Search Results (856)

Benzimidazole derivatives are widely used as a drug. In this work, we valorized the electrochemical activities of our new Benzimidazole-derived compound, 2-(4-chlorophenyl)-4-nitro-1H-benzimidazole (OS1), as a green inhibitor that can be used in environmental applications, which gives rise to a tautomeric equilibrium (A and B), applied to mild steel in a 1 M HCl solution. The inhibitory effect of 2-(4-chlorophenyl)-4-nitro-1H-benzimidazole (OS1) on carbon steel (CS) corrosion in 1 M HCl was evaluated with DFT studies. The value ΔN = 0.019 for A and 0.057 is positive and less than 3.6, indicating that the molecule functions as an electron donor towards the iron substrate, creating a shielding layer that prevents corrosion. DFT results identified the nucleophilic that C(4,6,24) N(12) O(15) and Cl(27) in A and C(4,5,6,32) O(14,15) and Cl(26) in B and electrophilic C(6) N(12) and O(15) in A and O(14,15) in B attack sites. Notably, these findings established that Tautomer A is the most stable. Full article

The aqueous seed extract of Ammodaucus leucotrichus Cosson & Durieu (AL-AE), a Saharan annual herb of the family Apiaceae, was evaluated for the first time as a green corrosion inhibitor for mild steel in 1.0 M hydrochloric acid. GC-MS analysis after acetylation derivatization identified ten constituents representing 99.22% of the total detected area, with 17-pentatriacontene (47.69%), 2,4-di-tert-butylphenol (13.24%), and myo-inositol (8.62%) as the dominant species. Inhibition performance was assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) over 25–100 ppm at 298–328 K. At 100 ppm and 298 K, AL-AE achieved 96.17% by EIS and 97.10% by PDP. Adsorption obeyed the Langmuir model with a standard free energy of adsorption of −38.2 kJ mol⁻¹, consistent with a mixed physisorption–chemisorption mechanism. SEM/EDS confirmed protective film formation, with surface oxygen dropping from 34.9 to 4.1 wt%. Density functional theory (DFT) calculations at the B97-3c/CPCM (water) level in ORCA 6.1 identified 2,4-di-tert-butylphenol as the most reactive constituent, while Fukui index analysis based on Mulliken population analysis located the preferential adsorption sites on each molecule. Full article

Admiralty brass, commonly used in heat exchangers, is particularly susceptible to corrosion in acidic media such as those used in industrial cleaning. To mitigate this problem, the present study evaluated Musa acuminata (banana) peel and Lupinus mutabilis Sweet (Andean lupine) extracts as sustainable, low-toxicity corrosion inhibitors for admiralty brass in 0.5 M HCl. Six extracts were prepared using different solvents and characterized by qualitative and semi-quantitative phytochemical analyses (phenols, flavonoids, alkaloids). M. acuminata extracts were rich in phenolic compounds, while L. mutabilis extracts contained high levels of quinolizidine alkaloids. A comparative electrochemical screening of the agro-industrial waste-derived extracts revealed that the inhibition efficiency of M. acuminata extracts reached up to 43.6%, whereas the debittering wastewater extract of L. mutabilis (E6) achieved a maximum efficiency of 85.5% at 2000 ppm. A preliminary techno-economic analysis indicated the feasibility of industrial-scale production of the L. mutabilis-based inhibitor, yielding a net present value (NPV) of USD 9.48 million, an internal rate of return (IRR) of 27.3%, and a payback period of 6.7 years. These results demonstrate that agro-industrial residues can be valorized into effective and profitable green corrosion inhibitors, aligning with circular economy and sustainable chemistry principles. Full article

The use of environmentally friendly corrosion inhibitors in corrosive solutions has attracted considerable attention over the past few decades. However, the uncontrolled use of such inhibitors in aggressive environments can lead to a reduction in the long-term corrosion protection performance of the system. Moreover, the need for frequent re-dosing of the inhibitor increases the overall cost. One of the effective approaches for controlled and smart release of inhibitors in corrosive media is the use of nanocarriers, in which the inhibitor molecules are adsorbed onto the surface of nanoparticles and subsequently desorbed into the corrosive electrolyte through a specific release mechanism. Among the commonly used methods to obtain such eco-friendly inhibitors is the extraction of plant-based compounds, which are abundant and cost-effective. In this study, zinc oxide (ZnO) nanoparticles were green-synthesised using a plant extract and employed as nanocarriers for the controlled release of phytochemicals in 1 M HCl solution. The corrosion behaviour of carbon steel (St37) was investigated using electrochemical polarisation techniques. Results revealed that the system acts as a mixed-type inhibitor, achieving an inhibition efficiency of approximately 85% at optimal concentration, demonstrating its potential as a sustainable and cost-effective alternative for corrosion protection. Full article

Magnesium alloys offer low density, high strength, excellent heat dissipation, and good electrical conductivity, benefiting automotive and aerospace sectors. However, magnesium and its alloys are highly susceptible to corrosion, which severely limits their practical use. In this study, the hydrothermal deposition of graphene oxide (GO) and layered double hydroxides (LDHs) was achieved on the surface of an anodized magnesium alloy, forming a GO/LDH coating. The effects of pH and various anionic corrosion inhibitors on the corrosion resistance of the GO/LDH coating were subsequently investigated. The results show that the GO/LDH coating prepared at pH 10.8 exhibits the best corrosion resistance, which is generally associated with a greater coating thickness, with its nanosheets growing in a wavy manner in all directions. This coating also shows higher crystal transparency and a denser layered structure. Based on this, anionic corrosion inhibitors including molybdate, vanadate, and tungstate were incorporated into the GO/LDH coating. Electrochemical impedance (EIS) analysis subsequently revealed that the GO/LDH–molybdate coating exhibited the highest |Z|_{0.01 HZ}, reaching ~10^5.5 Ω cm², indicating its excellent corrosion resistance. This approach offers a novel and effective route to significantly improve the corrosion resistance of magnesium alloys via synergistic coating design. Full article

Carbon steel pickled with hydrochloric acid can suffer from considerable dissolution, greater acid consumption, and poor surface quality. This research assessed the effectiveness of a commercially available corrosion inhibitor for carbon steel pickled under industrially representative conditions (13.2 wt.% (weight percent) HCl (hydrochloric acid), 28 g·L⁻¹ dissolved iron, 80–85 °C, and brief periods of contact with pickling solution at 32, 56, and 113 s). Mass loss and inhibitor efficiency (IE) were determined through gravimetric analysis under dynamic pickling conditions using varying concentrations of inhibitor and duration of contact. The results indicate that the extent of mass loss decreases considerably with increasing inhibitor concentration. The optimal concentration was found to be 0.6 g·L⁻¹, giving an inhibitor efficiency greater than 90% under preliminary screening conditions and 70–79% under industrially relevant conditions, with further increases in inhibitor concentration providing little additional protection, suggesting nearly complete surface coverage. Observations of the surface showed better pickling uniformity and brilliance. The optimal inhibitor concentration resulted in reductions of 21% in inhibitor usage and over 27% in acid regeneration compared to a non-optimized inhibitor dosage. Full article

The corrosion behavior of copper and a Cu-Fe-P alloy in 3.5% NaCl solution was studied in this paper. This study focused on the influence of microalloying in the Cu-Fe-P alloy containing 0.003 wt% Fe and 0.014 wt% P on corrosion resistance in chloride media. Additionally, the effect of 2-mercapto-1-methylimidazole as an inhibitor was evaluated using electrochemical techniques, including potentiodynamic polarization, cyclic voltammetry, and electrochemical impedance spectroscopy. According to the potentiodynamic polarization results, 2-mercapto-1-methylimidazole can be classified as a mixed-type inhibitor. The inhibition efficiency also increases with increasing concentration. The results indicate that the Cu-Fe-P alloy has improved corrosion resistance compared to copper, and a higher inhibition efficiency of 2-mercapto-1-methylimidazole was observed for the Cu alloy. Full article

This study aims to investigate the performance and mechanism of N′-[(E)-phenylmethylidene] furan-2-carbohydrazide (FNH), a hydrazone Schiff base, as a corrosion inhibitor for carbon steel in 1.0 M HCl. The research was conducted by coupling electrochemical testing (Tafel analysis and Impedance spectroscopy) with surface characterization (SEM and AFM) and advanced computational tools, including quantum-chemical modeling and classical molecular dynamics (MD) simulations. Tafel analysis revealed that FNH acts as a mixed-type inhibitor, concurrently slowing iron oxidation and hydrogen reduction. Impedance data showed that the Faradaic resistance grew monotonically with FNH dosage, reaching 95% protection at 1 × 10⁻⁴ M. Fitting the results to the Langmuir model indicated a joint physical–chemical anchoring pathway, further confirmed by SEM/AFM inspection which disclosed a uniform organic deposit. Quantum-chemical modeling revealed that protonated species broaden the molecule’s capacity for bidirectional electron exchange, while MD simulations on the Fe (110) slab confirmed a flat-lying geometry that maximizes heteroatom–metal contact. The consistency between laboratory observables and atomic-scale predictions provides a detailed, mechanism-oriented picture of how this organic protective layer curtails acid corrosion. Full article

The expired drug Detralex (90% diosmin and 10% hesperidin), known as an effective corrosion inhibitor, was adsorbed onto mesoporous silica and incorporated into an epoxy matrix to enhance the coating’s corrosion protection in a highly corrosive 3 wt% NaCl solution. It was found that this treatment, by improving adhesion, modifying the hydrophilic properties, and enabling inhibitor release, increased the coating’s resistance over time. Based on an SEM-EDX analysis, even after 24 h of immersion, the epoxy coating with mesoporous nanosilica adsorbed with diosmin and hesperidin retained the incorporated inhibitors. This resulted in a slight increase in the samples’ polarization resistance during longer exposure. Full article

The article deals with the study of stress corrosion cracking (SCC) of X70 steel using corrosion-mechanical testing that simulates the operating conditions of underground pipelines. The tests were carried out under cyclic four-point bending at stresses close to the yield point, in electrolytes with various hydrogen charging capacities. The following model environments were used: NS4 solution and citrate buffer (pH 5.5). Hydrogen charging was controlled by the addition of thiourea and by varying the potential. It was shown that microcracks initiated at corrosion defects (pits) and then emerged at the surface to form narrow cracks. The incubation period depends on the environment: under corrosive conditions it is approximately two times shorter than in the air. The size and nature of stress concentrators play a significant role: natural pits (~hundreds of μm) lead to crack formation within 24–28 days, whereas artificial holes (0.6–1 mm) lead to crack formation within 5–7 days. The effect of hydrogen was established: the acceleration is insignificant under moderate hydrogen charging, whereas the incubation period decreases sharply at high hydrogen charging. Critical hydrogen concentrations where its effect becomes significant were determined. Methods for inhibiting stress corrosion cracking by means of organosilicon films (vinyl- and aminosilanes, as well as their mixtures with inhibitors—benzotriazole and amines) were considered. The most effective composition is vinylsilane + benzotriazole: the time to crack initiation increases from 5 to 36 days, and the crack growth rate decreases. Full article

Lubricants contain various types of additives, with corrosion and rust inhibitors being some of the most important. Due to the importance of 2,5-Dimercapto-1,3,4-thiadiazole (DMTD) in the field of corrosion inhibitors, we used it as a key intermediate to synthesize a series of 4-thiazolidinone and 4-imidazolidinone derivatives. This work also includes performing the reaction of DMTD with ethyl chloroacetate, which produced the corresponding ester, followed by the conversion into a hydrazide derivative using hydrazine hydrate. The next step is the condensing of the yielded hydrazide with various aromatic aldehydes yielding Schiff bases, which were subjected to cyclization by means of mercapto acetic acid and ethyl glycinate to produce the target 4-thiazolidinone and 4-imidazolidinone derivatives, respectively. FT IR, ¹H NMR, and ¹³C NMR spectroscopies were involved to confirm the structures of these derivatives. The synthesized derivatives have been evaluated as copper corrosion and rust inhibitors for medium lubricants in accordance with ASTM-D130 and ASTM-D665 standards. Interestingly, some lubricant blends of the synthesized derivatives showed good performance as copper corrosion and rust inhibitors. Full article

This study presents a theoretical investigation of the adsorption and electronic structure of two imidazole derivatives, 4-(1,4,5-triphenylimidazol-2-yl)-aniline (M1) and N,N-dimethyl-4-(1,4,5-triphenylimidazol-2-yl)-aniline (M2), on an Fe(100) surface. A combined computational approach, employing Density Functional Theory for molecular reactivity, Density-Functional Tight-Binding for surface interactions, and Molecular Dynamics (MD) simulations for binding stability, was utilized to provide a comprehensive analysis. Quantum–chemical calculations indicate that both inhibitors exhibit strong donor characteristics, with M2 consistently demonstrating greater potential. This enhanced performance is attributed to the strong electron-donating nature and increased structural planarity conferred by the dimethylamine group in M2, which results in a lower HOMO-LUMO energy gap and higher chemical reactivity. Analysis of the inhibitor-surface interaction confirmed a strong electron donor-acceptor mechanism, indicative of stable chemical bond formation and a predominant chemisorption process. MD simulations revealed that both molecules form stable adsorption layers on the iron surface, suggesting initial adsorption behavior. Full article

Corrosion of materials is a global issue affecting various industries. It leads to a gradual decline in the durability and reliability of materials, resulting in significant economic losses and posing serious risks to human health. To address the challenge of enhancing reliability and durability when materials are exposed to aggressive environments, this study developed new polymer protective coatings. These coatings involve reinforcing an epoxy resin-based polymer matrix with zinc and microencapsulated corrosion inhibitors (activated Al₂O₃ + HEDP; activated Al₂O₃ + PPA; activated Al₂O₃ + ATMP). These microscopic containers encapsulate the corrosion inhibitors. The microstructure of the microcapsules was examined using scanning electron microscopy (SEM) and optical microscopy. Accelerated corrosion tests were performed on the reinforced modified coatings. Coatings reinforced with activated Al₂O₃ + HEDP microcapsules demonstrated excellent corrosion resistance in a 3% NaCl solution. In contrast, samples coated with unmodified zinc-filled coatings and coatings modified with Al₂O₃ + PPA exhibited the lowest resistance in a 3% NaCl solution. The study also investigated the microdefect-blocking effect in reinforced coatings, which is achieved by filling the pores of the polymer coating with products formed from inhibitor–metal interactions. Full article

The corrosion of carbon steel in marine–industrial atmospheric environments remains a significant challenge due to the combined effect of aggressive ions such as chlorides and sulfates. In this context, this study aims to explore the inhibitory action of expired omeprazole applied to mild steel AISI 1018 evaluated on a solution simulating atmospheric corrosion (0.1 M Na₂SO₄ + 3% wt NaCl) over 72 h. The material was characterized using EDS to determine its composition of AISI 1018 steel, while Raman spectroscopy was employed to identify the functional groups and heteroatoms present on the molecular structure of omeprazole. Electrochemical noise (EN) measurements were used to evaluate the corrosion rate, type of corrosion and mechanism. Also, quantum chemical calculations of density function theory (DFT) were performed to predict the relationship between molecular structure and inhibition efficiency. The results indicate that 50 ppm provides the most stable and effective corrosion inhibition over time, as evidenced by increases in noise resistance and inhibition efficiency. In contrast, 75 ppm exhibits improved surface morphology at the end of the exposure period, which indicates enhanced surface coverage. The DFT results reveal that omeprazole possesses suitable electronic properties for corrosion inhibition, including moderate reactivity, electron-donating ability, and favorable charge distribution that promotes adsorption onto the metal surface. SEM analysis corroborates that surface damage is significantly reduced in the presence of the inhibitor, particularly at 75 ppm. This study provides new insights into the use of expired pharmaceutical compounds as corrosion inhibitors and demonstrates the capability of combining electrochemical noise analysis with DFT to evaluate both inhibition efficiency and film stability. Full article

In this work, welan gum (WG) was investigated as a green corrosion inhibitor for metals in acidic petroleum drilling fluids. The side chain of WG was subsequently modified by grafting with 3-chloropropionic acid (WG-CAR), further improving the corrosion inhibition performance. At the same concentration, WG exhibited a better corrosion inhibition efficiency than the commercial β-cyclodextrin. Moreover, the graft-modified WG-CAR achieved 60.35% at a concentration as low as 100 ppm, whereas WG and β-cyclodextrin only reached 28.25% and 25.42%, respectively. These improvements are attributed to their electron-donating hydroxyl and carboxyl functional groups, through which the lone pair electrons in oxygen atoms can fill the unoccupied d-orbitals of iron atoms, forming coordination bonds. This promotes Langmuir chemisorption, thereby forming a protective layer on the steel surface that inhibits anodic and cathodic corrosion reactions. In addition, calculations show that the WG-CAR molecule possesses a larger dipole moment and enhanced electron-donating capacity, resulting in stronger coordination interactions for the protective layer. Even at a high temperature of 323 K, WG-CAR (200 ppm) maintains an inhibition performance of 36.80%, higher than that of WG (10.66%). This work broadens the application of WG and brings new perspectives for the development and design of corrosion inhibitors. Full article