit composition, and the morphological surface was investigated and the study of growth mechanisms has delivered useful information about the surface properties of deposit. It is found that these additives modify the deposition rate and the nickel crystallization process. In fact, the Calix1 and Calix3 act as an accelerator, while Calix2 acts as an inhibitor for the nickel electroless. Furthermore, it is shown that the chemical bath is more stable with calix[4]arene derivatives addition and the obtained deposits are compact and adherent. It is observed also that the nickel content increases with additives. On the other hand, the X-ray diffraction showed that the orientation peaks are intensified at {111} in the presence of Calix2, confirming obtained results of EDAX spectrum. The cyclic voltammetry revealed that the tested additives strongly influence the cathodic process and slightly affect the hypophosphite oxidation. Finally, it is found that these compounds improve the anticorrosion efficiency of Ni-P coating on the mild steel substrate in 3%(mass) NaCl, where its polarization resistance increases with Calix2 and Calix3 addition.

This study concerns the analysis of the physico-chemical parameters (T°, pH, EC, NO3-, Cl-, PO43-, HCO3-, SO42-, Ca2+, Mg2+, K+ and Na+) of groundwater from the Doukkala, in order to establish its pollution diagnosis. Thus, water samples were taken at 8 stations in January and July.The results show that the wells are characterized by a geochemical facies Chloride and sulphate of calcium and magnesiu and potassium chloride or sodium sulphate. According to Moroccan standards and the values of certain parameters such as temperature, hydrogen potential, conductivity, alkalis, alkaline earth metals, sulphates, chlorides the studied the ground water was classified from good to poor quality (CNS, 1994).

A pumping station located in the Moulouya River in Morocco, Northern Africa suffered from extensive corrosion damage. Therefore, in this paper, the inhibition efficiency of Cetamine (CE) for mild steel exposed in water of Moulouya River was examined. This study was performed using electrochemical measurements and surface analysis. The results of potentiodynamic polarization measurements indicated that the CE compound classifies as a cathodic inhibitor type for 500 and 700 ppm, while it acts as a mixed inhibitor type at 1000 ppm CE. It is obtained also that the inhibition efficiency increases with CE concentrations to reach an optimum value of 98% at 1000 ppm CE. In addition, the impedance spectroscopy measurements indicated that this behavior can be explained by the formation of a protective film on the electrode surface. However, this study showed that the CE product takes its performance against aggressive water under various conditions (high Cl− concentration ions, electrode rotation rate, temperature, and immersion time).

In this investigation, attempts have been made to study the corrosion inhibition properties of three new triazepine carboxylate compounds for mild steel in 1.0 M hydrochloric acid medium. The evaluation was carried out using mass loss, electrochemical impedance spectroscopy and polarization curves measurement. Impedance diagrams and Bode plots for uninhibited and inhibited systems were analyzed using Zview program. The fitted data observed trails in nearly the same pattern as the experimental results. It is showed that triazepine carboxylate compounds are very good inhibitors for mild steel corrosion in 1.0 M hydrochloric acid medium which act as mixed-type inhibitors. So, the inhibition efficiency was increased with inhibitor concentration in the order Cl–Me–CN > Me–CN > Cl–Me–CO2Et which depended on their molecular structures. Electrochemical impedance spectroscopy showed that all compounds act by the formation of a protective film at the metal surface. Surface analyses via SEM and Optical 3D profilometry were used to investigate the morphology of the steels before and after immersion in 1.0 M HCl solution containing inhibitors. The correspondence between inhibition property and molecular structure of the triazepine carboxylate compounds was investigated, using density functional theory (DFT). Experimental and DFT study was further supported by molecular dynamic simulations study.

In this investigation, attempts have been made to study the corrosion inhibition properties of three new 2-phenyl-4(3H)-quinazolinone-substituted compounds for mild steel in 1.0 M hydrochloric acid medium. The evaluation was carried out using mass loss, electrochemical impedance spectroscopy, and polarization curves measurement. It is shown that 2-phenyl-4(3H)-quinazolinone-substituted compounds are very good inhibitor’s for mild steel corrosion in 1.0 M hydrochloric acid medium, which acts as mixed-type inhibitors. So, the inhibition efficiency was increased with inhibitor concentration in the order Q-p-Cl > Q-m-Cl > Q-H, which depends on their molecular structures and the chloride para/metapositions. Electrochemical impedance spectroscopy has shown that all compounds act by the formation of a protective film at the metal surface. The correspondence between inhibition property and molecular structure of the 2-phenyl-4(3H)-quinazolinone-substituted compounds is investigated, using density functional theory (DFT) . The effect of molecular structure on the inhibition efficiency has been explored by quantum chemical computations and obvious correlations were observed. The binding energies of tested compounds on Fe(110) surfaces were calculated using molecular dynamics simulation. Experimental and DFT study was further supported by molecular dynamic (MD) simulations study.

This chapter studies the operational parameters effects, such as immersion time, corrosion products, and pH, on the inhibition efficiency against corrosion for low carbon steel in simulated cooling water system of the mixture 1 (10-3 M 3-MPOX + 20 ppm CTAB), which corresponds to the best inhibition efficiency. The results show that the corrosion inhibition performance of the studied mixture reinforces with immersion time and has a maximum in the pH range 6.5–7.5. In addition, the analysis of the results shows that there is a dependence of the pH value of the solution and the corrosion current density (icorr). Indeed, a correlation can be established between log (icorr) and the pH using the polynomial equation. Finally, the mixture 1 provides good protection for the attack materials. These studies were evaluated from the polarization curves (PP), electrochemical impedance spectroscopy (EIS).

In this study, scale inhibition performance Trisodium citrate (TSC) was studied using static scale inhibition method, and its corrosion inhibition performance was also investigated by weight loss method and electrochemical measurement. Result showed that TSC could form a layer of corrosion and scale produTSC on mild steel surface in synthetic cooling water. Its inhibition increases with concentration and reaches a maximum of 89% and 95% at 10-3 M for corrosion and scale, respectively. It is noted that TSC takes its inhibition at high temperature and act by physic-sorption process. It is found that the TSC obey to the Langmuir isotherm. Scanning electron microscopy (SEM) showed that TSC inhibits the scale and corrosion by the formation of a protective layer on the mild steel surface.

Objective: In this study, electrochemical measurements were used to characterize Anhydrous Tricalcium Phosphate (ATP) as a corrosion inhibitor for mild steel in 1.0 M HCl. Method: The potentiodynamic polarization curves indicated that the ATP reacts as an anodic type inhibitor. In addition, it has been found that the electrochemical impedance confirms the inhibitor character of ATP obtained by the potentiodynamic polarization curves where the inhibition efficiency increases by its concentration to reach a maximum of 93.79 % at 10-4 M. The temperature solution influence indicated that the corrosion rate increases with temperature while the inhibitor acts actively. Thermodynamic adsorption and activation parameters indicated that the ATP acts by physical adsorption on the metallic surface with an endothermic process of metal dissolution. Result: Additionally, it was found that the adsorption of ATP molecules obeyed to the Langmuir isotherm. Surface analyses via scanning electron microscopy (SEM) was used to investigate the morphology of mild steel before and after immersion in 1.0 M HCl solution without and with 10-4 M of ATP. It is revealed that the ATP acted by the formation of a protective layer on the mild steel.

Purpose The purpose of this paper is to study the effect of silicon and phosphorus content in steel suitable for galvanizing on its corrosion and inhibitor adsorption processes in steels/cetyltrimethylammonium bromide combined and KI (mixture)/5.0 M hydrochloric acid systems has been studied in relation to the temperature using chemical (weight loss), Tafel polarization, electrochemical impedance spectroscopy (EIS), scanning electronic microscope (SEM) analysis and Optical 3D profilometry characterization. All the methods used are in reasonable agreement. The kinetic and thermodynamic parameters for each steels corrosion and inhibitor adsorption, respectively, were determined and discussed. Results show that the adsorption capacity for Steel Classes A and B are better than Steel Class C surfaces depending on their silicon and phosphorus content. Surface analyses via SEM and Optical 3D profilometry was used to investigate the morphology of the steels before and after immersion in 5.0 M HCl solution containing mixture. Surface analysis revealed improvement of corrosion resistance of Steels Classes A and B in the presence of mixture more than Classes C. It has been determined that the adsorbed protective film on the steels surface heterogeneity markedly depends on steels compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content. Design/methodology/approach The effect of silicon and phosphorus content in Steels Classes A, B and C on its corrosion and inhibitor mixture adsorption processes in 5.0 M HCl solution has been studied by weight loss, potentiodynamic polarization, EIS and surface analysis. Findings The inhibition efficiency of mixture follows the order: (Steel Class A) > (Steel Class B) > Steel Class C) and depends on their compositions in the absence of mixture according on their silicon and phosphorus content, that is, the corrosion rate increases with increasing of the silicon and phosphorus content. A potentiodynamic polarization measurement indicates that the mixture acts as mixed-type inhibitor without changing the mechanism of corrosion process for the three classes of mild steels. Originality/value Corrosion rate mild steels in 5.0 M HCl depends on their compositions in the absence of mixture according to their silicon and phosphorus content, that is, the corrosion rate increases with increasing silicon and phosphorus content. The adsorbed protective film on the steels surface heterogeneity markedly depends on steels class’s compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content.

Three 8-(n-bromo-R-alkoxy) quinoline derivatives with a length of the hydrocarbon chain, namely 8-(2-bromoethoxy) quinoline (QN-C2Br), 8-(3-bromopropoxy) quinoline (QN-C3Br) and 8-(4-bromobutoxy) quinoline (QN-C4Br) were prepared and characterized by proton and carbon NMR spectroscopy (1H NMR and 13C NMR). Thus, to evaluate the effect of these compounds on the mild steel (MS) corrosion inhibition in 1.0 M HCl, electrochemical methods of potentiodynamic polarization curves and electrochemical impedance spectroscopy were used. The potentiodynamic polarization curves showed that the tested products act as an anodic - type inhibitor. Thus, EIS designated that the charge transfer resistance arises from 32.41 Ω cm2 to 705.21 Ω cm2, 783.21 Ω cm2 and 1389.12 Ω cm2 at 10−3 M of QN-C2Br, QN-C3Br and QN-C4Br, respectively. In addition, it is found that the adsorption of three compounds on the MS surface obeys the Langmuir adsorption isotherm equation. It is found also that these products take their inhibition efficiency at high temperature. SEM analysis of the surface and UV-visible spectroscopy of the solution indicates the formation of a protective layer on MS surface and an inhibitor-complex in solution, respectively. Finally, to understand the adsorption properties of the studied 8-(n-bromo-R-alkoxy)quinolone derivatives, density functional theory (DFT) calculations and molecular dynamics (MD) simulation were achieved. These theoretical studies indicated that the anti-corrosion performance of the tested molecules follows the trend: QN-C4Br > QN-C3Br > QN-C2Br. This trend is very compatible with the experimental results.

The effect of 2-(5-methyl-2-nitro-1H-imidazol-1-yl)ethyl benzoate (IMDZ-B) at low concentration on brass corrosion in 0.5 M H2SO4 medium at 298 K, was inspected using current-potential measurement, electrochemical impedance technique, and surface analysis. These techniques indicated that this compound inhibits the corrosion of brass at low concentration, which its inhibition efficiency reaches 91.02% at 10−5 M. In addition, the current-potential curves indicate a large plateau of passivation, where its current density decreases from 1.25 mA cm−2 for a free solution to 0.05 mA cm−2 with the presence of 10−5 M of IMDZ-B. This finding was elucidated by the formation of a film where it becomes compact with the increase of inhibitor concentrations. The influence of the electrolyte temperature and the immersion time was also deliberate and demonstrated that IMDZ-B receipts its inhibition performance at great temperature and improves with immersion time. Indeed, it is obtained that IMDZ-B adsorption obeys the Langmuir isotherm and acts via chemical adsorption. Additionally, the surface morphology and chemical composition of brass were examined via SEM morphology coupled with EDAX analysis at different immersion times and indicated that IMDZ-B reacts by the formation of a protective film at the brass surface and confirms the electrochemical results. Finally, DFT calculations and Molecular dynamics simulations revealed that the IMDZ-B compound contain highly reactive centers distributed on imidazole group, and a strong interaction between their molecules and the brass surface.

The of effect of a new calix[4]arenes additives, namely Tetra methyl ester-P-tertbutyl calix[4]arene (Calix1), Tetra acid-P-tertbutyl cali[4]arene (Calix2) and Tetra methyl ester-P-tertbutyl thicalix[4]arene (Calix3), on deposition rate, deposit composition, structure and morphology of electroless copper plating was investigated. It is found that the additives addition decreased remarkably the deposition rate from 27.6 μm h − 1 to 14 μm h − 1 with a change of the crystallization process of copper. It is also shown the coating is adherent and compact deposit and the bath became more stable. Indeed, the SEM studies revealed that the additives modified the surface morphology of the copper deposits and depended on their molecular structures. In the other, the XRD patter revealed peaks intensified orientation {111} plane in the presence of Calix3, which its structure content sulfur atom, indicating that the obtained deposit has good electrical properties. Finally, the cyclic voltammetry and electrochemical impedance spectroscopy studies revealed that the additives are adsorbed at the electrode surface and decreased the deposition rate such as obtained by gravimetric measurements.

In the present work, a new organic inhibitor, namely (2(-4(chloro phenyl-1H-benzo[d]imidazol)-1-yl)phenyl) methanone (CBIPM), that has an inhibitive effect on the ordinary steel corrosion in 5.0 M HCl has been studied using electrochemical measurements (potentiodynamic polarization and electrochemical impedance spectroscopy). The obtained results showed that the inhibition efficiency increased with concentration and reached 98.6% at 10−3 M. In addition, the CBIPM takes its performance at the temperature range of 298–328 K. The adsorption of the inhibitor on the ordinary steel was well described by the Langmuir isotherm. On the other hand, the establishing of correlation between the molecular structures of quantum chemistry indices was carried out using the density functional theory.

The influence of the extracted cinnamon essential oil (CiO) on the copper corrosion resistance in acidified 3.0 wt% NaCl (pH = 2) medium was investigated by using electrochemical measurements and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDS). So, in order to identify the component of CiO responsible for corrosion inhibition of copper in corrosive solution, the density functional theory (DFT) calculations and molecular dynamics simulation were used. Potentiodynamic polarization showed that the tested natural product acts as cathodic-type inhibitor. Electrochemical impedance spectroscopy indicated that the inhibition efficiency increases with CiO concentrations to get up a maximum value of 89% at 200 ppm. In addition, SEM/EDS analysis in the presence of 200 ppm CiO indicated that copper surface was exempt for all corrosion products, confirming its offered protection. Finally, the major calculated quantum chemical descriptors obtained from DFT calculations indicated that the anticorrosion efficiency responsibility attributes to P8 and P46, with the predominance of P8. In the same, the molecular dynamics simulation indicated that the adsorption energy follows the order: P5 (-61.071 kJ mol−1) > P46 (-58.070 kJ mol−1) > P8 (-42.938 kJ mol−1) on Cu (1 1 1) and P8 (-21.220 kJ mol−1) > P46 (-20.066 kJ mol−1) > P5 (-19.591 kJ mol−1) on CuO2 (1 1 0), suggesting a strong adsorption of P8 on oxide copper (1 1 0) surface and consequently therefore the performance of extracted CiO can be attributed to P8, which is parallel to the copper (1 1 1) surface contrary to other molecules P46 and P5.

The present study provides a new application of the 5-(4-methylpiperazinyl)-methylquinolin-8-ol (MPMQ) as an inhibitor for corrosion of carbon steel (CS) in acidic media (1 M HCl). The inhibition performance of MPMQ was evaluated using various methods including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), surface morphology analysis (SEM), quantum chemical computations (DFT), and Monte Carlo simulations (MC). The obtained results, indicating that the compound as a mixed-type inhibitor significantly reduced the corrosion rate of CS due to the formation of a stable protective film on the metal surface. As confirmed by EIS, SEM and theoretical studies, chemically adsorbed MPMQ molecule is a better corrosion inhibitor with higher corrosion performance of about 95% at room temperature. Langmuir isotherm model is the most acceptable one to describe the MPMQ molecules adsorption on the CS-surface. Finally, the experimental data correlated well with the theoretical study.

The work presented the corrosion inhibition potency of the sodium gluconate and trisodium citrate against the corrosion of low carbon steel and revealed that the TSC can be more preferment than the SG molecule. In addition to experimental investigation of the corrosion inhibition capacity of the SG and TSC molecules, the quantum chemical calculations were performed by B3LYP, B3LYP-GD3BJ and M06HF functionals at three basis sets that are 6-31g(d,p), 6-311g(d,p) and 6-311++g(3df, 2pd) basis sets. The global hardness values revealed that the TSC molecule could be preferable to the SG molecule in using the design of the corrosion inhibitor materials because the SG (2.81 eV) was calculated a harder molecule than the TSC (2.70 eV). Molecular dynamic simulations were performed to investigate metal-inhibitor interactions.

The influence of Sodium Gluconate (SG), cetyltrimethylammonium bromide (CTAB) and their mixture on galvanized steel corrosion in 3.0% NaCl solution was investigated by using electrochemical measurement coupled with scanning electron microscopy (SEM). The polarization measurements indicated that SG, CTAB and their mixture act as cathodic-type inhibitors. Indeed, a synergistic effect was found between SG and CTAB. In fact, the inhibition efficiency of the mixture reached 94% at 10− 3 M of SG with 2.74 × 10− 5 M of CTAB. In addition, this inhibition efficiency improved remarkably with immersion time and temperature. The SEM observations and energy dispersive X-ray (EDX) analysis indicated that the surface homogeneity increases with mixture addition. Finally, the thermodynamic parameters were determined and discussed.

WOS: 000380624500053, The adsorption and corrosion inhibition properties of three piperidine derivatives namely, (1-(5-fluoro-2-(methylthio) pyrimidine-4-yl) piperidine 4 yl) 2,5-dimethoxybenzenesulfonamide (FMPPDBS), (1-(5-fluoro-2-(methylthio) pyrimidine-4-yl) piperidine-4-yl)-4-nitrobenzenesulfonamide (FMPPNBS), (1-(5-fluoro-2-(methylthio) pyrimidine-4-yl) piperidine-4-yl)-3-methoxybenzenesulfonamide (FMPPMBS) on the corrosion of iron were investigated by performing quantum chemical calculations and molecular dynamics simulations. Global reactivity parameters such as E-HOMO, E-LUMO, HOMO-LUMO energy gap (Delta E), chemical hardness, softness, electronegativity, proton affinity, electrophilicity and nucleophilicity have been calculated and discussed. The adsorption behaviors of these piperidine derivatives on Fe(110), Fe(100) and Fe(111) surfaces were investigated using molecular dynamics simulation. The binding energies on metal surface of studied compounds followed the order: FMPPDBS > FMPPMBS> FMPPNBS and this ranking obtained is consistent with the experimental data. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

New compounds derived from quinazolinone namely, 3-methyl-2-(p-tolyl) quinazolin-4(3H)-one (QZ-CH3), 2-(4-hydroxyphenyl)-3-methylquinazolin-4(3H)-one (QZ-OH), 3-methyl-2-(4-nitrophenyl) quinazolin-4(3H)-one (QZ-NO2) and 3-methyl-2-phenylquinazolin-4(3H)-one (QZ-H) were synthesized and characterized by RMN spectroscopy. Their inhibition efficiencies against mild steel corrosion in 1.0 M HCl at 298 K were investigated by using electrochemical methods, surface analysis and UV–visible spectrometry coupled with DFT calculations and Monte Carlo (MC) simulation. It is seen that these four products are good corrosion inhibitors for mild steel in 1.0 M HCl, where their inhibition efficiencies increase with concentration to reach maximum values of 92%, 96%, 82%, and 81% at 10−3 M of QZ-OH, QZ-CH3, QZ-NO2 and QZ-H, respectively. In addition, the influence of the temperature solution ranges from 298 K to 328 K, on the performance of the quinazolinone derivatives indicated that it decreases with temperature solution. The activation and thermodynamic parameters indicated that these products act via chemical adsorption on the metallic surface. This finding was confirmed by surface analysis and UV–visible spectrometry with the formation of a thick protective layer on mild steel surface and the formation inhibitor-complex in solution, respectively. Indeed, it is found that these quinazolinone derivatives adsorb on mild steel surface according to Langmuir adsorption isotherm. Finally, the DFT and MC simulation studies don't correlate with electrochemical measurements and surface analysis.

Imidazolidine-2,4-dione as derivative namely 3-methyl-5,5′-diphenylimidazolidine-2,4-dione (MPIM) used as a corrosion inhibitor for mild (MS) steel in 1 M HCl solution using gravimetric, electrochemical, scanning electron microscopy (SEM) and theoretical calculations. EIS measurements on carbon steel surface samples with and without inhibitor confirmed the inhibiting action of the studied compounds and the results showed increases in inhibition efficiency with the increase in concentration. It gives a maximum inhibition efficiency of 89% at 10−3 M and inhibits corrosion by adsorbing at the carbon steel surface. Polarization (PDP) studies suggest that MPIM behave as mixed inhibitor. The adsorption of MPIM on the surface of the mild steel obeyed the Langmuir isotherm and the value of the standard Gibbs free energy of adsorption ( Δ G a d s ∘ ) is associated with chemisorption mechanism. The surface morphology has been studied using SEM coupled with EDX. In addition, the theoretical results are well consistent with the experimental results.

The purpose of this study was to examine the effect of inhibiting corrosion of two biodegradable newly synthesized compound derivatives of D-glucose for carbon steel in 1 M HCl. These compounds were characterized by infrared (IR), Nuclear magnetic resonance (1H and 13C NMR) and Elementary analysis (EA) spectroscopy. The evaluation of the corrosion inhibiting effect was studied using Usual electrochemical methods, DFT calculations and MD simulations. The morphology of the metal surface was characterized by SEM/EDS. However, the gravimetric solutions were analyzed by ICP-OPS and UV-visible spectrometry. This study has shown that these compounds provide good protection for carbon steel against corrosion inhibition in the 1 M HCl. Analyzes by scanning electron spectroscopy coupled with energy dispersion spectroscopy (SEM/EDS) show that the two inhibitors have been well adsorbed on the metal surface. The theoritical studies are in good agreement with those obtained from Electrochemical methods.

A new 2-(5-methyl-2-Nitro-1H-imidazol-1-yl)ethyl benzoate (IMDZ-B) was synthesized and characterized using elemental analyses, NMR and Fourier transform infra-red (FTIR) techniques. Its effect on brass corrosion in 1.0 M H3PO4 solution was investigated by using electrochemical measurements coupled with X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). The polarization measurements showed that the IMDZ-B acts as a mixed type inhibitor. Indeed, it is found that the IMDZ-B compound is a very good inhibitor, which its inhibition efficiency increases with concentration to reach a maximum of 99.5% at 10−3 M. In addition, the obtained electrochemical parameters from impedance indicated that the IMDZ-B molecules act by adsorption on metallic surface. This adsorption was found to obey Langmuir's adsorption isotherm. However, the temperature effect on the performance of IMDZ-B was also studied. It is found that the IMDZ-B takes its performance at high temperature. In addition, the obtained kinetic and thermodynamic parameters showed that the IMDZ-B molecules act via two adsorption modes, physisorption and chemisorptions, and its process is endothermic and spontaneous. Finally, the XRD and SEM/EDX analyses confirmed the electrochemical obtained results. SEM micrograph of brass surface after 16 h of immersion in 1.0 M H3PO4 solution (a) without and (b) with 10−3 M of IMDZ-B.

The adsorption and corrosion inhibition properties of three triazepines carboxylate substituted compounds, namely, ethyl 4,9-bis(4-chlorophenyl)-8-cyano-3-hydroxy-2,7-dioxo-1,2,5,7-tetrahydropyrido[1,2-b]triazepine-10-carboxylate (2Cl–Et), methyl 4,9-bis(4-chlorophenyl)-8-cyano-3-hydroxy-2,7-dioxo-1,2,5,7-tetrahydropyrido[1,2-b]triazepine-10-carboxylate (2Cl–Me), and ethyl 9-(4-chlorophenyl)-8-cyano-3-hydroxy-2,7-dioxo-4-(p-tolyl)-1,2,5,7-tetrahydropyrido[1,2-b]triazepine-10-carboxylate (Cl–Me–Et) on mild steel corrosion in 1.0 M of hydrochloride acid were investigated by using weight loss, electrochemical, and theoretical investigations. It is found that these compounds act as excellent inhibitors and their inhibition efficiencies follow the order: 2Cl–Me > 2Cl–Et > Cl–Me–Et, and they depend on the type of the substituent. In addition, the possible relations between the experimental and theoretical parameters were discussed. It is found that the theoretical parameters confirmed those obtained by experimental studies. Surface roughness morphology for mild steel before and after hydrochloric acid attack is investigated and discussed using 3D-profilometry images. The scanning electron microscope (SEM) images of the corrosion product confirmed the protection offered by triazepines carboxylate derivatives on the surface of the metal immersed in both media. © 2018, Springer International Publishing AG, part of Springer Nature.

International audience; Three new organic compounds primarily based on 8-hydroxyquinoline have been successfully synthesized and characterized via different spectroscopic methods (FTIR, H-1, and C-13 NMR). The synthesized compounds, namely 5-propoxymethyl-8-hydroxyquinoline (PMHQ), 5-methoxymethyl-8-hydroxyquinoline (MMHQ) and 5-hydroxymethyl-8-hydroxyquinoline (HMHQ), were evaluated as corrosion inhibitors for carbon steel in 1 M HCl solution using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss measurements at 298 K. Electrochemical measurements confirmed that the newly synthesized 5-alkoxymethyl-8-hydroxyquinoline derivatives are mixed type corrosion inhibitors and confirmed maximum protection efficiencies of 94, 89 and 81% for PMHQ, MMHQ, and HMHQ, respectively, at the optimum concentration of 10(-3) M. The EIS spectra confirmed a slightly depressed semi-circle profile with a single time constant in Bode diagrams for the three organic compounds over the whole concentration and temperature ranges studied. The adsorption of PMHQ, MMHQ, and HMHQ on the carbon steel surface followed the Langmuir adsorption isotherm. In addition, the kinetic and thermodynamic parameters for carbon steel corrosion and inhibitor adsorption, respectively, were determined and discussed. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses supported the formation of a protective film on carbon steel in the presence of PMHQ, MMHQ, and HMHQ. Density functional theory calculations (DFT) showed that the effectiveness of the inhibitive actions of the studied compounds correlates well with their electron donating ability, whilst Monte Carlo simulations revealed that the extent and favourability of adsorption of inhibitor molecules on the carbon steel surface establish their corrosion inhibition performances.

Electrochemical behavior of low carbon steel in simulated cooling water system in the absence and presence of oxadiazole derivatives, namely 2,5-bis( n -methylphenyl)-1,3,4-oxadiazole with ( n = 2,3,4), denoted n -MPOX, have been investigated using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The polarizations measurements revealed that the oxadiazole derivatives inhibited both cathodic and anodic reactions. Inhibition efficiency depended on the methyl group position and followed the sequence: 3-MPOX ≥ 4-MPOX > 2-MPOX. In addition, their inhibitions were enhanced by the addition of non-oxidizing biocide CTAB. So, a large plate of passivation was registered in the case of mixture 1 (3-MPOX + CTAB) which reinforced the low carbon steel resistance against pitting corrosion. Scanning electron microscopy (SEM) observations and energy dispersive X-ray (EDX) analysis of the low carbon steel surface illustrate that the surface homogeneity increases in the presence of mixtures and confirmed the inhibitor effect after 2 days of immersion.

This work based on the study of corrosion, scale and microorganism inhibition of low carbon steel in cooling water system by organic compounds (Sodium gluconate (SG) associated with Cetyltrimethylammonium bromide (CTAB)) using electrochemical techniques and SEM/EDX analysis. The polarization curves showed that this formulation acts as mixed-type inhibitor. Its inhibition efficiency was found to enhance with increase of pH, electrode rotation and immersion time due to the formation of the inhibitor film on metallic surface as indicated by electrochemical impedance spectroscopy measurements. However, the formulation takes its performance at high temperature and in the presence of corrosion products. Finally, the SEM/EDX observations confirmed that the formulation was a corrosion, scale, and microorganism inhibitor after 15 days of immersion.

The effect of triazole (TR), 3-amino-1,2,4-triaz- ole(ATA)andcetyltrimethylammoniumbromide(CTAB)on the inhibition of brass corrosion in simulated cooling water system has been studied using electrochemical measure- ments, scanning electron microscopy (SEM) observations andenergydispersiveX-ray(EDX)analysis.Thepotentiody- namic polarization study reveals that these inhibitors inhibit both cathodic and anodic reactions, indicating a mixed-type control of inhibition and their inhibition depend on the nitro- gen number in their structure. It shows that the ATA is the bestinhibitor.TheinterferencebetweenCTABandTRderiv- atives against corrosion has been also studied. So, a large passive current plate is observed directly from the corrosion potentialinthepresenceofformulation.Inaddition,theoper- ationalparameterseffectontheperformanceofthisformula- tion is also investigated. Itshows that its inhibition efficiency increases with pH, immersion time and the presence of cor- rosion products and takes its performance by increasing in temperature. The SEM/EDX data confirm that the formula- tion is a corrosion and scale inhibitor.

The corrosion inhibition of mild steel in a 1.0 M hydrochloric acid solution by 2-(4,5diphenyl- 4,5-dihydro-1h-imidazol-2-yl)-5-methoxyphenol (P1) has been studied in relation to the concentration of the inhibitor, as well as to the temperature, using chemical (weight loss) and electrochemical techniques. All the employed methods were in reasonable agreement. The protection efficiency increased with an increased inhibitor's concentration. The obtained thermodynamic adsorption parameters (ΔG*ads, ΔH*ads, ΔS*ads) indicated that this polymer retarded both cathodic and anodic processes through physical adsorption, and blocked the active corrosion sites. It was also found that this compound obeyed the Langmuir's adsorption isotherm.

Inhibitive performance of 3-methylquinoxaline-2 (1H) -thione denoted (MQ = S) on mild steel corrosion in 1.0 M H3PO4 was investigated using electrochemical measurements. It is revealed that this product acts as an excellent corrosion inhibitor for mild steel in 1.0 M H3PO4 where its inhibition reaches 93% at 5 × 10−4 M and increases with immersion time. Potentiodynamic polarization curves indicated that this compound acts as a mixed-type inhibitor. In addition, the MQ = S has its inhibition at high temperature. It was found that the adsorption of this compound obeyed the Langmuir adsorption isotherm.

New quinoline, namely 5-(ethoxymethyl)-8-quinolinol (M-QN), has been synthesized and characterized by different spectral methods, such as 1H NMR, 13C NMR and IR spectra. Its inhibitive action against the corrosion of carbon steel in 1.0 M hydrochloric acid solution was investigated at different temperatures in the range from 25±2 to 55±2 °C by a series of known techniques, such as weight loss, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and Tafel polarization measurements. The inhibition efficiencies obtained from all employed methods are in good agreement with each other. The obtained results show that M-QN compound is a very good inhibitor with an efficiency of 97.7 % at 10-3 M additive concentration in a 1.0 M HCl solution. The inhibition efficiency increased with an increase of the inhibitor's concentration. Changes in impedance parameters (Rct and Cdl) were indicative of adsorption of the compound (M-QN) on the metal surface, leading to the formation of a protective film. Tafel polarization measurements showed that M-QN inhibitor is of a mixed type. The adsorption of the inhibitor on the surface of carbon steel in a 1.0 M HCl solution was found to obey Langmuir's adsorption isotherm. The kinetic and thermodynamic parameters for carbon steel corrosion and inhibitor adsorption, respectively, were determined and discussed. On the bases of thermodynamic adsorption parameters, comprehensive adsorption (physisorption and chemisorption) for the studied inhibitors on carbon steel surface was suggested.

The corrosion and scale behavior of copper in industrial cooling water system were investigated via electrochemical measurements, ionic chromatography, SEM/EDAX, and X-ray diffraction analyses. It was found that the studied water has a corrosion and scale character. The EDAX and XRD analyses indicated that the major corrosion and scale products were the CuO2 and CaCO3, respectively. In addition, the middle Mueller–Hinton test was also employed to evaluate the development of microorganisms for copper in make-up water solution. It is noted that bacterial colonies appeared after immersion of samples in make-up water, indicating that this water develops bacterial colonization. Finally, the influence of some operating parameters on the corrosion and scale rate was studied. It was shown that the scale rate increases with pH, temperature, and the addition of chloride and sulfide ions. It was also found that the corrosion rate increases with temperature and chloride ions and decreases with pH and immersion time.

A new basic formulation of electroless Cu–P plating using sodium hypophosphite as reducing agent was developed at different concentration of NiSO 4 . So, the effect of temperature solution, pH and immersion time on deposition rate was also investigated. It is found that the deposition rate increases with nickel sulphate concentration and temperature and decreases with immersion time. The cyclic voltammetry study showed that the electroless deposition was controlled by the anodic processes. In addition, the scanning electron microscopy (SEM) observations and energy dispersive X-ray (EDX) analysis were used to characterize Cu–P deposit. Thus, the micrograph showed that coating presents a nodular aspect and is relatively homogeneous. Finally, the corrosion protection of mild steel by this coating in 1.0 M HCl was studied using electrochemical measurements. It is found that the protection increases with NiSO 4 concentration and reaches 92% at 2 g L −1 .

WOS: 000459072300001, The inhibition efficiency of three substituted phenyltetrazole compounds, namely 5-(4-chlorophenyl)-1H-tetrazole (Cl-PT), 5-(4-methoxyphenyl)-1H-tetrazole (MO-PT), and 5-phenyl-1H-tetrazole (PT), for mild steel corrosion in 5.0 M HCl solution was investigated using weight loss measurements and electrochemical study. It is showed that these compounds are good inhibitors for mild steel corrosion in 5.0 M HCl solution which act as cathodic type inhibitors. So, the inhibition efficiency was increased with inhibitor concentration in the order of Cl-PT > MO-PT > PT which depended on their molecular structures. It is found also that these compounds toke its performance at different temperatures range from 298 to 328 K. In addition, the thermodynamic adsorption parameters at different concentrations were investigated and discussed. Finally, it is seen that the inhibition efficiency of the studied compounds increased with immersion time to reach a maximum at 12 h.

The effect of N-N dimethyl formamide (DMF) on deposition rate, deposit composition, structure and morphology of electroless copper deposition obtained from hypophosphite baths was studied. The electrochemical reactions of hypophosphite (oxidation) and cupric ion (reduction) have been investigated at various concentrations of DMF. It is found that the deposition rate decreased significantly with the DMF addition and the deposits' color changed from dark-brown to copper-bright with improved uniformity. Indeed, SEM/EDX analysis showed that the nickel and phosphorus content in the deposits decreased slightly with DMF addition. Cyclic voltammetry and electrochemical impedance spectroscopy showed that the DMF inhibited the oxidation of hypophosphite and the reduction of cupric ions by its adsorption on metallic surface.

2,5-Bis(n-methylphenyl)-1,3,4-oxadiazole with (n = 2,3,4), denoted n-MPOX, have been investigated by using potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) methods, to evaluate the electrochemical behavior of brass in simulated cooling water system. The PP study revealed that oxadiazole inhibited both cathodic and anodic reactions, indicating a mixed type control of inhibition. It was shown that, 3-MPOX as well as 4-MPOX, were the best inhibitors and the inhibition efficiency followed the sequence: 3-MPOX ⩾ 4-MPOX ≫ 2-MPOX. The interference between non-oxidizing biocide CTAB and 3-MPOX and 4-MPOX against corrosion and biocorrosion has also been studied.

The corrosion inhibition of mild steel in 1 M HCl by three substituted quinoxalinones, namely quinoxalin-2(1H)-one (Q1), 6-methylquinoxalin-2(1H)-one (Q2), and 6-nitroquinoxalin-2(1H)-one (Q3), was investigated using density func- tional approach B3LYP/6-31G* calculations. The calculated quantum chemical parameters are the highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (DE), dipole moment (l), electronegativity (v), electron affinity (A), global hardness (g), softness (r), ioni- zation potential (I), fraction of electrons transferred (DN), global electrophilicity (x), polarisability (a), and total energy. All calculations have been performed by considering DFT using the GAUSSIAN03 W suite of programs. The obtained parameters are calculated and discussed.

Corrosion inhibition by 4-amino-1,2,4-triazole, 3-(2-pyridyl)-4-amino-1,2,4- triazole (2-PAT) and 3-(4-pyridyl)-4-amino-1,2,4-triazole (4-PAT) on mild steel in 1 M H3PO4 was investigated by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy measurements. The results indicate that these compounds act as inhibitors retarding the cathodic corrosion reaction. Adsorption of triazoles derivatives on mild steel surface was also studied to examine basic information on the interaction between the inhibitors and the metal surface. It was found that the inhibitors adsorb on the metal surface following the Langmuir isotherm model. In addition, a synergism effect with KI was studied. It was found that the inhibition efficiency of triazole derivatives increases with iodide ions concentration to achieve 97 % at 5 × 10−4 M of KI. The temperature effect on the corrosion behavior of mild steel in 1 M H3PO4 in the absence and presence of 4-PAT with KI (mixture) was studied in the temperature range from 293 to 333 K. It is noted that the mixture retains its performance in this range. Finally, an adsorption mechanism of triazoles molecules with KI has been proposed and is discussed.

The corrosion rates of mild steel in 1 M H2SO4 in the presence of 3-methylquinoxalin-2(1H)-one (Q1) and 3-methylquinoxalin-2(1H)-thione (Q2) were evaluated using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy measurements. It is seen that the inhibition efficiencies increase with concentration of both inhibitors and the Q2 performed excellently as a corrosion inhibitor with its efficiency attaining more than 99 % at 10−3 M. In addition, it is noted that the inhibition efficiency of Q1 decreases while that of Q2 increases with immersion time. On the other hand, there was only a slight effect of temperature on the performance of Q2. The apparent activation energies, enthalpies, and entropies of the dissolution process and the free energies for the adsorption process in the presence of Q2 are determined and are discussed. Adsorption of Q2 on mild steel surface was investigated to consider basic information on the interaction between the inhibitor and the metal surface. It was found to obey the Langmuir adsorption isotherm.

The inhibition behavior of 6-methyl-4,5-dihydropyridazin-3(2H)-one (MDP) on corrosion of mild steel in 1 M HCl and 0.5 M H2SO4 was investigated using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. The results indicated that the corrosion inhibition efficiency depends on concentration, immersion time, solution temperature, and the nature of the acidic solutions. It is also noted that MDP is at its the most efficient in 1 M HCl and least in 0.5 M H2SO4. The effect is more pronounced with MDP concentration. It is found that the inhibition efficiency attains 98 % at 5 × 10−3 M in 1 M HCl and 75 % at 5 × 10−2 in 0.5 M H2SO4. Polarization measurements showed that the MDP acts as a mixed inhibitor. EIS diagrams showed that the adsorption of MDP increases the transfer resistance and decreases the capacitance of the interface metal/solution. From the temperature studies, the activation energies in the presence of MDP were found to be superior to those in uninhibited medium. Finally, a mechanism for the adsorption of MDP was proposed and discussed.

Three quinoxalinone derivatives, namely (E)-3-styrylquinoxalin-2(1H)-one (SQ), (E)-3-(4methoxystyryl)quinoxalin-2(1H)-one (MOSQ) and (E)-3-(4-methoxystyry1)-7-methylquinoxalin-2(1H)-one (MOSMQ) were synthesized and characterized. Thus, their inhibition effects on mild steel corrosion in 1.0 M HCl medium were investigated using weight loss method, electrochemical measurements. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 298-328 K. Polarization measurements indicated that, the studied compounds act as a mixed type inhibitors, the inhibition efficiency depends on their concentrations and followed the order MOSQ> MOSMQ> SQ Electrochemical impedance spectroscopy showed that all compounds act by the formation of a protective film at the metallic surface. The adsorption of three inhibitors on steel surface obeyed Langmuir model, thus the thermodynamic and kinetic parameters were calculated and discussed. In the part based on DFF calculations of this study, some electronic properties of studied molecules were calculated and discussed with the help of B3LYP/6-311G (d,p), B3LYP/6-311 ++G (d,p) and B3LYP/6-311G ++ (2d,2p) methods. The theoretical and experimental results are in good agreement. (C) 2016 Elsevier B.V. All rights.reserved., Three quinoxalinone derivatives, namely (E)-3-styrylquinoxalin-2(1H)- one (SQ), (E)-3- (4-methoxystyryl)quinoxalin-2(1H)- one (MOSQ) and (E)-3- (4-methoxystyryl)- 7-methylquinoxalin-2(1H)- one (MOSMQ) were synthesized and characterized. Thus, theirinhibition effects on mild steel corrosion in 1.0 M HCl medium were investigated using weightloss method, electrochemical measurements. The effect of temperature on the corrosionbehavior of mild steel was studied in the range of 298-328 K. Polarization measurementsindicated that, the studied compounds act as a mixed type inhibitors, the inhibition efficiencydepends on their concentrations and followed the order MOSQ > MOSMQ > SQ.Electrochemical impedance spectroscopy showed that all compounds act by the formation of aprotective film at the metallic surface. The adsorption of three inhibitors on steel surfaceobeyed Langmuir model, thus the thermodynamic and kinetic parameters were calculated anddiscussed. In the part based on DFT calculations of this study, some electronic properties ofstudied molecules were calculated and discussed with the help of B3LYP/6-311G (d,p),B3LYP/6-311++G (d,p) and B3LYP/6-311G++ (2d,2p) methods. The theoretical andexperimental results are in good agreement.

The inhibition action of (E)-7-chloro-3-(4-methoxystyryl)quinoxalin-2(1H)-one (Q1) and 7-chloro-2-(4-methoxyphenyl)thieno(3.2-b)quinoxaline (Q2) have been investigated for mild steel corrosion in 1 M HCl at different temperatures ranges (303–333 K) using potentiodynamic polarization curves. It was found that the studied compounds exhibit a very good performance as corrosion inhibitors for mild steel in 1 M HCl. Results show that the inhibition efficiency increases with decreasing temperature and increasing inhibitors concentration. Thermodynamic parameters such as adsorption heat ( $$ \Updelta H_{\text{ads}}^{*} $$ ), adsorption entropy ( $$ \Updelta S_{\text{ads}}^{*} $$ ) and adsorption free energy ( $$ \Updelta G_{\text{ads}}^{*} $$ ) were obtained from experimental data at temperatures ranging from 303 to 333 K. Other thermodynamic parameters such as E a, $$ \Updelta H_{\text{a}}^{*} $$ , $$ \Updelta S_{\text{a}}^{*} $$ and pre-exponential factor have been calculated and discussed. Adsorption follows the Langmuir isotherm with negative values of free enthalpy suggesting a spontaneous adsorption process.

The inhibition effect of new heterocyclic compounds, namely N-(cyanomethyl)benzamide (BENZA) and N-[(1H-tetrazol-5-yl)methyl]benzamide (BENZA-TET), on mild steel corrosion 1 M HCl was investigated using electrochemical measurements. The results indicated that the inhibition efficiency depends on concentration, immersion time and temperature. The BENZA is a better inhibitor than BENZA-TET. Polarization measurements showed that the inhibitor BENZA-TET is a cathodic type, but BENZA acts as a mixed type inhibitor. In addition, the changes in impedance parameters indicated that these compounds adsorbed on the metal surface leading to the formation of a protective film. Adsorption of benzamide derivatives on the mild steel surface was investigated to consider basic information on the interaction between the inhibitors and the metal surface. It was found to obey the Langmuir adsorption isotherm. From the temperature dependence, the activation energy in the presence of (BENZA) was found to be inferior to that in uninhibited medium. In order to explain why BENZA is the most efficient inhibitor, quantum chemical calculations were applied. The relationships between quantum chemical parameters and corrosion inhibition efficiency have been discussed to see if there is any correlation between them.

7-Cchloro-3-(4-methoxystyryl)quinoxalin-2(1H)-one (CMOSQ) and 7-chloro-2-(4-methoxyphenyl)thieno(3.2-b)quinoxaline (CMOPTQ) have been investigated for mild steel corrosion in 1 M HCl at different concentrations using weight loss measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy methods. Generally, inhibition efficiency of the investigated compounds was found to depend on inhibitor concentration and their structures. Comparitive results showed that CMOPTQ was the best inhibitor and the inhibition efficiency increased with increasing the concentration and attained 86 and 87 % at 10−3 M of CMOPTQ and 10−3 M of CMOSQ, respectively. Potentiodynamic polarization studies clearly reveal that these inhibitors act essentially as cathodic-type inhibitors. The inhibition efficiency increases with immersion time and reaches 95 % CMOPTQ at 24 h. The electrochemical impedance spectroscopy result showed that these compounds act by formation of film.