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In the pickling industry, corrosion can deteriorate the quality of equipment and supplies, causing financial losses and safety threats. Therefore, it has become crucial to develop novel corrosion inhibitors that are bioactive, efficient, affordable, medium-acid soluble, and ecologically safe to protect mild steel during industrial cleaning. In this work, three newly synthesized imidazo[1,2-a]pyridine derivatives were characterized by various spectroscopic techniques. The studied compounds were evaluated as corrosion inhibitors for mild steel in 1 M HCl medium using weight-loss, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. The imidazopyridine derivatives showed excellent anticorrosion performance, their inhibitory efficiencies increased with the increase of inhibitors concentration and evolved in the following order: Imd2 (98.1%) >Imd1 (96.5%) >Imd3 (95.3%). This order was justified by the presence of two chlorine atoms in the ortho position of the Imd2 structure. The three Imd derivatives obeyed to the Langmuir isotherm, this explained the formation of an organic monolayer on the steel surface indicated by the scanning electron microscope (SEM) and the atomic force microscope (AFM). In addition, density functional theory (DFT) and molecular dynamics (MD) simulations were performed to reveal the anticorrosion mechanism. The present study illustrates at the microscopic level how mild steel resists corrosion and ensures the safety of pickling. [ABSTRACT FROM AUTHOR]

In this work, the synergistic inhibition performance of three readily available compounds that 4-dimethylaminopyridine (DMAP), potassium bromide (KBr), and sodium dodecyl sulfonate (SDS), which for the corrosion of mild steel in 1 M HCl solution was investigated by weight loss measurements, electrochemical measurements, surface analysis methods, and molecular simulation technique. The weight loss measurement shows that the ternary corrosion inhibitor still has excellent corrosion inhibition performance at high temperature, and the corrosion inhibition efficiency can be as high as 93%. Potentiodynamic polarization (PDP) results suggested that the mixture belongs to the mixed-type inhibitor which mainly inhibits the anodic reaction. Electrochemical impedance spectroscopy (EIS) measurements demonstrated that a self-assembled barrier film can be formed on the steel surface, which increased the polarization resistance and effectively hindered the corrosion. The efficiency of the mixture corrosion inhibitor reaches 83.6%, which is significantly higher than that of a single corrosion inhibitor. Surface analysis showed that the roughness of the substrate surface decreased due to the adsorption of DMAP-SDS-KBr mixture. The combined Monte Carlo (MC) and molecular dynamics (MD) simulations revealed the synergistic adsorption mechanism, which confirmed the experimental findings. [ABSTRACT FROM AUTHOR]

• DDA shows excellent corrosion inhibition performance for Q235 steel in H 2 SO 4. • The solubility and toxicity of DDA were evaluated by theory. • Surface morphology of Q235 steel was examined by SEM and AFM. • The adsorption process of DDA follows Langmuir adsorption isotherm. • Experimental results were supported by DFT and molecular dynamics calculations. 3,3-Dithiodipropionic acid (DDA) as a potential corrosion inhibitor for Q235 steel in 0.5 M H 2 SO 4 solution was examined. A variety of research approaches including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), atomic force microscopy (AFM), and computational techniques were employed. The toxicity and solubility of DAA were reasonably assessed. Its inhibition efficiency can reach approximately 93% when the optimal concentration is 5 mM. The results of PDP curves manifest that DDA is a mixed type corrosion inhibitor. EIS data indicate that the charge transfer resistance increases with increasing concentration of DDA. Gibbs free energy obtained from the Langmuir isotherm model suggests that DDA molecules hinder the acid attack mainly by chemisorption. Surface topography analysis strongly confirmed the electrochemical findings. Moreover, the simulation results based on density functional theory (DFT) calculation and molecular dynamics (MD) simulations supported the successful interfacial adsorption of DDA on Fe(1 1 0) surface. [ABSTRACT FROM AUTHOR]

• Corrosion inhibition of mild steel in 1 M HCl by N, S-CDs was investigated. • Inhibition efficiencies were experimentally achieved by EIS and PDP techniques. • Surface characterizations have been performed by SEM, AFM, and CAM tests. • The adsorption behavior was demonstrated by XPS. Novel N, S co-doped carbon dots (N, S-CDs) with memory effect were prepared by hydrothermal method using citric acid and l -cysteine as precursors. Structural and morphological characterizations confirmed that N, S-CDs are carbon dots with multifunctional groups and excellent water solubility. Electrochemical measurements indicated that N, S-CDs can effectively inhibit the charge transfer in the corrosion process of steel, and the inhibition efficiency is nearly 90%. The obtained N, S-CDs exhibits outstanding inhibition performance for steel corrosion, which offers a new thought for exploring environmentally friendly corrosion inhibitors. [ABSTRACT FROM AUTHOR]

An ab initio density functional theory (DFT) calculation revealed the electronic properties of azomethine functionalised epoxy, namely, 4-((oxiran-2-yl)methoxy)-N-(4-(4-(4-((oxiran-2-yl)methoxy)benzylideneamino)phenoxy)benzylidene)benzenamine (DSBE) and amine based curing agent namely diethylenetriamine (DETA), triethylenetetraamine (TETA) and para-phenylenediamine (PPD) responsible for its adsorption on the mild steel surface. The frontiers molecular orbitals (FMOs) and the corresponding energies as well as global softness values revealed the reactive nature of the studied organic molecules. The probable trends of the chemical properties of different amine cured epoxy have been predicted. The insights of the adsorption of these organic molecules have been visualized through density functional tight binding calculation. It revealed that these organic molecules are able to adsorb onto targeted metal surface viz. Fe(110), FeO(110) and Fe2O3(110) plane through charge density sharing occurring at the molecule-iron layer interface. Thus, a complete theoretical insight analysis and modelled simulated adsorption study provided a clear picture regarding the adsorptions of the organic molecules onto metallic surfaces. [ABSTRACT FROM AUTHOR]

• An eco-friendly drug losartan potassium (LP) is developed as a superior mixed-type inhibitor for steel corrosion. • The multi-anchored film of LP is formed on steel substrate. • Theoretical modelling provides deep insights into the inhibition performance of LP. The present study aimed to find a suitable alternative for traditional and hazardous corrosion inhibitors. A green antihypertensive drug-Losartan potassium (LP) with superior corrosion protection ability was developed for the first time. Gravimetric method, potentiodynamic polarization, AC impedance, and scanning vibrating electrode technique (SVET) were combined to evaluate the corresponding inhibition performance towards Q235 steel in HCl medium. The results indicated that LP exhibited superior mixed-type corrosion protection to steel at different temperatures owing to the formation of compact and ordered LP-adsorption film on steel surface. Specifically, the inhibition performance values increased to 88.9%, 91.8%, and 92.0% for 5 mM LP at 298, 308, and 318 K, respectively. Meanwhile, N-Fe bond from X-ray photoelectronic spectroscopy (XPS) implied multiple anchoring interaction between steel and LP with nitrogen atoms as active sites. Based on DFT calculation and molecular dynamics (MD) simulation, the obtained low energy gap (Δ E) and high E binding values as well as radial distribution function (RDF) analysis represented strong chemisorption of LP on Fe substrate, which theoretically explained the favorable inhibition effectiveness of LP compound at molecular or atomic level. [ABSTRACT FROM AUTHOR]

Corrosion has caused serious damage to our society, lives and environments. Although the corrosion of metals and their alloys was inevitable, it was controllable using the certain protection method. Using corrosion inhibitors was a feasible strategy to protect metals and alloys from corrosion. Traditional inorganic and organic inhibitors were toxic and expensive. Growing ecological awareness and economic challenges prompted people to look for cheap, efficient, safe and nontoxic green corrosion inhibitors. In this review, the related researches of nitrogen-containing heterocyclic compounds (NCHCs) and carbon dots (CDs) as green corrosion inhibitors were summarized. The chemical compositions of several nitrogen-containing heterocyclic compounds (NCHCs) and carbon dots (CDs) and their corrosion inhibition efficiency in aggressive solutions are reviewed. The corrosion inhibition mechanisms of these environmental friendly corrosion inhibitors on metal surfaces were discussed in detail. This review briefly introduced the corrosion determination method, and expounded the application of surface analysis technology and computational chemistry tools in understanding the anti-corrosion mechanism of green and efficient corrosion inhibitors. [ABSTRACT FROM AUTHOR]

In the present work, essential oil of Calamintha (EOC) was extracted from Calamintha plant and characterized by gas chromatography-mass spectrometry (GC-MS) and FTIR technique. In addition, EOC was evaluated as an ecological corrosion inhibitor of mild steel in 1 M HCl medium by various electrochemical techniques. Satisfactory consistency was obtained between the gravimetric method, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The maximum efficiency was recorded for the concentration of 1.5 g/L EOC which reached 87.57%. However, the morphology of the metal surface analyzed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed the appearance of a protective barrier on the steel surface. Finally, a theoretical study was carried out on the basis of the density functional theory (DFT) and molecular dynamics (MD) simulation technique. [ABSTRACT FROM AUTHOR]

Due to environmental awarenesses and strict restrictions, industries are forced to bring their processes closer to the considered eco-friendly standards. Without a doubt, corrosion is the most obvious problem in industries and inhibitors are among the most applicable materials for metals' corrosion retardation. For this reason, extensive studies have been conducted in the field of green corrosion inhibitors in recent years. The present work concentrated on the evaluation of the bio-molecules from Mint leaves extract on the steel corrosion mitigation in HCl solution. The Mint extract (ME) structures were investigated by FTIR, UV-Vis, and Raman spectroscopies. It was shown by a polarization experiment that Mint extract at 800 ppm caused the current density (i corr) reduction from 1.03 mA/cm2 (for the blank sample) to 0.11 mA/cm2 which was aided by a mixed inhibition (cathodic – anodic) mechanism. The EIS results illustrated that at the optimum condition around 91 % inhibition degree was reached after introducing 800 ppm Mint extract. The weight loss investigations, however, affirmed that a 92 % efficiency was achievable at 25 °C, which was mitigated to 89 % at 55 °C. Eventually, the thermodynamic and adsorption isotherm records represented that Mint extract molecules mono-layer was constructed by utilizing the exothermic interactions. Via the MD and DFT simulations, the interfacial interactions and corrosion inhibitors' adsorption mechanism over the steel surface was exhibited. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to environmental awarenesses and strict restrictions, industries are forced to bring their processes closer to the considered eco-friendly standards. Without a doubt, corrosion is the most obvious problem in industries and inhibitors are among the most applicable materials for metals' corrosion retardation. For this reason, extensive studies have been conducted in the field of green corrosion inhibitors in recent years. The present work concentrated on the evaluation of the bio-molecules from Mint leaves extract on the steel corrosion mitigation in HCl solution. The Mint extract (ME) structures were investigated by FTIR, UV-Vis, and Raman spectroscopies. It was shown by a polarization experiment that Mint extract at 800 ppm caused the current density (i corr) reduction from 1.03 mA/cm2 (for the blank sample) to 0.11 mA/cm2 which was aided by a mixed inhibition (cathodic – anodic) mechanism. The EIS results illustrated that at the optimum condition around 91 % inhibition degree was reached after introducing 800 ppm Mint extract. The weight loss investigations, however, affirmed that a 92 % efficiency was achievable at 25 °C, which was mitigated to 89 % at 55 °C. Eventually, the thermodynamic and adsorption isotherm records represented that Mint extract molecules mono-layer was constructed by utilizing the exothermic interactions. Via the MD and DFT simulations, the interfacial interactions and corrosion inhibitors' adsorption mechanism over the steel surface was exhibited. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, 4-amino-antipyrine (AAP) was grafted on graphene oxide (GO) via the hydrothermal strategy (GO@AAP) to improve the corrosion resistant property of epoxy coating. Transmission electron microscope (TEM), scanning probe microscope (SPM) and Raman techniques were employed to investigate the morphology and structure of GO@AAP nanohybrid, which also effectively confirmed the successful AAP grafted on GO surface. Electrochemical and salt spray results indicated that incorporating as-synthesized GO@AAP into epoxy coating powerfully enhanced the anti-corrosion property, which was greatly consistent with the mild steel morphology after corrosion experiment. Besides, after 60 days of immersion, the |Z| 0.01 Hz was 3.7 × 108 Ω·cm2, which was two order of magnitude higher than that of pure epoxy coating. Local electrochemical impedance spectroscopy (LEIS) was visually demonstrated the synergistic effect of physical shielding and corrosion inhibition of GO@AAP in 3.5 wt% NaCl solution. This work provides a new method to achieve the barrier and inhibition activities of epoxy coatings, which are suitable for heavy corrosion resistant application in harsh environment. [Display omitted] • A novel graphene oxide-4-amino-antipyrine (GO@AAP) nanohybrid was fabricated. • The prepared GO@AAP/EP presented superior anti-corrosion performance. • The impermeability-inhibition complementary corrosion protective mechanism was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • (E)-3- (5-bromo-2-hydroxystyryl) quinoxalin-2(1H)-one (FR178) and (E)-3-(5-fluoro- -hydroxystyryl) quinoxalin-2(1H)-one (FR179) are a new effective corrosion inhibitors for mild steel in 1.0 M HCl. • E)-3- (5-bromo-2-hydroxystyryl) quinoxalin-2(1H)-one (FR178) and (E)-3-(5-fluoro- -hydroxystyryl) quinoxalin-2(1H)-one (FR179) act as mixed-type inhibitors in 1.0 M HCl. • The adsorption of (E)-3-(5-bromo-2-hydroxystyryl) quinoxalin-2(1H)-one and (E)-3-(5-fluoro-2 hydroxystyryl) quinoxalin-2(1H)-one are well described by the Langmuir adsorption isotherm. • Surface characteristics analysis by MEB-EDS and DRX provided strong evidence for the existence of inhibition film on mild steel surface. • Quantum chemical parameters were correlated with experimental results. The evaluation of corrosion inhibition of mild steel (M−S) in 1.0 M HCl solution in the absence and the presence of different concentrations of (E)-3-(5-bromo-2-hydroxystyryl)quinoxalin-2(1H)-one (FR178) and (E)-3-(5-fluoro-2-hydroxystyryl)quinoxalin-2(1H)-one (FR179) was studied by electrochemical,and theoretical measurements. These organic inhibitors have proven to be effective corrosion inhibitors for the protection of mild steel.Increasing concentrations of inhibitors contributed to high inhibition efficiencies, which were attributed to the simple blocking action of the anodic and cathodic sites by adsorption of the inhibitors molecules onto the M−S surface. Their inhibition efficiencies can reach about 90.9 % and 91.5 % when the optimal concentration is 10-3M for the two inhibitors FR178 and FR179 respectively.On the other hand, as the temperature rises, the anti-corrosion capability of both FR178 and FR179 diminishes slightly and attains 82 % and 84 % respectively at the temperature of 328 K.Potentiodynamique polarization (PDP) and electrochemical impedance spectroscopy(EIS) demonstrated that both inhibitors examined act as mixed-type inhibitors.Furthermore, X-ray diffraction (XRD) and scanning electron microscopy coupled to energy dispersive spectroscopy (SEM/EDS) measurements indicated the formation of a protective layer adsorbed on the mild steel surface. The density functional theory (DFT) and molecular dynamics (MD) simulations were carried out to examine the correlation between molecular and chemical reactivity. The obtained results were found to be consistent with the experimental findings. [ABSTRACT FROM AUTHOR]

Recently, researchers have tried to find potential approaches for mitigating the metals' corrosion rate in aggressive environments. In the present study, the exploration of the Pepper extract's impact on the steel samples (SS) dissolution rate reduction in HCl media was done. The extract ingredients were detected by Raman, UV-Vis, and FT-IR approaches. The Pepper extract mechanism and effectiveness in corrosion mitigation were examined by polarization approach and EIS exam. Adsorption of the inhibitive components in the Pepper extract over a steel surface was theoretically studied by DFT calculation and MD simulation. Around 92% efficiency with mixed protection activity was recorded after 6 h of sample exposure to the 800 ppm Pepper extract-included solution at ambient temperature. The FE-SEM and AFM records confirmed the considerable surface degradation reduction on the Pepper extract-containing HCl solution-attacked samples. The weight loss test results have reflected 91% efficiency at 800 ppm and ambient temperature. However, by raising the harsh media temperature up to 55 ºC the anti-corrosion index was reduced 90%. The thermodynamic computation proved the exothermic adsorption of the molecules according to the Langmuir-type isotherm proving the monolayer Pepper extract molecules' interaction with the iron surface. [Display omitted] • The Pepper extract's impact on the steel dissolution rate reduction in HCl media was studied. • Adsorption of the inhibitive components in Pepper extract over steel surface was theoretically studied. • Around 92% efficiency with mixed protection activity was recorded after 6 h sample exposure to the 800 ppm Pepper extract. [ABSTRACT FROM AUTHOR]

• • BTTA exhibits more superior inhibition performance for steel corrosion than BTA due to S-linker. • • BTTA follows the characteristic of the mixed-type inhibitor. • • Theoretical modeling gives deep insights into adsorption and inhibition mechanism. Comparison of inhibition behavior of two tetrazole derivatives namely 5-(Benzylthio)-1H-tetrazole (BTTA) and 5-Benzyl-1H-Tetrazole (BTA) for Q235 steel in sulfuric acid has been investigated by electrochemical measurements, weight loss, FE-SEM, EDS, AFM, DFT, and molecular dynamics simulation. It is found that η values can reach 98.3% for 2 mM BTTA at 120 min, while BTA can only provide 21.6% in same condition. The significant promotion of inhibition performance corresponds to the existence of S-linker in the BTTA molecule, which induce the formation of stable multiple anchored BTTA layer on steel substrate. In other words, BTTA can exhibit more efficient chemical coordination ability with steel compared with BTA. The relevant action mechanism at molecular/atomic level was further analyzed based on Langmuir model and theoretical calculation. [ABSTRACT FROM AUTHOR]

• • Electrochemical test data indicate Pyracantha fortuneana alcohol extracts belong to mixed-type corrosion inhibitor. • • The Pyracantha fortuneana alcohol extracts adsorb on the Cu in accordance with the Langmuir model. • • Theoretical calculation provide in-depth understanding of the experimental results. Compared with traditional copper corrosion inhibitors, Pyracantha fortuneana alcohol extracts are derived from natural plants, will not cause environmental pollution after use, and are in line with the concepts of green chemistry and sustainable development. In this study, Pyracantha fortuneana alcohol extracts (PFAE) were obtained by ethanol soaking extraction method. PFAE, a novel degradable green corrosion inhibitor, has been investigated by experiments and theoretical calculations for its anti-corrosion performance of copper in H 2 SO 4 solution. Electrochemical experiments have demonstrated a pronounced increase in corrosion inhibition efficiency (η) as the concentration of PFAE rises. At a PFAE concentration of 600 mg/L, the inhibition efficiency can exceed 95 %. Additionally, the electrochemical method was used to investigate how the effect of soaked time on its anti-corrosion performance. After 4 h of immersion in a H 2 SO 4 solution containing PFAE, the copper could still maintain more than 80 % of the anti-corrosion performance. The results of surface morphology analysis demonstrate that after adding PFAE, the roughness of the copper sample is significantly reduced. This provides intuitively evidence that PFAE can indeed proficiently inhibit copper corrosion within a sulfuric acid solution. According to the study of the adsorption model, it was found that the adsorption behavior of PFAE onto the copper surface adheres to the Langmuir monolayer adsorption model. Moreover, the findings indicate the coexistence of both physical and chemical adsorption mechanisms. The findings of molecular dynamics simulations (MD) and quantum chemistry (QC) calculations indicate that the six active components of PFAE can display strong anti-corrosion capability. [ABSTRACT FROM AUTHOR]

The focus of recent research has been the development of organic films on the metal surface to achieve a desirable degree of metal protection. In this respect, more attention has been drawn to environmentally friendly compounds. Pigeon pea seed (PPS) extract is one of the natural and biodegradable compounds with a promising potency for corrosion inhibition. In this work, pigeon pea seed extract inhibited mild steel corrosion in strong acid electrolyte. To evaluate the efficiency and provide well-defined mass transfer operations, electro-kinetics, Tafel polarization, weight loss and molecular dynamics were applied. FTIR, SEM and AFM were employed to characterize the structure and nature of the organic film-based complexes formed on the steel plates. For the statistical analysis, particle swarm optimization (PSO) and response surface methodology (RSM) were used to evaluate the interactive effects between the independent variables and the expected responses. The result from electro-kinetics shows that pigeon pea seed extract is a practical protocol for the improvement of reliable steel corrosion resistance. Polarization measurement showed that due to the formation of the pigeon pea seed extract-based film on the mild steel, a successful corrosion inhibition of steel by a mixed-mode mechanism occurred. PPS exhibited good inhibition nature, and its inhibition efficiency can be as high as 94% when the concentration is 0.9 g/L−1 at temperature of 300 K. The adsorption kinetics adheres strictly to Langmuir model. The DFT studies complement with the experimental data. The MIMO model via RSM gave better prediction than PSO. Results from SEM/AFM photographs and FTIR confirmed that complexes based on the pigeon pea seed extract precipitated a protective film on the steel sample. [ABSTRACT FROM AUTHOR]

• Q and QN act as effective inhibitor for steel acidic corrosion. • Adsorption on the surface is analyzed by XPS, AFM, SEM/EDS and CA techniques. • Theoretical data provide in-depth understanding of the experimental results. Two quinoline derivatives such as 5-(ethoxymethyl)-2-methylquinoline-8-ol,and 5-((2-aminoethoxy)methyl)-2-methylquinoline-8-ol symbolized by (Q) and (QN), respectively were studied in HCl (1.0 M) by experimental, and computational approaches to inhibit the corroding of the mild steel (M-S). Q and QN were found to delay the corrosion of the mild steel in the research environment. Q and QN displayed mixed inhibiting properties, decreasing the rate of anodic and cathodic corrosion reactions. The Q and QN molecules developed a film on the surface of the material in HCl (1.0 M), which is consistent with the impedance measurements. Coverage data of the surface adsorption has fitted into the Langmuir adsorption isotherm. SEM/EDS, AFM, contact angle, and XPS analysis also indicated that the adsorbent film of Q and QN protects the steel from ions of acid. In addition, a molecular dynamics simulation was performed to optimize the inhibitor molecule equilibrium configurations at the Fe surface. From the experimental results, the sequence of the effectiveness of the studied inhibitors was validated through theoretical calculations. [ABSTRACT FROM AUTHOR]

• Toxicity results predicted that MF-PIT can be used with the concentration of 10−4 M without any problem. • DFT calculations predict high reactivity performance of MF-PIT. • MD simulation predict high interaction with Cu samples compared to MS and Al. • Electrochemical study was performed and confirmed the theoretically prediction results. • The surface characterization confirms the adsorption of MF-PIT. It is well known that the most practical approach to prevent metal from their degradation when it is in contact with aggressive solution is the application of inhibitors. The present work was designed to evaluate the inhibition behavior and the adsorption process of (E)‑1‑(5‑methylfuran‑2‑yl)‑3‑(6‑phenylimidazo[2,1‑b]thiazol‑5‑yl)prop‑2‑en‑1‑one (MF-PIT) for various metals (Copper (Cu), Mild steel (MS), and Aluminum (Al)) in 1 M HCl using electrochemical techniques, surface analysis characterization, and theoretical approaches. Firstly, DFT calculations and molecular dynamic simulation were executed to explore the reactivity of the studied inhibitor, and the adsorption configuration indicated in each metal. Before the experimental test, the environmental toxicity was evaluated and confirmed the safety of using the studied concentration. PDP results showed a good inhibition performance with inhibition efficiency of around 97.5% for copper, 95.9% for Mild steel, and 92.2% for Aluminum at the optimum concentration of 10−4 M. These results confirmed the EIS experiments and revealed that MF-PIT acted as a mixed-type inhibitor for the three metals. The adsorption of MFPIT obeyed the Langmuir isotherm model and form a strong bond with the studied metallic samples. The inhibition performance of MF-PIT showed a good correlation with the theoretical finding. [ABSTRACT FROM AUTHOR]

The two novel heterocyclic quinoline derivatives, 5-(methoxymethyl)-2-methylquinolin-8-ol (QO) and 5-((2-hydroxyethoxy)methyl)-2-methylquinolin-8-ol (QOOH) are examined in this work for their ability to adsorb against the corrosion of mild steel (MS) in a molar hydrochloric acid (HCl) media. After the synthesis of these two compounds, we proceeded some analytical methods such as the nuclear magnetic resonance of the proton and the carbon (1H NMR and 13C NMR). Potentiodynamic polarization (PDP), electrochemical frequency modification (EFM), and impedance spectroscopy (EIS) were the methods used in the experimental examination. The results indicated that the inhibitory efficacy of QO and QOOH increases with concentration. Both inhibitors exhibit mixed type behavior, according to the findings of polarization. Following that order was QO's and QOOH's inhibitory efficiencies 93.20% (QO) > 88.84% (QOOH). The Langmuir adsorption model is used in the adsorption process of these two chemicals. A barrier layer encasing the MS was shown to exist by Scanning electron microscope (SEM), energy dispersive X-ray analysis (EDS), atomic force microscopy (AFM), contact angle, and X-ray photoelectron spectroscopy (XPS) were all used in the examination of the surface characterization. The Density functional theory (DFT) findings suggest that inhibitors with electron-accepting capabilities exhibit the strongest interactions with the iron surface. • QO and QOOH act as effective inhibitor for copper acidic corrosion. • Adsorption on the surface is analyzed by XPS, AFM, SEM/EDS and contact angle techniques. • Theoretical data provide in-depth understanding of the experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • M2 and M3 act as effective inhibitors for steel acid corrosion. • The adsorption of M2 and M3 followed the Langmuir isotherm model. • adsorption on the surface is analyzed by AFM, SEM/EDS, XRD, and contact angle techniques. • Theoretical data provide in-depth understanding of the experimental results. In the current study, the adsorption of two new heterocyclic purine derivative compounds is investigated. namely, 7 H -purin-6-amine (Adenine) (M2) and 7 H -purin-6-amine (Adenine) (2R,3R,4S,5R) −2-(6-amino-9 H -purin-9-yl) −5-(hydroxymethyl) tetrahydrofuran-3,4-diol (M3) against the corrosion of mild steel in 1.0 M HCl medium. Weight Loss (WL), Electrochemical Impedance Spectroscopy (EIS), and Potentiodynamic Polarization (PDP) were among the techniques used in the experimental investigation. The respective inhibition efficiencies of M2 and M3 were found to be 89.0% and 96.5%.The Langmuir adsorption model was used to describe how M2 and M3 adsorb on the mild steel substrate. In addition, SEM/EDS, AFM, XRD, contact angle, and FT-IR techniques were employed to analyze the surfaces to support a protective film over the metal surface. Inductively coupled spectroscopy (ICP) was used to examine the WL observations as well. Furthermore, Molecular Dynamics (MD) simulations and DFT calculations were conducted to analyze the interaction of M2 and M3 with the mild steel substrate and their manner of adsorption. [ABSTRACT FROM AUTHOR]

In this paper, the corrosion inhibition performance of eco-friendly corrosion inhibitors 1-propyl-3-methylimidazolium bromide ([PrMIm]Br), 1-aminopropyl-3-methylimidazolium bromide ([APMIm]Br) and 1,4-bis(3-methylimidazolium-1-yl)butane dibromide ([BMImB]Br 2) was investigated for mild steel (MS) in H 2 SO 4 medium via experimental and theoretical methods. The results of electrochemical experiments show that the order of their corrosion inhibition is [BMImB]Br 2 > [APMIm]Br > [PrMIm]Br. The corrosion inhibition efficiency of [BMImB]Br 2 , [APMIm]Br and [PrMIm]Br are 92.9%, 88.0%, and 69.6% at the 303 K, respectively. The scanning electron microscope (SEM) morphology test results vividly prove that [BMImB]Br 2 has higher corrosion inhibition performance for [APMIm]Br and [PrMIm]Br. Weight loss experiments show that [BMImB]Br 2 and [APMIm]Br can still exhibit good corrosion inhibition nature with increasing temperature. Besides, the adsorption of three imidazole ionic liquids on the MS/solution interface is conform to Langmuir single-layer model, and they belong to the physical and chemical adsorption on the MS surface. Theoretical calculations explain their corrosion inhibition mechanism from an atomic or molecule perspective. • Electrochemical test data indicate [BMImB]Br 2 , [APMIm]Br and [PrMIm]Br belong to mixed-type corrosion inhibitor. • The corrosion inhibition performance is [BMImB]Br 2 > [APMIm]Br > [PrMIm]Br. • The corrosion inhibition mechanism was revealed by thermodynamic and kinetic analysis and theoretical calculation. [ABSTRACT FROM AUTHOR]

We report herein the synthesis of (E)-3-[2-(4-chlorophenyl)imidazo[1,2- a ]pyridin-3-yl]-1-mesitylprop-2-en-1-one (IMCH) as a new chlorophenyl-imidazole derivative that serves as an effective corrosion inhibitor for mild steel (MS) in 1 m HCl solution. IMCH bears additional electron donor groups and functional groups compared to previous inhibitors. Its chalcone structure has been confirmed by IR spectroscopy, 1H and 13C NMR spectrometry, and mass spectrometry. The corrosion inhibition efficiency of IMCH has been investigated by surface morphology (SEM and AFM) inspection, electrochemistry (EIS and PDP), and gravimetric, theoretical (DFT), and computational (Monte Carlo simulation) studies. It was found that the maximum protection of IMCH was 87.59% at a 1 m m loading. The adsorption of IMCH on a metal surface has been demonstrated using the Langmuir isotherm model, and its adsorption free energy has been evaluated as Δ G ads = −35.35 kJ/mol, indicating that the process is spontaneous and occurs through chemisorption and physisorption. The combination of a chlorine atom, an aromatic ring, and an imidazole moiety is mainly responsible for enhancing the corrosion inhibition of IMCH. DFT and MCS results have confirmed that the polarization, adsorption positions, π-system, and heteroatoms are key parameters in enhancing of corrosion efficiency of IMCH. [Display omitted] • A new IMCH ligand was synthesized and characterized. • Different techniques are applied to evaluate the inhibitive effect of IMCH. • IMCH exhibited a good protection affect against the corrosion of MS in HCl medium. • SEM and AFM surface analysis confirm the good protective effect of IMCH. • DFT and MCS outcomes support well the experimental findings. [ABSTRACT FROM AUTHOR]

[Display omitted] • ANN and QSAR-base predictive models are used for design of ionic liquids based corrosion inhibitors. • Quantum chemical descriptors and inhibitor's concentration are used for MLR and ANN. • The MLPNN model displayed better predictive performance than the MLR model. • Designed corrosion inhibitors show an inhibition efficiency higher than 80%. The present study reports the quantum chemical studies and quantitative structure activity relationship (QSAR) modeling of thirty ionic liquids utilized as chemical additives to repress mild steel degradation in 1.0 M HCl. Five molecular descriptors obtained from standardization of calculated descriptors together with the inhibitor concentration were employed in model building. Multiple linear regression (MLR) and multilayer perceptron neural network (MLPNN) modeling were utilized in model construction. The optimal MLPNN model was developed using a network architecture of 6-3-5-1 with Levenberg-Marquardt as the learning algorithm. The model yielded an MSE of 29.9242, RMSE of 5.4703, MAD of 4.9628, MAPE of 5.7809, rMBE of 0.1202 and CoV of 0.0052. The MLPNN model displayed better predictive performance than the MLR model. Furthermore, developed models were applied to forecast the inhibition efficiencies of five novel ionic liquids. The theoretical inhibitors were found to be effective inhibitors of steel corrosion, showing over 80% inhibition efficiency. [ABSTRACT FROM AUTHOR]

• Ranunculus bulbosus extract was used as a new environmentally-friendly corrosion inhibitor of MS exposed to 1 M HCl solution. • Using 2000 ppm Ranunculus bulbosus extract resulted in 94% corrosion inhibition efficiency according to EIS test results. • The inhibitor showed mixed inhibition and its adsorption obeyed a Langmuir isotherm. • Molecular simulations associated with DFT modeling highlighted the green ingredients adsorption on the steel. Owing to the movement toward greener earth, this study is a small contribution to this global process. The current research selected the Ranunculus bulbosus (RB) molecules in order to evaluate whether its extract could impart a corrosion-preventive quality to the MS attribute in the HCl condition. To reach this point, some distinct, as well as related tests, were performed. FESEM and AFM confirmed the positive impact of RB extract (RBE) upon the microstructure; the RBE addition considerably smoothened the surface in contrast with the sample doped with no RBE. UV–Vis showed the presence of several functional groups on the surface; while GIXRD provided the reason for the possible complexation of RBE molecules with Fe. Raman test confirmed the presence of inhibitor molecules on the surface via analyzing the carbon-based structures' existence. EIS was used for the corrosion-related analysis, and the increment of inhibitor concentration to 2000 ppm in company with 5 h of drowning time maximized the potency of corrosion resistance to 94%. Also, the corrosion-preventive performance of the RBE was supported by potentiodynamic polarization tests. RBE adsorbed over the surface via Langmuir regulation. Quantum chemical calculations based on the density functional theory (DFT) and molecular dynamics (MD) simulation have delivered helpful information regarding electron transfer and mechanism during adsorption of inhibitor ingredients on the mild steel surface. MD simulation revealed the interaction of inhibitors molecules and surface in addition to their high coverability. Also, DFT results suggested that electron sharing could occur between inhibitors molecules as metallic surfaces. In the end, the comparison of other studies with the current one was provided, and the mechanism was discussed. [ABSTRACT FROM AUTHOR]

The corrosion of low–carbon steel in aggressive alkaline–saline environments is a very large problem. Protecting low–carbon steel from corrosion in aggressive alkaline–saline solutions using green inhibitors is a very important task in industry. However, there are no studies related to low–carbon steel corrosion in aggressive alkaline–saline environments. Green type corrosion inhibitors are an interesting topic of research. However, currently, the studied type inhibitors are not efficient at low concentrations, and there are no studies on them in aggressive alkaline–saline environments in regard to steel corrosion. In this research work, a novel gossypol–indole modification (GIM) is introduced as a green corrosion inhibitor for low–carbon steel in an aggressive alkaline–saline environment. This inhibitor is a large, highly planar structural molecule that is more water soluble than other inhibitors. Its inhibition behavior is stable at high temperatures, and it contains a large number of electron–rich heteroatoms. All of these properties make it an excellent corrosion inhibitor. The inhibition performance of the novel gossypol–indole modification for low–carbon steel in 1 M NaOH + 1 M NaCl is fully characterized by thermodynamic, gravimetric, electrochemical frequency modulation (EFM), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), density functional theory (DFT), molecular dynamics (MD) simulations, scanning electron microscopy (SEM) and energy dispersive X–ray spectrometry (EDX) methods. The results confirm that the novel gossypol–indole modification is an excellent inhibitor, with a maximum inhibition efficiency of 96.01% at 100 mg/L and 0.112 mM. The adsorption behavior follows the Langmuir isotherm. Electrochemical studies have indicated that this modified is a mixed–type corrosion inhibitor, and the theoretical investigations correlate well with the experimental results. [Display omitted] • Gossypol–indole modification is green and powerful corrosion inhibitor. • The maximum inhibition efficiency of GIM was 96.01% at 100 mg/L/0.112 mM. • GIM is mixed–type corrosion inhibitor. • Corrosion–cathodic and –anodic activities of low–carbon steel in aggressive alkaline–saline environment are significantly blocked with GIM. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of new Schiff bases based on imidazo[1, 2-a]pyridine. • Characterization of the synthesized ligands by different spectroscopic methods such as: NMR, MS, IR and melting point. • Valorization of these products as corrosion inhibitors. • Combination of AFM and SEM observations of the steel surface. • DFT and Molecular dynamics simulation studies to validate the experimental results. In the present work, the synthesis of two new imidazo[1, 2-a]pyridine derivatives belonging to the schiff base family was performed. They are named respectively : (E)-N-(7-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1-(thiophen-2-yl)methanimine ( IP 1) and (E)-N-(7-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1-(5-nitrothiophen-2-yl)methanimine ( IP 2). The ligands were synthesized from a condensation reaction between 2-phenylimidazo[1,2-a]pyridin-3-amine and a commercial aldehyde (2-thiphencarbaldehyde for IP 1 and 5-Nitro-2-thiophencarbaldehyde for IP 2 in the presence of a catalytic amount of acetic acid in diethyl ether). The structures of the titrated compounds were determined using various spectroscopic techniques such as 1H NMR, 13C NMR, FT-IR and MS. However, the synthetic ligands showed very good inhibitory efficacy against corrosion of mild steel in 1 M HCl medium. This was evaluated by various electrochemical techniques such as mass loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The experimental results showed that the inhibitory efficiency of the synthesized ligands improves with the increase of concentration to reach the maximum value of 91% for IP 1 and 96% for IP 2 for a concentration of 10−3M, which translates that the surface covered by the inhibitor increases with the concentration. In addition, quantum chemical calculation based on density functional theory (DFT) confirmed the existence of good correlations between experimental and predicted spectroscopic data. Surface analysis carried out by SEM and AFM showed a smooth surface in the presence of the ligands IP 1 and IP 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Expired salbutamol (SB) drug chemically adsorbed on a mild steel surface. • Theinteraction of Fe and SB (Fe-O) bonded and functionalized the metal surface. • Polymerization of SB resulted in the inhibitor's film coverage as a protective layer. • Polarization test confirmed SB as a mixed-type inhibitor. • Artificial intelligence gave optimum system prediction. The study aims to establish detailed surface adsorption of expired salbutamol drug molecule as an emerging anticorrosion additive for mild steel corrosion in oilfield acidizing fluid. To achieve this, wide experimental data from weight loss, potentiodynamic polarization, and DFT studies were considered, statistically analyzed, and modeled. Artificial neural network-genetic algorithm (ANN-GA) and adaptive neural fuzzy inference system-genetic algorithm (ANFIS-GA) were utilized as optimization tools considering multiple inputs and a single output variable (MISO). Maximum inhibition efficiencies of 80 %, 89 % and 84 % were obtained from weight loss, potentiodynamics study and elcectrochemical impedance spectroscopy at concentration of 0.4 g/L-1SB and temperature of 323 K respectively. The results obtained from the polarization test confirmed SB as a mixed-type inhibitor and the kinetic studies fit well in the Langmuir isotherm for surface adsorption. The surface analysis via FTIR, SEM/EDAX, and AFM strongly complements the DFT results. In the soft computing method without (GA) via artificial neural network (ANN) and adaptive neural fuzzy inference system (ANFIS), optimal prediction of 79.74 and 81.24 % was attained at varying operating conditions. The predictive capabilities of the two methodologies were compared in terms of coefficient of determination (R2), chi square (χ2), root mean square error (RMSE) and model predictive error (MPE). Based on the statistical indices obtained, much credence was giving to ANFIS as the best predictive model over ANN. Effect of time and inhibitor concentration are the most significant parameters for the prediction of salbutamol drug as a potential anticorrosion additive for mild steel in oilfield acidizing conditions. [ABSTRACT FROM AUTHOR]

• The EIS has confirmed, that at 100 mg/L extract shows inhibition efficiency > 95%. • At LCS surface adsorption of extract has been confirmed by SEM and AFM techniques. • The adsorption behavior of main phytochemicals has been explained by DFT and MD. The soxhlet extraction method was used to prepare the extract of Cinnamoum tamala (C. tamala). Corrosion resistance performance of C. tamala leaves extract for low carbon steel (LCS) in the solution of 0.5 M H 2 SO4 was examined by Eletrochemical impedance spectroscopy (EIS), Tafel and gravimetric loss studies. Notably, C. tamala showed much high 96.76% industrial required efficiency at very low 100 mg/L critical concentration. Theoretical studies, using UV–vis, Density functional theory (DFT) and molecular dynamics (MD) simulation, were led as a valuable report for understanding the electronic adsorption, comparative inhibitory activities of phytochemicals. The results obtained revealed that C. tamala extract might be used as a highly efficient industrial required corrosion inhibitor. [ABSTRACT FROM AUTHOR]

• PY-2Cl and PY-2Cl act as effective inhibitors for MS acidic corrosion. • The adsorption of PY-2Cl and PY-2Cl followed the Langmuir isotherm model. • Adsorption on the surface is analyzed by AFM, SEM/EDS, XRD, and FTIR techniques. • Theoretical data provide in-depth understanding of the experimental results. The present paper examines the adsorption of two novel heterocyclic compounds of the pyran derivatives, namely, 2-amino-4-(2-chlorophenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (PY-2Cl) and 2-amino-4-(4-chlorophenyl)-5-oxo-4,5-dihydropyrano[3,2c]chromene-3-carbonitrile (PY-4Cl) against the corrosion of mild steel (MS) in molar hydrochloric acid (HCl) medium. The experimental investigation was carried out utilizing a series of techniques including Weight Loss (WL), Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP). Results showed that inhibition effectiveness of PY-2Cl and PY-4Cl increases with their concentration. Polarization results showed that PY-2Cl and PY-4Cl displayed mixed type behaviour. Inhibition efficiencies of PY-2Cl and PY-4Cl followed the order: 85.8% (PY-4Cl) < 91.2% (PY-2Cl).The adsorption process of PY-2Cl and PY-4Clonto MS surface follows Langmuir adsorption model. Surface characterization analysis utilizing Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDS), Atomic Force Microscopy (AFM)and Infrared Spectroscopy (FT-IR) supported the existence of a barrier layer covering the MS. WL measurements were also tested utilizing inductively coupled spectroscopy (ICP) and UV–vis spectrometry (UV–vis). [ABSTRACT FROM AUTHOR]

• Quantum chemical parameters of BTA and M-BTA were evaluated by DFT theory. • N7 and N8 atoms of BTA and M-BTA are the coordination sites of the inhibitors. • Adsorption energy of BTA and M-BTA in gaseous and aqueous phases on Cu(111) surface was calculated by Mont Carlo simulation. • Inhibition efficiency of BTA and M-BTA was calculated by electrochemical experiments. The corrosion inhibition effects of benzotriazole (BTA) and its derivative-methylbenzotriazole (M-BTA) at molecular level were studied using quantum chemical method. The adsorption mechanism of inhibitors on copper surface was evaluated by Density Functional Theory (DFT) at BLYP/3.5DNP level and Monte Carlo simulation. The inhibition effects of BTA and M-BTA were investigated by chemical reactivity parameters. Both inhibitors have a considerable excess of negative charges around the nitrogen atoms N7 and N8, indicating that they are the coordination sites of the inhibitors. Under the circumstance of gaseous and aqueous phases molecules, the BTA adsorption and M-BTA adsorption on Cu (111) surface was further simulated by Monte Carlo simulations. In addition, the interaction energy between inhibitors and copper was calculated. The electrochemical measurement results confirm that the inhibition effect of 15mM M-BTA is greater than that of BTA, and the inhibition efficiency is up to 96.05%, which is helpful for further study of corrosion system. [ABSTRACT FROM AUTHOR]

• Corrosion inhibition of mild steel in 0.5 mol/L H 2 SO 4 by different solvent fractions of bamboo shoots extract were investigated. • Inhibition efficiencies were experimentally achieved by electrochemical and weight loss techniques. • Surface characterizations have been performed by SEM and XPS tests. • Experimental results have been combined by theoretical studies (DFT and MD). The ethanol extract of bamboo shoots was obtained by refluxing bamboo shoots in 95 % ethanol, and then the ethanol extract from bamboo shoots were separated by organic solvents with different polarity, including petroleum ether, dichloromethane, ethyl acetate and n-butanol. The inhibitive effect of different solvent extraction fractions of bamboo shoot extract on the corrosion of mild steel in 0.5 mol/L H 2 SO 4 solution was investigated through electrochemical technique, weight loss test, scanning electron microscope and X-ray photoelectron spectroscopy. Electrochemical results showed that all extraction fractions of bamboo shoots extract, as modest cathodic inhibitors, mainly inhibited the cathodic reaction of mild steel in 0.5 mol/L H 2 SO 4 solution, and the inhibition efficiency of extraction fraction increased with the increase in its concentration. When the concentration was 0.4 g/L, the corrosion inhibition efficiency of dichloromethane fraction (DCMF), n-butanol fraction (nBF), ethyl acetate fraction (EAF) and the residual fraction (RF) are 93.03%, 89.62%, 85.33% and 64.84%, respectively. However, the results of weight loss experiment showed that when the experimental time increased from 4 h to 24 h, the inhibition efficiency of DCMF and EAF decreased significantly, but that of nBF remained at about 86%, showing a better long-term effect. Surface analysis technology was used to investigate the corrosion inhibition and adsorption behavior of the extraction extraction fractions, and the adsorption of different solvent extraction fractions of bamboo shoot ethanol extract on mild steel surface was in accordance with the equation of Langmuir isotherm. [ABSTRACT FROM AUTHOR]

• Electrochemical tests were done on mild steel samples in 0.5 M sulfuric acid solution. • Maximum corrosion inhibition efficiency (>95%) was obtained with 500 mg/L. • Adsorption of phytochemicals was studied by DFT and MC simulations. • SEM and AFM verified the surface adsorption of P. somniferum. The corrosion resistance of iron alloy in 0.5 M sulphuric acid was checked in the presence and absence of Papaver somniferum (P. somniferum) seed extract. Notably, P. somniferum showed 95% corrosion resistance efficiency at 500 mg/L concentration. The adsorption of this inhibitor follows the Langmuir isotherm indicating its monolayer formation on the surface of iron alloy. The potentiodynamic experiments indicated its nature as mixed type of inhibition behaviour. The SEM and AFM techniques were used to study the protective layer on iron alloy. FT-IR with ATR confirmed various functional groups containing heteroatoms present in phytochemicals and formed complex with iron respectively. Theoretical studies were given as a valuable report to understand the comparative adsorption of phytochemical. All acquired outcomes confirmed that P. somniferum seed extract act as an efficient corrosion inhibitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesized N,S-CDs contains N and S as high as 17% and 19%, respectively. • N,S-CDs was firstly as corrosion inhibitor for copper with excellent anti-corrosion performance. • The interaction bewteen N,S-CDs and copper mainly belong to the chemisorption. In this study, a novel N and S co-doped carbon dots (N,S-CDs) had been prepared with content of N and S as high as 17% and 19%, respectively. Combining electrochemical, Fourier transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS) and micromorphology techniques to assess the inhibition performance of the N,S-CDs for copper in sulfuric acid solution. The new nanomaterials dispaly excellent effectiveness for copper (99.88%) at the concentration of 50 mg/L in 0.5 M H 2 SO 4 solution, this work could provide a new idea for exploring environment-friendly and high efficient corrosion inhitiors for metal protection. [ABSTRACT FROM AUTHOR]

[Display omitted] • A long-chain alkyl-substituted decyltriphenylphosphoniumbromide (DTPPB) was tested as corrosion inhibitor. • DTPPB showed highest inhibition efficiency of 99.5% at 10-4 M concentration. • SEM, EDX, and AFM analyses showed that DTPPB becomes effective by adsorbing on the metal surface. • DTPPB acted as mixed-type corrosion inhibitor. • DFT and MDS based theoretical studies were conducted to corroborate the experimental results. A triphenylphosphonium based ionic liquid containing a long hydrophobic alkyl-chain (designated as DTPPB) was evaluated as a potential corrosion inhibitor for mild steel (MS) in 0.5 M H 2 SO 4 solution. Inhibition efficiency and adsorption behavior of DTPPB was determined by performing the experimental analyses were carried out at the different concentration and temperature. Corrosion inhibition effectiveness of DTPPB was determined experimentally using electrochemical and surface analyses (SEM-EDX and AFM). Polarization studies showed that DTPPB acted as a mixed-type inhibitor. Inhibition effectiveness of DTPPB increases with increasing its concentration. The potentiostatic polarization study revealed that passivation was perceived at lower DTPPB concentrations. The Nyquist plot of impedance is expressed mainly as a depressed capacitive loop with different concentrations. Self-organization of the chains and tail groups to form a coherent hydrophobic film that serves as a barrier for the transport of water, oxygen, and corrosive ions to the metal surface. In addition to the electrochemical studies, surface morphology analyses provided strong evidence for the existence of inhibitor film over the MS surface and their results were supported by the computational data. [ABSTRACT FROM AUTHOR]

• Q-1 and Q-2 act as effective inhibitors for MS acidic corrosion. • The adsorption of Q-1 and Q-2 followed the Langmuir isotherm model. • Adsorption on the surface is analyzed by AFM, SEM/EDAX and XRD techniques. • Theoretical data provide in-depth understanding of the experimental results. The present investigation focused on the corrosion inhibition of mild steel in 1.0 M HCl medium by new naphthol based on 8-hydroxyquinoline. These products were characterized by 1H-NMRand 13C NMR spectroscopy. The influence of concentration (C) and temperature (T) on the corrosion process of mild steel before and after addition of naphthol derivatives in corrosive solutions has been investigated through weight loss (WL), electrochemical measurements :electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). PDP findings revealed that the used naphthol derivatives exhibit a mixed character. Inhibition efficiencies of Q-1 and Q-2 followed the order: 87.6% (Q-1) < 90.9% (Q-2). The study has shown that these inhibitors act through adsorption mechanism onto steel surface following Langmuir isotherm. The surface analyzes were carried out by SEM, EDS, AFM, and XRD. The corrosive solutions were analyzed by UV–visible and ICP-OES. Experimental and spectroscopic studies were confirmed using DFT calculations and MD simulations. [ABSTRACT FROM AUTHOR]

• Thioglycoluril was introduced as a new and green corrosion inhibitor for low carbon steel in aggressive acidic media. • The inhibition efficiency of BSTGCU was over 96% at 100 mg/L. • Electrochemical measurements suggested that BSTGCU is a mixed-type inhibitor. • Theoretical results confirmed that the inhibition performance of BSTGCU was better in its protonated form than in its neutral form in the aqueous phase. Thioglycoluril (3a,6a−bistolylthioglycoluril (BSTGCU)) was first introduced as a new and green corrosion inhibitor for low carbon steel in a 1 M HCl medium. The inhibition properties of BSTGCU in a 1 M HCl were fully characterised by the gravimetric, thermodynamic, potentiodynamic polarisation (PDP), electrochemical impedance spectroscopy (EIS), electrochemical noise (EN), electrochemical frequency modulation (EFM), density functional theory (DFT), molecular dynamics (MD) simulations, scanning electron microscopy (SEM) and energy dispersive X −ray spectrometry (EDX) methods. The experimental results confirmed that the maximum inhibition efficiency of BSTGCU was over 96% at 100 mg/L in a 1 M HCl medium. The electrochemical results indicated that BSTGCU acted as a mixed−type inhibitor and spontaneously adsorbed on the metal surface by physical and chemical adsorption mechanisms according to its Langmuir adsorption isotherms. The SEM−EDX results of the inhibited steel sample revealed that the surface morphology was significantly improved with the presence of inhibitor. Theoretical calculations confirmed that the inhibition properties depended on the molecular structure of BSTGCU, and its inhibition performance was better in its protonated form than in its neutral form in the aqueous phase. [ABSTRACT FROM AUTHOR]

The corrosion inhibition of aluminum alloy 2024-T3 by two organic compounds, 5,5′-dithiobis-(2-nitrobenzoic acid) (ER) and sodium sulfite (SUL), in 3.5% NaCl is investigated at various temperatures using electrochemical techniques, such as impedance spectroscopy (EIS) and potentiodynamic polarization. The polarization curves indicate that the inhibitors tested acted as cathodic inhibitors. The inhibition efficiency (IE %) increased with increasing inhibitor concentration to 93% at 10−2 M ER and 98% at 5.10−3 M of SUL. Moreover, adsorption of the compound on the surface of aluminum in 3.5% NaCl follows the Langmuir isotherm model. Data obtained from EIS studies are analyzed to model the interface of the metal/solution through appropriate equivalent circuit models. We study the temperature effect on the corrosion behavior of the aluminum alloy in 3.5% NaCl with and without the inhibitors. The adsorption free energy and activation parameters of the aluminum dissolution reaction in the presence of ER and SUL are determined. The results of SEM-EDS analyses support the adsorption inhibition mechanism. DFT using B3LYP/6-311G (d,p) is also performed in order to determine the correlation between the corrosion inhibition properties of the examined derivatives and their molecular structures. The adsorption of the compounds is confirmed by MD simulations. The experimental results support the theoretical outcomes. • ER and SUL act as effective inhibitors for AA2024-T3 alloy in Saline Solution. • The adsorption of ER and SUL followed the Langmuir isotherm model. • SEM/EDS show the existence of a stable and insoluble adherent deposit. • Theoretical data provide in-depth understanding of the experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] A great deal of consideration has been given to the development of new compounds having diverse functionality. In this report, a new indazole derivative bearing a nitro group, namely 2-(3-chloro-5-nitro-1 H -indazol-1-yl) acetic acid (CNIA) was synthesized, characterized, and used as corrosion inhibitor for mild steel (MS) in 1.0 M HCl. A full characterization of the prepared compound was performed using single‐crystal XRD, FT-IR, and UV–vis measurements; its corrosion inhibition properties were experimentally evaluated by potentiodynamic polarization (PDP) curves as well as electrochemical impedance spectroscopy (EIS) measurements, and theoretically by Density Functional Theory (DFT) and molecular dynamics (MD) simulations. Scanning electron microscope (SEM) was used to examine the morphology of the corroded metal surface before and after the inhibition. The findings demonstrated that the application of CNIA significantly reduced the corrosion rates of MS. The corrosion inhibition ability of the synthesized compound was also identified at a lower concentration in all experiments, reaching a maximum of 89 % at 10−3 mol/L. The results of potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) confirmed that CNIA could be categorized as a mixed type inhibitor with an increased polarization resistance at higher concentrations. Langmuir's adsorption isotherm was found to fit the adsorption of CNIA molecules on the MS surface. SEM photographs showed obvious less-corroded morphologies in the presence of the CNIA as compared to untreated MS surface. Theoretical calculations were proposed to explain the mechanism of the inhibition effect and found that it is due to the donor/acceptor properties of the inhibitor and its parallel disposition over the steel surface. The present compound could be a promising corrosion inhibitor for mild steel in HCl solutions, and showed a corrosion inhibition property that is superior to similar compounds. [ABSTRACT FROM AUTHOR]

Currently, there are several types of corrosion inhibitors were studied. The new type of corrosion inhibitor based on a gossypol derivative was first introduced. The anti-corrosion performance of 6-aminopenicillanic acid sodium gossypol (APASG) for St2 steel in a 1 M HCl + 1 M KCl solution was reported for the first time, and the inhibition properties of this material were fully characterized by gravimetric analysis, thermodynamic analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), electrochemical noise (EN) analysis, electrochemical frequency modulation (EFM), density functional theory (DFT), molecular dynamics (MD) simulations, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX). The obtained results show that APASG is an excellent anti-corrosion inhibitor (97% at 100 mg/L/0.104 mM) at intermediate temperatures (303−333 K). APASG adsorbed onto a metal surface by a physical and chemical adsorption mechanism, as shown by the Langmuir adsorption isotherms. Electrochemical analyses show that APASG acts as a mixed-type inhibitor. The thermodynamic adsorption data were measured and discussed. SEM-EDX tests of the inhibited steel sample show that the inhibitor significantly improved the surface morphology. DFT calculations indicated that the broadly stretched linked functional groups (hydroxyl and carboxyl) and heteroatoms (nitrogen, oxygen and sulfur) in the inhibitor structure are responsible for the inhibition efficiency of APASG. The obtained DFT and MD simulation data supported the experimental results. Unlabelled Image • APASG was excellent corrosion inhibitor for St2 steel in 1 M HCl + 1 M KCl medium. • Maximum inhibition efficiency of APASG was 97% at 100 mg/L. • APASG is a mixed type corrosion inhibitor. • A variety of thermodynamic, kinetic and electrochemical parameters were measured and discussed. • APASG adsorb on the Fe/solution surface in accordance with the Langmuir model. [ABSTRACT FROM AUTHOR]

The anti-corrosion potency of three synthesized 8-hydroxyquinoline derivatives, namely 5-(azidomethyl)-7-(morpholinomethyl)quinolin-8-ol (HM1), 2-(8-hydroxy-7-(morpholinomethyl)quinolin-5-yl)acetonitrile (HM2), 5-(azidomethyl)-7-(piperidin-1-ylmethyl)quinolin-8-ol (HM3) in hydrochloric acid for mild steel was investigated using weight loss and electrochemical techniques. Potentiodynamic polarization (PDP) data reveal that all three compounds were cathodic inhibitors, with HM3 presentation significant mixed-type effect at high inhibitor concentrations (10−3 M). Electrochemical impedance spectroscopy (EIS) data reveal better adsorption of compounds species on MS surface at increased inhibitor concentrations with HM1 , HM2 and HM3 reaching a maximum efficiency of 90, 89 and 88%. The three compounds HM1 , HM2 and HM3 were inclined towards the Langmuir adsorption-isotherm by spontaneous chemical-physical adsorptions of inhibitors on the mild steel surface. The correlation between the electronic properties and inhibition efficacies of the tilted inhibitors was determined by using simple linear regression technique. Electronic properties were calculated for neutral and protonated forms in a polarizable continuum model using the DFT method at the B3LYP/6–311 + G (d, p) level of theory. The active adsorbed sites of HM1 - HM3 on the metal surface were determined by analyzing their corresponding electrostatic surface potentials (ESP). Furthermore, molecular dynamics simulations have been performed to illustrate the most conceivable adsorption configuration between the inhibitors and metal surface. Unlabelled Image • Synthesis and investigation of the corrosion inhibition of three 8-hydroxyquinoleine derivatives. • The adsorption of inhibitors obeys Langmuir adsorption isotherm. • DFT modelling and Molecular dynamics simulations provided molecular level insights. • Correlation between the corrosion inhibition and quantum chemical and molecular dynamic stimulation results. [ABSTRACT FROM AUTHOR]