Adsorption Of Inhibitor Research Articles

Exploring the potent corrosion inhibition properties of phenolic Schiff bases on mild steel in acidic environments, part A: coupling experimental and theoretical investigations.

In this study, we conduct a comparative investigation into the corrosion inhibition properties of two Schiff base compounds, namely 4,4'-((1E,1'E)-(ethane-1,2 diylbis(azaneylylidene))bis(methaneylylidene))diphenol (PSB5) and (1E,1'E)-N,N'-(ethane-1,2 diyl)bis(1-(4-nitrophenyl)methanimine) (PSB6), on mild steel in an acidic environment. The inhibitory efficiency and adsorption behavior of the inhibitors were assessed through electrochemical and gravimetric analyses. The inhibitors' deposition was further verified by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The findings of electrochemical tests demonstrate that these chemical compounds are potent inhibitors, with 96.5% inhibition provided by PSB5 at 10-3M. Therefore, PSB5 and PSB6 inhibitors are likely of mixed-form, as evidenced by changes in their Ecorr values of 59.8 mV and 33.0 mV, respectively when compared to the blank solution. Furthermore, the adsorption of these inhibitors onto the MS surface, as determined by the Langmuir adsorption isotherm, yielded free energy values of - 38.40 kJ mol-1 for PSB5 and - 35.20 kJ mol-1 for PSB6. These findings highlight a robust and spontaneous adsorption process for both inhibitors. Surface analysis using SEM-EDS revealed the preservation of the mild steel surface morphology and the adsorption of inhibitors. Theoretical investigations utilizing density functional theory (DFT) and molecular dynamics (MD) simulations supported and complemented the experimental findings. This research enhances the understanding of the corrosion protection potential of Schiff base compounds and their potential applications in various industries.

Impact of N-Decyl-Nicotineamide Bromide on Copper Corrosion Inhibition in Acidic Sulphate containing Environment: electrochemical and Piezoelectrochemical Insights

This work investigates the inhibition effect and adsorption properties of a new tailor-made synthesized model molecule of ionic liquids, namely N-decyl nicotinamide bromide [C10Nic]Br in an acidic 0.1 M Na2SO4 solution (pH = 2.7) against the corrosion of copper. Electrochemical methods (ac electrochemical impedance spectroscopy and dc potentiodynamic polarization), and piezoelectric method (quartz crystal microbalance with impedance analysis (EQCM-I) were applied to study the corrosion protection performance of the inhibitor. Electrochemical measurements have indicated favorable corrosion inhibition performance of [C10Nic]Br. The corrosion inhibition efficiency increases with the increase of inhibitor concentration, at a [C10Nic]Br concentration of 10-3 M the efficiency reaches 93%. The inhibitor adsorption slightly differed from the ideal Langmuir adsorption isotherm. [C10Nic]Br can be considered to be a mixed-type inhibitor. The inhibition efficiency was found to be time-dependent. In the presence of the highest 10-3 M inhibitor concentration the formation of the maximum protective effect of the inhibitor layer takes several hours, the maximum value of polarization resistance was 8.5 kΩ.cm2 after 5 hours. The copper dissolution and the inhibitor adsorption were also monitored by real-time changes in mass and viscoelasticity determined by QCM-I. It was obtained that the inhibitor adsorption on the copper surface leads to a decrease in copper dissolution and an increase in viscoelasticity. The layer on the copper surface becomes softer due to the complex between the inhibitor and the corrosion products on the surface.

Aromaticity of Heterocyclic Compounds and Their Corrosion Inhibition Property: Experimental and Theoretical Analysis.

Heterocycle derived moieties, namely, N-(4-methoxyphenyl)-1-(1H-pyrrol-2-yl)methanimine (MPM), 1-(furan-2-yl)-N-(4-methoxyphenyl)methanimine (FMM), and N-(4-methoxyphenyl)-1-(thiophen-2-yl)methanimine (MTM), were synthesized followed by analysis of their structural aspects using FTIR and 1H NMR spectroscopic techniques. The corrosion retarding abilities of the same were distinguished by gravimetric and certain electrochemical measures for mild steel in 0.5 M H2SO4, and MTM was obtained with maximum inhibition efficiency of 97.93% at 250 mg L-1 concentration; the thermodynamic and activation parameters were recorded in this regard. The results were further seen to be supported by various surface studies: SEM-EDS, XPS, AFM, contact angle, and UV-visible spectroscopy. Potentiodynamic polarization studies unveiled the mixed nature of heterocyclic inhibitors with overriding anodic effect. Furthermore, the adsorption of inhibitors over mild steel coupons demarcates the prevalence of physical and chemical interactions in the environment. In addition, the computational studies, global and local reactivity, molecular dynamics, and density functional theory, were employed and the experimental results obtained were found in correlation with the theoretical results.

Synthesis, characterization and corrosion inhibition evaluation of a new chalcone derivative 2-3-(3-hydroxyphenyl)-1-[4-(1H-imidazol-1-yl) phenyl] prop-2-en-1-one for mild steel corrosion in 1M HCl assessment with DFT and MD studies

The prime objective of the work focuses on the synthesis of novel chalcone derivative, the 2-3-(3-hydroxyphenyl)-1-[4-(1H-imidazol-1-yl) phenyl] prop-2-en-1-one (HIPP) and study its corrosion inhibition for mild steel in 1M HCl. Various spectroscopic techniques such as IR, 1H-NMR, 13C-NMR, and mass spectroscopy were used to confirm the formation of the synthesized chalcone. Distinct electrochemical techniques like potentiodynamic Tafel polarization and impedance spectroscopy were employed to investigate HIPP in 1M HCl as a mild steel corrosion inhibitor. The synthesized chalcone was checked in a temperature range varying from 30o C to 60o C. With increasing quantities of HIPP, it is noticed that there is an enhancement in calculated corrosion inhibition efficiency. The maximum inhibition efficiency obtained was found to be 94.3 % in the presence of 100 ppm at room temperature. Surface morphology of unhindered and inhibited HIPP was analysed using scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle (WCA) measurements. SEM investigation revealed that the inhibitor effectively protects the metal surface from aggressive corrosion. Atomic force microscopic images show the corroded MS surface roughness in the presence of HIPP reduced from 342.1 nm to 174.3 nm. Furthermore, the inhibitor's adsorption through electron-donor acceptor interactions was revealed by DFT calculations and MD studies.

Synthesis of a new quaternary ammonium salt for efficient inhibition of mild steel corrosion in 15 % HCl: Experimental and theoretical studies

The corrosion phenomenon and its economic impacts can hardly be ignored in any application. This study synthesized a quaternary ammonium salt (3) containing hydrophobic dodecyl and electron-rich diallylbenzyl amine moieties to be used in 15 % HCl as a corrosion inhibitor of mild steel. Several techniques, such as 1H and 13C NMR, IR, TGA, and elemental analysis, have been used to characterize inhibitor 3. Popular corrosion measurement techniques, namely weight loss, potentiodynamic polarization techniques, and electrochemical impedance spectroscopy, have been used to determine the efficiency of inhibitor 3. At 303 K and a moderately low concentration of 50 ppm, the quaternary ammonium salt-based inhibitor demonstrated a maximum efficiency of ≈95.0 %. At elevated temperatures of 313, 323, and 333 K, the inhibition efficacy values were recorded as 91.3, 82.8, and 75.0 %, respectively. Adsorption isotherm study revealed that the adsorption of inhibitor 3 followed Langmuir adsorption isotherm. The value of ΔGads° was found to be – 40.19 kJ mol−1, indicating that inhibitor 3 became adsorbed via a mixed physi-chemisorption mechanism. A very high adsorption constant (Kads) of 1.53 × 105 L mol−1 suggested strong adsorption of inhibitor 3. The difference in activation energy (Ea) value of 42.4 kJ mol−1 between the control and the inhibited solution indicated an efficient adsorption of inhibitor 3. The ability of inhibitor 3 to retard both anodic and cathodic half-cell reactions was proved via open circuit potential and Tafel curves studies. Detailed discussions on the change in corrosion current densities (icorr), polarization (Rp) and charge transfer (Rct) resistances have been offered to discuss the inhibition efficiency. Water contact angle measurement showed a drastic increase in mild steel surface hydrophobicity following inhibitor 3 adsorption. SEM-EDX and XPS studies confirmed the definitive presence of inhibitor 3 on the mild steel surface. Density functional theory (DFT) studies revealed the frontier molecular orbitals with which the metal surface interacts. A detailed corrosion inhibition mechanism has been offered in the context of adsorption isotherm and DFT studies.

Corrosion potential and theoretical studies of fabricated Schiff base for carbidic austempered ductile iron in 1M H2SO4 solution

In this body of work, a chemical known as 2-cyano-N-(4-morpholino benzyl dine) acetohydrazide (CMBAH) is explored for its ability to suppress the carbidic austempered ductile iron (CADI) corrosion in 1M H2SO4. Density functional theory was used in experiments and theoretical investigations to investigate the inhibiting impact. The corrosion of CADI alloys in 1M H2SO4 produced a corrosion resistance superior to that of CADI heat treatment (H.T.). As-cast carbidic ductile iron (CDI) 4 alloy with 1.5%t Cr-Nb has a corrosion rate (C.R.) of 11.69 mm/year, which drops to 5.31 mm/year at HT-275 °C and 6.13 mm/year at HT-375 °C. When describing the adsorption of inhibitors, the Langmuir adsorption isotherm is the most effective method. The findings of the Gads show that the inhibition was induced mainly by the physisorption on the surface CADI alloys. In addition to this, it was found that the results of the experiments and the hypotheses were largely harmonious with one another. The formation of protective layers on the CADI surfaces is also visible in the images captured by the SEM. In 1M H2SO4, these Schiff base inhibitors effectively prevent corrosion caused by CADI. However, the combination of inhibitors leads to a fine microstructure with ausferrite and narrow ferrite needles, promoting corrosion resistance. The CADI needles rated an upper ausferritic microstructure with wide ferrite needles.

New Benzimidazole derivatives as efficient organic inhibitors of mild steel corrosion in hydrochloric acid medium: Electrochemical, SEM/EDX, MC, and DFT studies

The corrosion of mild steel (MS), a widely used material in industry, represents a significant global challenge. In order to extend the durability of equipment, the use of corrosion inhibitors proves to be an effective solution, particularly in corrosive environments. In this research, two newly synthesized benzimidazole derivatives, namely 1-(cyclohex-1-en-1-yl)-3-[(3-phenyl-1,2-oxazol-5-yl)methyl]-2,3-dihydro-1H-1,3-benzodiazol-2-one (Benz1) and 1-(cyclohex-1-en-1-yl)-3-[(3-phenyl-4, 5-dihydro-1,2-oxazol-5-yl)methyl]-2,3-dihydro-1H-1,3-benzodiazol-2-one (Benz2), were evaluated as corrosion inhibitors for MS in 1 M hydrochloric acid solution. This study was conducted using both experimental methods and computational approaches. Potentiodynamic polarization diagrams (PDP) indicate that, depending on concentration effects, Benz1 and 2 function as mixed-type inhibitors, with a predominance of cathodic inhibition. The results of electrochemical impedance spectroscopy (EIS) show that the compounds tested offer high inhibition efficiencies of 96.32 % and 98.30 % at 10−⁴ M for Benz1 and 2, respectively. Inhibitor adsorption follows the Langmuir isotherm and involves chemisorption. SEM/EDX analyses confirm the presence of a protective film on the metal. In addition, DFT and Monte Carlo simulations reveal significant adsorption of the compounds on the MS surface, underlining their high potential as effective corrosion inhibitors.

Graphene Nanoplatelets Extend Life of Scale-Inhibitor Squeeze Treatment

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215228, “Graphene Nanoplatelets for Extended Lifetime of Scale-Inhibitor Squeeze Treatment in a High-Temperature Reservoir,” by Suzalina Zainal, SPE, Norzafirah Razali, and Mohamad A. Rodzali, Petronas, et al. The paper has not been peer reviewed. _ Scale-inhibitor squeeze (SISQ) treatment is an established method for offshore fields that allows an extended effectiveness of scale inhibitors in preventing deposition over time. One of the primary issues in SISQ campaigns is the short squeeze lifetime of less than 1 year. The study detailed in the complete paper proposed graphene nanoplatelets (GNP) as a preflush system to extend the lifetime of a conventional SISQ treatment. This carbon-based nanomaterial allowed enhanced adsorption of the phosphonate-based scale inhibitor. GNP as a Preflush System A high-surface-area GNP preflush system was chosen to condition the rock surface to overcome the apparent lack of suitable surfaces available for scale-inhibitor adsorption during SISQ treatment. The GNP was injected to coat the rock surface. GNPs consist of a few graphite layers with thicknesses varying from 0.7 to 100 nm. The carbon-based nanomaterial forms a honeycomb structure, regarded as a good alternative to its predecessor, graphene, because of its lower cost and potential for large-scale production. GNP particle size ranges between 100 and 200 nm. This 2D carbon nanomaterial offers several advantages, such as high surface area, a high aspect ratio with a planar shape, and good mechanical properties with excellent thermal and electrical conductivities. It is also inert toward common reservoir fluid. Experimental Procedure Materials. Injection and formation water (brine samples) were prepared based on compositions listed in Table 1 of the complete paper. Berea core plugs were used for static-adsorption and injectivity experiments. In these two experiments, the core samples were used to provide similar rock properties when comparing performances of the baseline preflush (seawater) vs. nano-preflush systems. The average rock permeability for the candidate oil field is between 200 and 400 md. Dispersion Evaluation in High Divalent Brine. Gum arabic (GA) stabilized the GNP in high divalent brine. The polymer-grafted GNP (P-GNP) samples were evaluated in terms of exfoliated sites as compared with GNP alone. Zeta-potential and particle-size analysis also were performed at different P-GNP concentrations. Static-Adsorption Evaluation. A static-adsorption method was designed to replicate preflush injection of P-GNP before introduction of scale inhibitor. Experiments compared the adsorption of the scale inhibitor onto crushed Berea rock, precoated with P-GNP, with another without pre-coating that used seawater preflush only. Coreflood Evaluation. Because of the scarcity of the native core samples, only Berea core samples were used for the injectivity study, while native core samples were used for the SISQ adsorption/desorption coreflood evaluation. In both types of experiments, a P-GNP preflush system was compared with the baseline (seawater preflush).

WITHDRAWN: Moroccan Cannabis sativa L plant extract as green corrosion inhibitor for mild steel in 1 M HCl solution

Cannabis Sativa L Extract (CSLE) action on the electrochemical properties of mild steel in 1M HCl solution was studied, using potentiodynamic polarization and electrochemical impedance spectroscopy. The findings revealed an improvement in corrosion inhibition efficiency when extracts concentrations increase, achieving an inhibitory efficiency of 96.68% at 10% (v/v) of CSLE. Moreover, the temperature influence on the effectiveness of the extract has been studied over a range of 293-338K and findings proved the inhibitor adsorption according to mono-layer barrier film conformed to Langmuir isotherm. Corrosion kinetics and thermodynamic factors were calculated and discussed. Furthermore, the DFT method has been exploited to describe the corrosion inhibitory mechanism.

Exploration of adsorption properties of organic corrosion inhibitors on layered double hydroxide nanosheet: A molecular dynamics simulation study

Understanding the adsorption of organic corrosion inhibitors with different functional groups on layered double hydroxide (LDH) nanosheet is crucial for the synthesis of these protective materials. In this study, the adsorption process of five deprotonated organic corrosion inhibitors—lactate (Lc), 2-hydroxybenzothiazole (2-OH-BTH), 2-mercaptoethanesulfonic acid (MS), N,N-dimethylethanolamine (DMEA), and eugenol (EG)—on LDH nanosheets was simulated. The adsorption rate, adsorption configuration, and adsorption stability between LDH nanosheet and organic corrosion inhibitors were investigated throughout the entire adsorption process. The study observed consistency in the adsorption rate and stability of these organic corrosion inhibitors in the following order: Lc > 2-OH-BTH > MS > DMEA > EG. Additionally, hydrogen bonds between the organic corrosion inhibitors and the LDH nanosheet is the primary mechanism driving adsorption. The number and stability of hydrogen bonds influenced both the adsorption rate and stability. It is noteworthy that 2-OH-BTH and DMEA have not previously been incorporated into LDH. There is potential for these two organic corrosion inhibitors to be modified for LDH, suggesting significant prospects for future research.

Machine learning models and computational simulation techniques for prediction of anti-corrosion properties of novel benzimidazole derivatives

The present paper delves into the development of predictive models for the optimum prediction of inhibition efficiencies and anti-corrosion properties of newly designed benzimidazole compounds in an HCl medium. Density functional theory (DFT) was used to obtain the molecular descriptors. 17 descriptors considered as input variables were reduced to 9 after redundant variables were eliminated using the variance inflation factor (VIF). Machine learning models such as random forest regression (Rf), K-nearest neighbor (KNN), and gradient boosting (GB) were used to develop a predictive model using data from 50 benzimidazole derivatives whose inhibition efficiencies for steel alloy in HCl medium have been determined experimentally and are available in the literature. The cross-validation (CV) technique was used to evaluate the predictive capability of the models. KNN gave the best result with a coefficient of correlation (R2) of 0.654, compared to GB (0.591) and RF (0.512). Subsequently, the three models were used to predict the inhibition efficiencies of three novel benzimidazole compounds. The corrosion inhibition efficiency of three newly developed benzimidazole compounds was 91 % - 98.5 % when assessed with the best-performing model, K-nearest neighbor (KNN) with MSBAH recording the highest value of 98.5 %. Fukui indices parameters fk+k,fk−k,andf2(r) showed that both the electrophilic and nucleophilic sites are concentrated around specific atoms most of whom are heteroatoms that participate actively in electron-donor and acceptor interaction with the metal atom leading to the formation of coordinate covalent bonds. The results of electron distribution and Fukui dual descriptors support the results of the predictive model. The study also revealed that machine learning algorithms in conjunction with DFT and MD simulation is an innovative technique for the prediction of anti-corrosion properties of newly designed molecules such as corrosion inhibition efficiencies, and mechanism of inhibitor adsorption on metal/alloy surfaces exposed to an aggressive environment. This technique can be harnessed in proffering solutions to acid corrosion especially those that occur during descaling operation.

Eco-friendly corrosion inhibitor of Q235 carbon steel in 1.0 M HCl by Isatin/Chitosan Schiff base

This study presents the synthesis of an eco-friendly and green Schiff base, namely Isatin-Cs Schiff base corrosion inhibitor for Q235 carbon steel in 1.0 M HCl corrosion solution. Fourier-transformed infrared FT-IR and 1H NMR was utilized to characterize the prepared Isatin-Cs Schiff base corrosion inhibitor. The inhibition performance in 1.0 M HCl solution was investigated via classic weight loss at various temperatures, potentiodynamic polarization (PPD), and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy SEM, X-ray photoelectron spectroscopy XPS, and water contact angle methods are used to analyze the surface morphology of Q235 carbon steel. The polarization measurements indicate that the corrosion inhibitors act as mixed type. Moreover, the weight loss studies show that the efficiency of inhibitor increases with the concentration of inhibitor to reach a maximum efficiency of 88.4 % with 250 ppm at 25 °C. Nevertheless, increasing temperature has negative effect on the efficiency of the Isatin-Cs inhibitor. The Langmuir isotherm Unveil that Isatin-Cs adsorption on Q235 carbon steel is mediated via physi/chemi-sorption. Based on SEM and XPS analyses Isatin-Cs forms stable protective film on Q235 carbon steel. The DFT results complemented the experiments results, both observed the effectiveness of inhibitor adsorption.

Corrosion inhibition performance and mechanism of triethanolamine-triisopropanolamine rust inhibitor in the simulated concrete pore solution

In this research, aiming to deal with the accelerated corrosion deterioration of steel reinforcement in reinforced concrete in harsh environments, a highly efficient rust inhibitor (triethanolamine (TEA)-triisopropanolamine (TIPA)) (abbreviated as TT), which TEA and TIPA compounded in a ratio 4:6, was proposed. The synergistic rust inhibition effect of TEA and TIPA on steel in the simulated concrete pore solution (SCPS), and its corrosion inhibition performance were investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), dry and wet cycling, and scanning electron microscopy (SEM) measurements. The results showed that TT inhibitor could obviously inhibit the corrosion of steel in the SCPS and could inhibit both cathode and anode. The electrochemical corrosion inhibition performance was the most excellent at the dosage of 1.0 %, and the maximum corrosion inhibition efficiency (η1) reached 95.39 %. After 150 times of dry and wet cycling, the percentage of the corrosion area (S), and corrosion inhibition efficiency (η2) with 1.0 % TT inhibitor were 9.3 % and 84.03 %, respectively, and the mass loss rate (M) decreased by 68.4 %, indicating a better rust inhibition performance. The adsorption of the TT inhibitor conformed to the Langmuir adsorption isotherm and inhibited the corrosion of steel by forming a protective film on steel surface through physicochemical adsorption. This study is of great significance to provide new perspectives and improvement measures to build up the deterioration and extend the service life of reinforced concrete in harsh environments.

Shielding against erosion: Exploring the effectiveness of pre-erosion surface corrosion inhibitors

This study investigates the corrosion inhibition effect and adsorption process of two imidazoline corrosion inhibitors, HEIE and TDEI, on pre-eroded X65 steel surfaces. Analysis of weight loss and electrochemical measurements suggests that the irregular structure of pre-eroded surfaces may impede the uniform adsorption of corrosion inhibitors, resulting in reduced effectiveness pre-erosion. Particularly, at a 30° angle of pre-erosion, corrosion inhibition efficacy is observed to be at its lowest. The corrosion inhibition rates of HEIE and TDEI on X65 steel surfaces are found to be 11.9 % lower under pre-eroded conditions at a 30° angle compared to non-eroded surfaces at the same angle. Molecular dynamics (MD) simulations support these findings, indicating that TDEI exhibits lower energy bandgap values and more negative adsorption energies (Eads) compared to HEIE, aligning with experimental results. Moreover, TDEI demonstrates a smaller diffusion coefficient for corrosive agents than HEIE, suggesting stronger adsorption efficiency and a more pronounced protective effect. Study of the corrosion inhibition effect on pre-eroded surfaces provides new ideas and methods for improving protective measures.

Rational utilization of the size and electronic effect of inhibitors enabling high polishing rate with minimum corrosion in copper chemical mechanical polishing

Chemical mechanical polishing (CMP) relies on corrosion to remove excess materials, while also on corrosion inhibitors to ensure post-polished surface quality. The robust adsorption of inhibitors onto metal surfaces typically improves inhibition effectiveness but significantly reduces the polishing rate. In this study, we propose and validate a novel strategy that focuses on the utilization of large-sized physisorption-type inhibitors to address this inherent conflict. By incorporating disproportionated rosin (DR) as the inhibitor, the developed slurry facilely obtained a balance between polishing efficiency and quality for copper CMP. The inhibition mechanism of DR was elucidated through electrochemical characterization, adsorption isotherms, and reactive forcefield molecular dynamics (ReaxFF MD) simulations. The weak physisorption of the inhibitors facilitated their easy removal, resulting in minimal impact on the polishing rate. Additionally, the large-size structure of DR effectively hindered corrosive substances from reaching concave areas not under external force, thereby demonstrating superior inhibition efficacy. The adsorption mode of DR on copper was simultaneously determined through adsorption isotherms and ReaxFF MD simulations, marking the first instance of linking classic adsorption theory with MD simulations. The advantage of the ReaxFF MD simulations over classic MD simulations and density-functional-theory calculations for the metal-inhibitor adsorption systems was also discussed and demonstrated.

Menadione sodium bisulfite as an efficient anti-corrosion additive for mild steel in acid corrosion: Electrochemical, surface morphological and theoretical studies

The corrosion inhibition behavior of Menadione Sodium Bisulfite (MSB) in 1.0 M HCl medium was evaluated using weight loss, electrochemical techniques (Tafel polarisation and Electrochemical impedance spectra), surface analysis (SEM and EDX), Density Functional Theory (DFT), Noncovalent interaction- Reduced Density Gradient (NCI-RDG) and Monte Carlo (MC) simulation techniques. Weight loss measurement showed that as inhibitor concentration increased, the corrosion rate decreased which means that a protective film formed on the metal surface. At 300 ppm, the inhibitor showed a maximum inhibition efficiency of 89.7 %. Tafel polarisation studies indicate that the inhibitor is mixed-type in nature. The inhibitor adsorption on the mild steel is the best fit for the Langmuir isotherm model. As the weak interaction of sodium and oxygen in the inhibitor molecules, the inhibitor exhibits two distinct equilibrium behaviors. (i) inhibitor with sodium (solid-state) and inhibitor without sodium (in liquid-state). These two behaviors were theoretically investigated using DFT and MD simulation studies. The inhibitor and metal interaction is further supported using these theoretical studies. The electron population of the inhibitor was analyzed using molecular electrostatic potential, NCI-RDG, Fukui function, and natural bond orbital analysis. These studies further give an understating of the inhibitor and metal interactions.

Construction of Smart Coatings Containing Core-Shell Nanofibers with Self-Healing and Active Corrosion Protection.

With increasingly severe metal corrosion, coating preparation with high-performance corrosion protection has attracted more attention. Herein, the encapsulation of the corrosion inhibitor 8-hydroxyquinoline (8-HQ) as well as the self-healing agent linseed oil (LO) in polyvinyl alcohol (PVA) and chitosan (CS) shells were realized by coaxial electrospinning, which was recorded as PVA/CS@LO/8-HQ core-shell nanofibers. PVA/CS@LO/8-HQ nanofibers were employed to promote the high-performance corrosion protection of the epoxy coating. The anticorrosion mechanism was that the change of the local pH on the metal surface stimulated the release of 8-HQ from the nanofibers, which were then chelated with iron ions to form a complex. When cracks occurred and caused rupture of the nanofibers, LO was released and reacted with oxygen to cure them so that the cracks could be healed autonomously. The dynamic potential polarization curves showed that the corrosion inhibition efficiency of the compound inhibitor LO + 8-HQ reached 87.54%, 90.31%, and 85.57% at pH = 3, 7, and 11, respectively, higher than that of the single corrosion inhibitor. Density functional theory calculations revealed that the LO and 8-HQ combination, forming a hydrogen bond interaction, promoted the adsorption of inhibitors on the steel surface. Scanning Kelvin probe and electrochemical impedance spectroscopy proved the self-healing corrosion protection properties of the epoxy coating. These results demonstrated that embedding PVA/CS@LO/8-HQ nanofibers in the coating could obtain self-healing properties, and promote the mechanical and corrosion protection of epoxy coating.

Exploring copper corrosion inhibition in value added neem biodiesel: Evaluation by traditional and machine learning approaches

Neem seed biodiesel is an eco-friendly fuel, however, to minimize its corrosion on copper metal used in engine parts, ethyl acetate extract of Syzygium aromaticum flowers was tested as an inhibitor. Copper corrosion evaluation in biodiesel revealed an inhibition efficiency of 97.96 %. Corrosion at the operating temperature of diesel engine was predicted by machine learning - quadratic regression. Thermodynamics and spectral evaluations bring to light the adsorption of inhibitors on the metal surface for inhibiting the corrosion of copper metal immersed in biodiesel. Surface morphological studies revealed the protective nature of the copper metal corrosion. Quadratic Surface Vector Machine (SVM) algorithm classified the corrosion classes as low, medium, and high with an overall accuracy value of 94.6 %. The percentage of non-corroded area of copper metal specimen in biodiesel medium with the said inhibitor as estimated with quadratic SVM is 97.193 %. The research findings suggest that the ethyl acetate extract of S. aromaticum flowers has the potential to perform as an effective corrosion inhibitor for copper in biodiesel medium and revealed the potential of quadratic SVM machine learning algorithm in corrosion estimation and classification.

Electrochemical behavior and theoretical studies of arylazo (1-naphthyl-2-cyanoacetamide) derivatives as new corrosion inhibitors for Inconel 800 in chloride solution

In this study, synthesize and insight the corrosion inhibition properties of two novel derivatives of 1-naphthyl-2-cyanoacetamide (NCDs) [2-cyano-2-((5,6-dimethyl-1H-benzo[d]imidazol-2-yl) diazenyl)-N (naphthalene-1-yl)acetamide] (NCD1) and [2-Cyano-N-(naphthalene-1-yl)-2-[(4,6-dimethyl-1H-pyrazolo [3, 4-b] pyridine-3-yl) hydrazono] acetamide] (NCD2). The characterization of the synthesized NCDs was confirmed through the utilization of Mass fragmentation analysis, 1H-NMR, and IR. The corrosion inhibition performance of NCDs as a novel and environmentally safe corrosion inhibitor has been investigated by electrochemical techniques, a chemical technique, and theoretical studies for its anti-corrosion behavior of Inconel 800 in chloride medium. In addition, the surface morphology and inhibitor adsorption on the Inconel 800 surface were confirmed utilizing SEM, EDX, FTIR, and AFM. The advantages of NCDs include their low toxicity, environmental friendliness, ease of preparation, low odor, contain (N, O, and π-Bonds), and the inhibition efficiency elevated with decreasing solution temperature as well as inhibitor dose increase, yielding increased efficiencies of 91.8% and 95.7% for NCD1 and NCD2, respectively, at the optimum concentration of 21 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 10–6 mol. L−1 and 298 K temperature. An analysis of Tafel plots reveals that NCDs adhere to a mixed and isothermal Langmuir adsorption mechanism. Density Functional Theory (DFT) and Monte Carlo (MC) simulation manifest the two compounds of NCDs can be adsorbed at the Fe (110) surface in a paralleled way, and can have a smaller energy gap (ΔE) value and exhibit higher efficiency. The experimental and theoretical findings confirm that the synthesized compounds obtained are capable of protecting the Inconel 800 from corrosion by creating an anti-corrosion coating on the surface.

Understanding the adsorption of imidazole corrosion inhibitor at the copper/water interface by ab initio molecular dynamics

Understanding the adsorption mechanisms of organic corrosion inhibitors at metal/water interfaces is crucial for designing corrosion inhibitors. Imidazole adsorption at copper/water surfaces was investigated via ab initio molecular dynamics simulations. The adsorption energy of imidazole on copper in water is slightly more positive than that in vacuum, which is attributed to the hydrogen bond interaction between imidazole and water molecules. Imidazole adsorption changes interfacial water density and dipole distribution, disrupts hydrogen bond networks, and decreases water residence time at the interface. These characteristics are considered to be correlated to the decreased corrosion rate induced by imidazole adsorption.