Corrosion Inhibition Mechanism Research Articles

3,4-Dimethoxy phenyl thiosemicarbazone as an effective corrosion inhibitor of copper under acidic solution: comprehensive experimental, characterization and theoretical investigations.

This study investigates the corrosion inhibition potential of 3,4-dimethoxy phenyl thiosemicarbazone (DMPTS) for copper in 1 M hydrochloric acid (HCl) solutions, aiming to disclose the mechanism behind its protective action. Through an integrative methodology encompassing electrochemical analyses-such as weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS)-we quantitatively evaluate the corrosion protection efficacy of DMPTS. It was determined that the optimal concentration of DMPTS markedly boosts the corrosion resistance of copper, achieving an impressive inhibition efficiency of up to 89% at 400 ppm. The formation of a protective layer on the copper surface, a critical aspect of DMPTS's inhibitory action, was characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). These techniques provided empirical evidence of surface morphology modifications and roughness changes, affirming the formation of a protective barrier against corrosion. A significant advancement in our study was the application of Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, which identified chemical adsorption as the definitive mechanism of corrosion inhibition by DMPTS. The ATR-FTIR results explicitly demonstrated the specific interactions between DMPTS molecules and the copper surface, indicative of a robust protective adsorbed layer formation. This mechanistic insight, crucial to understanding the inhibitory process, aligns with the protective efficacy observed in electrochemical and surface analyses. Theoretical support, provided by the Quantum Theory of Atoms in Molecules (QTAIM) and quantum chemical computations, further validated the strong molecular interaction between DMPTS and copper, corroborating the experimental findings. Collectively, this research not only confirms the superior corrosion inhibition performance of DMPTS in an acidic setting but also elucidates the chemical adsorption mechanism as the foundation of its action, offering valuable insights for the development of effective corrosion inhibitors in industrial applications.

Cellulose, cellulose derivatives and cellulose composites in sustainable corrosion protection: challenges and opportunities.

The use of cellulose-based compounds in coating and aqueous phase corrosion prevention is becoming more popular because they provide excellent protection and satisfy the requirements of green chemistry and sustainable development. Cellulose derivatives, primarily carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC), are widely employed in corrosion prevention. They function as efficient inhibitors by adhering to the metal's surface and creating a corrosion-inhibitive barrier by binding using their -OH groups. Their inhibition efficiency (%IE) depends upon various factors, including their concentration, temperature, chemical composition, the nature of the metal/electrolyte and availability of synergists (X-, Zn2+, surfactants and polymers). Cellulose derivatives also possess potential applications in anticorrosive coatings as they prevent corrosive species from penetrating and encourage adhesion and cohesion, guaranteeing the metal substrate underneath long-term protection. The current review article outlines the developments made in the past and present to prevent corrosion in both the coating phase and solution by using cellulose derivatives. Together with examining the difficulties of the present and the prospects for the future, the corrosion inhibition mechanism of cellulose derivatives in the solution and coating phases has also been investigated.

The inhibition effect of 1, 3-diazole glyoxaline on corrosion of API 5L X52 pipeline steel in oilfield produced water under sweet corrosive conditions

Corrosion induced by aqueous environments containing carbon dioxide (CO2) is a well-documented issue in the oil and gas industries, particularly affecting transportation via steel pipelines. Operational conditions during transportation, including temperature, flow rate, and solution chemistry, significantly influence the corrosion inhibition mechanism. In this study, the corrosion inhibition behavior of API 5L X52 steel in a 3.5 wt% NaCl brine solution saturated with carbon dioxide was investigated using 1, 3-diazole glyoxaline (DG) as an organic inhibitor. Both gravimetric and electrochemical methods were employed to assess corrosion rates and inhibitor efficiency across various temperatures, inhibitor concentrations, and rotational speeds. The outcomes showed that inhibition efficiency increased with inhibitor concentration and temperature. From weight loss measurements, the maximum inhibition efficiency was 98.58 % at 3 × 10−4 M of DG and 60 °C. The polarization investigations showed a reduction in the anodic and cathodic curves in the presence of the inhibitor. This suggested a mixed-type inhibition mechanism. The electrochemical impedance spectroscopy results showed an improvement in charge transfer resistance due to the formation of a protective layer on the metal surface. In addition, AFM, SEM, contact angle, hardness, and roughness measurements proved the enhancement in surface morphology due to the presence of DG.

Bishydrazone ligand and its Zn-complex: synthesis, characterization and estimation of scalability inhibition mitigation effectiveness for API 5L X70 carbon steel in 3.5% NaCl solutions.

Bishydrazone ligand, 2,2'-thiobis(N'-((E)-thiophen-2-ylmethylene) acetohydrazide), H2TTAH and its Zn- complex were prepared and characterized through elemental analysis and various spectroscopic performances as well as (IR, 1H and 13C NMR, mass and (UV-Vis) measurements. The synthesized complex exhibited the molecular formula [Zn2(H2TTAH)(OH)4(C5H5N)3C2H5OH] (Zn-H2TTAH). To assess their potential as anti-corrosion materials, the synthesized particles were assessed for their effectiveness for API 5L X70 C-steel corrosion in a 3.5% NaCl solution using electrochemical methods such as potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Additionally, X-ray photoelectron spectroscopy (XPS) was employed to examine the steel surface treated with the tested inhibitors, confirming the establishment of an adsorbed protecting layer. The results obtained from the PP plots indicated that both H2TTAH and Zn-H2TTAH act as mixed-type inhibitors. At a maximum concentration of 1 × 10-4 M, H2TTAH and Zn-H2TTAH exhibited inhibition efficiencies of 93.4% and 96.1%, respectively. The adsorption of these inhibitors on the steel surface followed the Langmuir adsorption isotherm, and it was determined to be chemisorption. DFT calculations were achieved to regulate the electron donation ability of H2TTAH and Zn-H2TTAH molecules. Additionally, Monte Carlo (MC) simulations were conducted to validate the adsorption configurations on the steel surface and gain insight into the corrosion inhibition mechanism facilitated by these molecules.

Preparation and corrosion inhibition mechanism of a chitosan ionic liquid Schiff base for the protection of N80 in HCl solution

Three chitosan ionic liquid type Schiff bases (CS-IL-SBs) were synthesized by grafting three aldehydes (vanillin, cinnamaldehyde, and pyridine-4-carboxaldehyde) on CS-IL (chitosan grafted with p-toluene sulfonic acid) through a Schiff base reaction.

Synergistic inhibitive effect of a hybrid zinc oxide-benzalkonium chloride composite on the corrosion of carbon steel in a sulfuric acidic solution

Abstract Zinc oxide and quaternary ammonium-type surfactants have been separately recognized for their anti-corrosive efficiencies. Their composite, not investigated so far, could provide a synergetic anti-corrosion effect. In this respect, the aim of this study is to synthesize a composite material consisting of zinc oxide and benzalkonium chloride (ZnO-BAC) in varying mass ratios (3:1, 1:1, and 1:3). The inhibitory properties of the ZnO-BAC composite against carbon steel corrosion in a 0.5 M sulfuric acid solution were assessed under ambient conditions. First, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to examine the chemical structure of the prepared composite. Then, the corrosion inhibitive performance of the devised inhibitors was screened using electrochemical, hydrogen collection, and weight loss measurements. Further, the surface morphology was examined using a scanning electron microscope, both before and after immersion in the corrosion medium. The electrochemical measurements indicate that the prepared inhibitor exhibits a predominant cathodic inhibition behavior and the maximum inhibition efficiency, approximately 91.9%, was achieved for one-to-one mass ratio. Similar results were obtained from weight loss and hydrogen evolution measurements, which showed that the ZnO-BAC composite reduced the corrosion rate of carbon steel by 69.9% and 64.9%, respectively. Finally, molecular dynamics and an adsorption equilibrium model were used to elucidate the mechanism of corrosion inhibition by the ZnO-BAC composite, which exhibits a high adsorption energy on the iron surface.

The use of LDHs-NO3- and LDHs-NO2- as corrosion inhibitors in simulated concrete pore solution: An experimental and theoretical study

To further reveal the mechanism of LDHs-NO3- and LDHs-NO2- against chloride attack in simulated concrete pore solution, this paper comparatively investigated their effects on the corrosion inhibition efficiency in the presence/absence of OH- via experiments and DFT simulations. The synthetic LDHs-NO3- and LDHs-NO2- were characterized using an X-ray diffractometer and Fourier infrared spectroscopy. Electrochemical tests including open circuit potential, electrochemical impedance spectroscopy and linear polarization resistance were performed. The adsorption amount of Cl- in LDHs was determined. The DFT calculations were conducted to explore the interactions between the ions and LDHs and inhibitors and iron surfaces, respectively. The results show that in the absence of OH-, NO2- easily released from LDHs due to the higher difference in the bond length of NN2-HL and ON2-HL, and LDHs-NO2- could adsorb higher content of Cl- compared to LDHs-NO3-. In the presence of OH-, LDHs-NO2- had better against Cl- corrosion. The bond between NO3- or NO2- and LDHs was weakened, resulting in an easy release of NO3- or NO2-. However, the adsorption amount of Cl- was reduced in LDHs due to the competitive adsorption between Cl- and OH-. The adsorptions of NO3- and NO2- on the iron surface were primarily through the Fe-N and Fe-O bonds, where the Fe-NO2- surface was more stable. The increased Eads values could cause the desorption of Cl- on the iron surface. Thus, OH- could enhance the adsorption of NO3- and NO2- and further promote the desorption of Cl- on the iron surface. This research would provide fundamental insight into the corrosion inhibition mechanisms of LDHs in simulated concrete pore solution.

Effect of LDHs-ALA on steel corrosion in chloride-rich simulated concrete pore solution: experimental and DFT studies

Seeking green and efficient anti-rust anion is beneficial to promote the development and application of layered double hydroxides (LDHs) corrosion inhibitor. This paper explores the feasibility of alanine (ALA) as interlayer anion of LDHs and the corrosion inhibition mechanism of LDHs-ALA via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), electrochemical tests, chloride equilibrium isotherm, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) simulations. The results show that LDHs-ALA can be synthesized using calcination-rehydration method. The binding energy (EB) of LDHs-ALA is more positive than that of LDHs-Cl, implying chloride ion can be captured by LDHs-ALA. The chloride capture behavior of LDHs-ALA conforms to the Langmuir isotherm as following equation: qe=0.073Ce/(1+0.02Ce). The released ALA- can be adsorbed on Fe (100) surface and increase the Fe2+/Fe3+ ratio of passive film by forming Fe-O bond. Moreover, the pre-adsorption of ALA- on Fe (100) surface weakens the interaction between Cl 3p orbital and Fe 3d orbital, increasing the adsorption energy of Cl- on the Fe (100) surface and lengthening the Fe-Cl bond. Therefore, LDHs-ALA has a high inhibition efficiency up to 99.7%.

Pulse electrodeposition of a duplex-layer structured composite nickel-based coating with improved corrosion and abrasion resistance

In this study, a dual amorphous/crystalline nanocomposite coating of Ni–P/Ni–Mo–ZrO2 was designed and successfully deposited on pure copper substrates by pulse electrodeposition. The design of the Ni–P/Ni–Mo–ZrO2 dual coating takes advantage of the properties of the different structures and incorporates second phase reinforcing particles resulting in more comprehensive protective coatings. The surface morphology and microstructure were evaluated by SEM, EDS, WLI, XRD and TEM. The mechanical properties and electrochemical behaviors of the coating in a 3.5 wt% NaCl solution were investigated by wear tests, Tafel and EIS. The results show that the Ni–P/Ni–Mo and Ni–P/Ni–Mo–ZrO2 dual coatings are uniform, dense and crack-free, and the duplex interface is homogeneous. Compared with the Ni–Mo coating, the average friction coefficient and wear rate of the Ni–P/Ni–Mo duplex coating decreased to 0.18 and 5.433 × 10−4 mm3/N·m, respectively. The corrosion potential is positively shifted to −0.43 with a maximum impedance of 308 kΩ cm2. The mismatch of the interlayer defects causes a deviation in the corrosion path, resulting in a transformation from longitudinal pinhole corrosion into extended transverse corrosion, which effectively strengthens the capacity of the coating for corrosion resistance while maintaining the high hardness of its outer coating. Furthermore, the hardness of the dual Ni–P/Ni–Mo coating can be obviously reinforced by nanoparticles from 730 HV to 810 HV, the corrosion potential is shifted to −0.41 V, and the corrosion current density decrease to 7.7803 × 10−7 A/cm2. The improvement in the mechanical properties can be attributed to the ZrO2 nanoparticles, which could carry stress and transfer loads during the wear process. Meanwhile, the ZrO2 nanoparticles can reduce the nodule size by filling the binding boundary which is the main corrosion path, and reduce the number of surface defects, such as pinholes, which leads to a lower corrosion rate. In addition, the corrosion inhibition and nanoparticle codeposition mechanisms of the duplex coatings were further discussed.

Efficient and long-lasting corrosion inhibition mechanism of an anionic surfactant on AZ91D Mg alloy in oxalic acid solution

The efficient and long-lasting corrosion inhibition mechanism of bis(2-ethylhexyl) sulfosuccinate sodium (AOT) on AZ91D Mg alloy in oxalic acid solution were studied by electrochemical methods, surface techniques, theoretical calculations and simulations. The findings demonstrated that AOT was an effective and long-lasting corrosion inhibitor, the corrosion inhibition rate of 6.75 mM AOT was 89.84 % and raised in corrosion inhibition effectiveness with increasing soaking duration. The adsorption of AOT followed Langmuir adsorption isotherm and belonged to physical and chemical mixed adsorption. The polar sulfonyl group of AOT gradually almost vertically adsorbed on its surface to produce a uniform, dense, and thick protective layer to inhibit its corrosion, and the hydrophobicity of the alkyl chain of AOT repelled corrosive medium.

Experimental and computational aspects of green corrosion inhibition for low carbon steel in HCl environment using extract of Chamaerops humilis fruit waste

The inhibition effect of a methanolic extract of Chamaerops humilis (CHFE) on the corrosion of low-carbon steel in 1 M HCl solution was evaluated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy. The extract was obtained from the fruit seeds by the Soxhlet extraction method. The CHFE demonstrated promising anticorrosive performance, and the inhibition efficiency increased with increasing the concentration of the extract, peaking at 93% at only 500 ppm. Importantly, the inhibitor exhibited a remarkable stability after 48 h of immersion, reaching an efficiency of 94%. The extract revealed a mixed-type inhibitive behavior. In addition, elevating the solution temperature showed a negative influence on the inhibition efficacy. Thermodynamic parameters suggested that the steel dissolution is an endothermic, spontaneous process. In addition, the experimental findings match well with the Langmuir adsorption isotherm and physisorption of the extract prevails. Furthermore, SEM/EDX and UV-Vis analyses demonstrated that the steel surface is protected by the extract molecules, confirming the electrochemical results. Density functional theory (DFT), Fukui function and molecular dynamics (MD) calculations unraveled the nature of inhibitor—metal surface interactions and provided insights into the most favorable electrophilic and nucleophilic active sites of oleic acid, a major constituent of the extract, helping to elucidate the mechanism of corrosion inhibition at the molecular level.

Chemistry of the interaction between Imidazole derivatives as corrosion inhibitors molecules and copper/brass/zinc surfaces: A DFT, reactive and classical molecular force fields study

In the present research, we explored the corrosion inhibition mechanisms on metals and alloys by imidazole, methylimidazole, and benzimidazole applying density functional theory (DFT), reactive (ReaxFF), and classical force fields. Our investigation focused on the interaction of these molecules with different types of bare metal surfaces. The results of our studies have been compiled to compare the protection efficiency of the three organic molecules for copper, zinc, and copper-zinc alloys (Cu63%-Zn37%) exposed to the same corrosion conditions in an acid environment. The calculated interaction energy quantities are strongly correlated with the experimental corrosion inhibition efficiencies BIM > MIM > IM. The imidazole derivative studied, significantly better protect copper than zinc, which is attributed to the higher bond strength of Cu–N (formation of chemical bonds) than of Zn–N, confirms the increase in the protection effectiveness against corrosion of Zn < Cu63%-Zn37% < Cu. This present study demonstrates the enormous potential of ReaxFF calculations to accurately simulate the adsorption of inhibitor molecules onto metal surfaces at a fraction of the computational cost of DFT, as well as the performance of the umbrella sampling method to assess the adsorption free energies.

The effect of pre-corrosion on corrosion inhibition performance and mechanism of quinoline quaternary ammonium salts

The influence of pre-corrosion on the corrosion inhibition performance and corrosion inhibition mechanism of quinoline quaternary ammonium salt (QQAS) on Q235 carbon steel in 1 wt% HCl solution at 60 °C were investigated by weight loss experiment, molecular dynamics simulation. The results of IR vibrational spectra and NMR hydrogen spectra indicate the successful synthesis of QQAS. The results of weight loss experiments show that the corrosion inhibition performance of the synthesized QQAS increase with the increasing of the concentration under the condition of Q235 carbon steel with and without pre-corrosion. But the pre-corrosion obviously decreases the corrosion inhibition efficiency by 17.28% when the concentration is 50 mg·L−1. Analysis of thermodynamic parameters shows that the adsorption of QQAS on the steel surface is a spontaneous and exothermic process, which conforms to the Langmuir isothermal formula and is mainly based on chemical adsorption. The results of molecular dynamics simulation indicate that pre-corrosion changes the equilibrium adsorption conformations of QQAS molecules, and decreases the adsorption energies, and decreases the density of the film for the different oxidization extent of Q235 carbon steel. As a result, the corrosion inhibition performance of QQAS is decreased by the pre-corrosion. The results are in good agreement with the results of weight loss experiments. The corrosion inhibition performance of QQAS is the best when the number of QQAS molecules is 18. The corrosion inhibition mechanism is a single molecular layer adsorption mechanism. The results of this study can provide a reference for studying the corrosion inhibition performance and corrosion inhibition mechanism of corrosion inhibitors under the action of pre-corrosion.

Morphological performances and corrosion inhibition mechanism of new amphiphilic tetra-cationic imidazolium ionic liquids for carbon steel in 1M HCl medium

BackgroundRoom temperature liquids based on amphiphilic imidazolium ionic liquids (AImILs) with superior surface properties in acidic aqueous solutions form stable thin film on the surface of steel attracted great attention to apply as green corrosion inhibitors at different temperatures. MethodsTetra-cationic ionic liquids 2-(4-dodecyldimethylamino) phenyl)-1,3-bis (3-dodecyldimethylammnonio) propyl) bromide-1-H-imidazol-3-ium acetate (DDAP-ImA) and 2-(4-hexyldimethylamino) phenyl)-1,3-bis(3-hexcyldimethylammnonio) propyl) bromide-1 H-imidazol-3-ium acetate (HDAP-ImA) were prepared with higher reaction yields using two steps technique. The corrosion inhibition efficiencies of the prepared ImILs for steel surface in 1 M HCl were evaluated at different temperature using different techniques. Significant findingsThe data confirm that lower concentrations of DDAP-ImA achieved higher corrosion inhibition efficiencies based on physio-chemical mechanism on the steel surface with the formation of linked and adsorbed layers on the steel surfaces even at lower concentrations that confirmed from the standard free energy. Surface morphologies (SEM, AFM) indicated that more homogeneous surface and metallic interfaces in the presence of HDAP-ImA and DDAP-ImA were formed more than blank and in the presence of DPAP-ImA. This protective homogeneous film limits the transfer of active corrosive species towards the steel surface which was rationalized in an inhibition mechanism.

A novel effective carbon dots-based inhibitor for carbon steel against chloride corrosion: From inhibition behavior to mechanism

Reinforced concrete (RC) structures suffer from serious chloride corrosion. Corrosion inhibitors can effectively protect reinforcement against chloride corrosion, thus improving the durability of RC structures. Benefiting from their environmental friendliness, simple preparation, and high inhibition efficiency, carbon dots (CDs) as a promising green corrosion inhibitor have attracted intensive attention. However, there is no investigation on the corrosion inhibition performance and mechanism of CDs in a chloride-contaminated alkaline medium for carbon steel, thereby hindering their application in RC structures. In the current research, CDs as a novel effective corrosion inhibitor were first applied to protect carbon steel in a chloride-contaminated simulated concrete pore solution (Cl-SCPS). Specifically, their inhibition behavior was investigated using electrochemical impedance spectra and potentiodynamic polarization measurements; And the inhibition mechanism was revealed by adsorption isotherm analysis, corrosion morphology study, and theoretical calculation. Results showed that CDs could achieve long-term inhibition efficiency of 99.2 % only at 400 mg/L on carbon steel in Cl-SCPS. Notably, the inhibition mechanism of CDs was ascribed to their stable adsorption on Fe (110) or γ-FeOOH (010) surfaces of carbon steel, with significantly higher Ebinding absolute values compared to previous literature. This research provided a novel high-performance inhibitor, as well as the facile synthesis method, to effectively mitigate chloride corrosion of carbon steel, expected to improve the durability of RC structures.

High-temperature corrosion of phosphate completion fluid and corrosion inhibition method by membrane transformation

By analyzing the corrosion of phosphate completion fluid on the P110 steel at 170 °C, the high-temperature corrosion mechanism of phosphate completion fluid was revealed, and a corrosion inhibition method by membrane transformation was proposed and an efficient membrane-forming agent was selected. Scanning electron microscope (SEM) images, X-ray energy spectrum and X-ray diffraction results were used to characterize the microscopic morphology, elemental composition and phase composition of the precipitation membrane on the surface of the test piece. The effect and mechanism of corrosion inhibition by membrane transformation were clarified. The phosphate completion fluid eroded the test piece by high-temperature water vapor and its hydrolyzed products to form a membrane of iron phosphate corrosion product. By changing the corrosion reaction path, the Zn2+ membrane-forming agent could generate KZnPO4 precipitation membrane with high temperature resistance, uniform thickness and tight crystal packing on the surface of the test piece, which could inhibit the corrosion of the test piece, with efficiency up to 69.63%. The Cu2+ membrane-forming agent electrochemically reacted with Fe to precipitate trace elemental Cu on the surface of the test piece, thus forming a protective membrane, which could inhibit metal corrosion, with efficiency up to 96.64%, but the wear resistance was poor. After combining 0.05% Cu2+ and 0.25% Zn2+, a composite protective membrane of KZnPO4 crystal and elemental Cu was formed on the surface of the test piece. The corrosion inhibition efficiency reached 93.03%, which ensured the high corrosion inhibition efficiency and generated a precipitation membrane resistant to temperature and wear.

Study on corrosion inhibition performance and mechanism of quinoline quaternary ammonium salt and l-methionine on pre-corrosion Q235 steel

Abstract The corrosion inhibition properties and mechanisms of quinoline quaternary ammonium salt (QA) and L-methionine (LM) on pre-corroded Q235 carbon steel in 1wt% HCl solution were studied using the weight loss method and molecular simulation technology. The degree of pre-corrosion of steel will affect the corrosion inhibition performance of the corrosion inhibitor. QA and LM compete to adsorb to the iron surface to form a film, and the repulsion between the corrosion product and the film reduces the slow-release performance.

Comprehensive investigation of sustainable corrosion inhibitors on Cu–Zn alloy in simulated cooling water: Electrochemical explorations, SEM/EDX analysis, and DFT/molecular simulations utilizing expired Bepotastine-B as a green inhibitor

In terms of green chemistry, the use of the use of expired drugs has recently gained attention as sustainable corrosion inhibitors due to their biodegradability, environmental friendliness, low cost, and easy availability. This paper aimed to evaluate the protective action of expired Bepotastine-B on Cu–Zn alloy in simulated cooling water (SCW) using weight loss (WL), Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), surface morphology analysis and computer modeling methods, including density functional theory (DFT) and molecular dynamic simulations (MS).The variables concentration, reaction temperature, and pH of an expired drug were examined. The electrochemical results demonstrated that the expired Bepotastine-B is a mixed-type inhibitor that blocks both the anodic and cathodic potentials, which exhibited high inhibition. The corrosion rate falls as the Bepotastine increases and increases as the temperature rises. The drug's adsorption on Cu–Zn alloy follows the Langmuir isotherm model. The examination of surface morphology (SEM/EDX) indicated a formation of an insoluble complex and a fine film of inhibitor, which effectively hinders Cu–Zn alloys from deteriorating, covering the surface. These findings confirmed the formation of an adsorbed layer by the Bepotastine-B molecules hindered the dissolving of Cu–Zn alloys. The inhibitory impact of Bepotastine-B, which investigated, theoretically using DFT and the computational results align well with the results obtained from experimental inhibition efficiencies. The inhibition efficiency (IE) improved with raising Bepotastine-B concentration. The maximum IE of 94.6% has been achieved at 300 mg/L. The combination of experimental and computational approaches enhanced our understanding of the corrosion inhibition mechanism and underscored the potential of Bepotastine-B as a sustainable, and effective corrosion inhibitor for Cu–Zn alloy in this medium at dissimilar temperatures. These findings can serve as a useful guideline for future research aimed at investigating the inhibitory impact of expired drugs as a green one.

Elucidating the corrosion inhibition mechanisms: A computational and statistical exploration of the molecular structure-efficiency relationship for phenolic Schiff bases in acidic medium on the mild steel surface

This study investigated mild steel corrosion inhibition using four Schiff bases in a theoretical framework. The study used statistical analysis to relate the experimental inhibitor's efficacy to theoretical data, revealing the corrosion inhibition process. Density functional theory (DFT) was used to assess the global reactivity of the four inhibitors' neutral, protonated, and complex forms. Where, Fukui functions were used for local reactivity study of the four inhibitors in neutral and protonated forms. To study system dynamics at the inhibitor-steel contact, a Monte Carlo simulation was performed. The experimental and quantum results are strongly correlated when the global quantum features of the neutral and protonated forms, such as the dipole moment μ, EHOMO, and ELUMO, are examined. The PA and pKa protonation parameters demonstrate that the protonation of the compounds strongly influences the inhibition efficiency. According to Fukui functions, the amine function (N) is the highest nucleophilic reactivity, making it highly sensitive to electrophilic attack, for all four inhibitors. The stability and predominance of complex forms in the medium were interpreted using thermodynamic characteristics of PSBi-FeCl2 complexes. Monte Carlo simulation yielded the most stable adsorption configurations, which were geometrically and energetically examined to explain experimental data. QSAR shows a significant linearity between theoretical parameters and experimental inhibitory efficiency.

Structure-performance relations of thio-alcohols and their synergistic corrosion inhibition for carbon steel in CO2-saturated solution

Corrosion of carbon steel in CO2-containing brine solutions is a major issue in the oil and gas industry. In this study, comparison of different structure thio-alcohols, dithiothreitol (DTT) and mercaptoethanol (ME), in synergism with oleic imidazoline (IM) for inhibiting corrosion of carbon steel in CO2-saturated oil/brine solution was investigated. The corrosion inhibition effect and mechanism of the mixed corrosion inhibitors (IM-DTT and IM-ME) were assessed using weight loss, electrochemical techniques, surface characterizations and theoretical simulations. The results demonstrate that DTT have better synergism with IM than that of ME in corrosion inhibition. IM-DTT is co-adsorbed forms a highly hydrophobic inhibition film on the specimen surface, which exhibits high stability and film persistency. DTT is preferentially adsorbs on the steel surface through S atoms, followed by the adsorption of IM through N atoms. The co-adsorbed film becomes denser due to hydrogen bonds and van der Waals interactions between IM and DTT molecule.