Corrosion Inhibition Of Steel Research Articles

Electrochemical analysis of corrosion inhibition shallot leaf (Allium cepa) extract on mild steel in acidic medium at different immersion times

Plant derivatives as eco-friendly corrosion inhibitors are currently greatly interested in much research. Shallot leaf (Allium cepa) was utilized in 0.1M HCl as a corrosion inhibitor of mild steel. The functional groups present in the macerated extract were subsequently identified using an FTIR test. Electrochemical tests such as tafel polarization and EIS were carried out to determine the corrosion inhibition performance of shallot leaf extract on the SS400 steel. The results of the electrochemical analysis show that shallot leaf extract can inhibit mild steel up to 94% at a concentration of 500 ppm. Furthermore, the addition of SLE reduces surface damage of mild steel, which can be seen by SEM.

Corrosion inhibition of carbon steel by eucalyptus leaves in acidic media: An overview

This paper concerns the overview of previous studies on the corrosion and inhibition of carbon steel that is allowed to degrade in a corrosive medium by the extract of the eucalyptus plant, with an emphasis on the extract's adsorption behaviour. Many researchers have largely employed eucalyptus plant bark, oil, and leaf extracts to prevent the corrosion of mild steel in acidic environments under various temperature settings. According to the results, when the bark extract of the eucalyptus plant was added to HCl (5%) at a concentration of 900 ppm, the inhibitor's maximum efficiency was 98.2 %. The leaf extract, on the other hand, had the maximum inhibitory efficacy of 93.09 % at 600 mg/L extract concentration in the H2SO4 (0.5 M) medium. The extracts' potency was shown to diminish with increasing temperature. The mechanism for eucalyptus extract's protection of carbon steel from corrosion in diverse corrosive situations was largely associated with the adsorption of the extract's inhibitive components on the steel's surface to reduce the interaction between the metal and the corrosive surroundings. The majority of the reported inhibitive behaviour of the eucalyptus extract was consistent with the Langmuir adsorption isotherm model.

ρ-Substituted imine cationic surfactants as carbon steel corrosion inhibitors: Experimental and theoretical (DFT and MCs) approaches

In this study, we synthesized cationic surfactants based on ρ-substituted Schiff base compounds—S-12 (E)-N-dodecyl-N,N-dimethyl1-4-((P-olylimino)methy)benzene aminiumchloride) and SO-12 (E)-N-dodecyl-4-(((4-methoxyphenyl)imino)methyl)-N,N-dimethyl benzeneaminiumchloride. Their chemical structures were confirmed via FTIR and 1HNMR spectroscopies. SO-12 decreased the surface tension of 1 M HCl (61 mN.m−1) to 24.4 mN.m−1. Weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements were employed to investigate carbon steel (CS) corrosion reactions in blank HCl and HCl containing the synthesized surfactants. The CS corrosion suppression actions of S-12 and SO-12 increased with increasing concentrations until they reached approximately 97 %. Adsorption of S-12 and SO-12 delayed the CS corrosion rate. The adsorption process fitted the Langmuir adsorption isotherm. The thermodynamic properties of the CS reaction are also discussed. The surface morphology and elemental analysis of the outer surface layer of CS were studied at the optimal concentration of SO-12 using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Theoretical results of S-12 and SO-12 agree with experimental data, confirming the effectiveness of S-12 and SO-12 as corrosion inhibitors. Moreover, S-12 and SO-12 have superior performance compared with previously reported cationic surfactants under the same test conditions.

Exploration of aspartame as a green and sustainable corrosion inhibitor for T95 steel in 28 wt.% HCl at elevated temperatures: effect of sodium dodecylsufate and KI addition on performance

Acidizing is a vital oil well stimulation exercise but must be done with an effective corrosion inhibitor to reduce corrosion risk. It is, however becoming increasingly difficult to find a corrosion inhibitor that is ecologically compatible and effective in strong acids and high temperatures. In this scientific communication, aspartame (ASP), sodium dodecylsufate (SDS), and potassium iodide (KI) blend is presented as a highly efficient inhibitor for T95 steel in 28 wt.% HCl solution at 60–90 °C. The corrosion inhibition investigation was performed using weight loss and electrochemical (electrochemical impedance spectroscopy [EIS] and potentiodynamic polarization [PDP]) techniques complemented by surface analysis of the corroded steel without and with the inhibitor using scanning electron microscope (SEM)/energy dispersive x-ray spectrophotometer (EDX), and 3D optical profilometry (OP). ASP is an effective corrosion inhibitor for T95 steel in an acidizing environment. The inhibition efficiency (IE) increased with an increase in concentration and temperature. The additives (SDS and KI) enhanced the inhibitive performance of ASP due to synergistic effects, especially at 90 °C where an IE of 96% is tenable. Results from SEM/EDS and OP disclose apparent ASP-based inhibitor adsorption on the T95 surface and a high level of protection.

Experimental Study on Adsorption and Corrosion Inhibition Properties of <i>Urena lobata</i> Leaves Extract on Mild Steel in Acidic Medium

The corrosion inhibitive effect of <i>Urena lobata</i> leaves extract on mild steel in 1M HCl solution was investigated via gravimetric, Electrochemical and Surface analyses. Adsorption isotherms were investigated using the Langmuir and Freundlich plots. Phytochemicals of the extract were investigated using Gas Chromatography-Mass Spectrometric (GC-MS) technique. The effect of the leaves extract through immersion time, temperature and concentration on the corrosion inhibition were obtained. The results obtained showed that the increase in extract’s concentration increased the inhibition efficiency and the protection was more on the surface of the metal at lower temperature. Maximum inhibition efficiency of 95.8% was obtained at 2.5g/L extract concentration. Corrosion rate of mild steel increased with temperature increase in the acidic solution. The adsorption process reduced as temperature increased thereby indicating physisorption. The Langmuir isotherms gave the best fit indicating chemisorption. Physical adsorption was confirmed for the leaves extract from observations of inhibition efficiency with temperature, activation energy and enthalpy of adsorption values. Hence indicating that the plant extract has mixed properties. The electrochemical results confirmed the inhibitory ability of the plant extract. The inhibition efficiencies (% IE) were attributed to the phytochemical components (alkaloids, saponins, flavonoids, tannins, cynagenic glycosides) present in the extract. The extracts of <i>Urena lobata</i> are effective corrosion inhibitors of mild steel.

Electrochemical, gravimetric, quantum chemical and computational investigations on an effective synthetic chlorinated cyclic imide derivative as a corrosion inhibitor for carbon steel in sulfuric acid solution

Although many different human activities such as the oil and gas sector, mineral production, utilities, transportation, etc. depend on the utilization of steel and its alloys, they are highly susceptible to corrosion, especially in acidic media. Hence, processing entails substantial material expenditures due to metal losses. In this regard, the inhibitory characteristics of the synthetic heterocyclic derivative (3aR,7S,7aS)-4,5,6,7,8,8-hexachloro-1,3-dioxo-1,3,3a,4,7,7a-hexahydro-2H-4,7-methanoisoindol-2-yl)benzenesulfonamide (MBSI) was studied against corrosion of C-steel in 0.5 M H2SO4 at 25-55 °C. The structure of the synthesized molecule was confirmed by FTIR, 1H-NMR, 13C-NMR, and MS. Weight-loss, potentiodynamic polarization, electrochemical impedance spectroscopy, electrochemical frequency modulation measurements as well as theoretical analyses were employed in this investigation. The results showed that the investigated MBSI compound functions as an efficient inhibitor with a physical adsorption nature on the surface of carbon steel. MBSI concentration causes the inhibition efficiency to rise, reaching a maximum of 94% for the steel alloy corrosion at 37 × 10−6 M and 25°C. The synthesized compound was suggested to act as a mixed-type inhibitor. SEM surface analysis showed the construction of a protective layer at the carbon steel surface. DFT-based quantum chemical indices provided more insight into the inhibitory mechanism. Molecular dynamics (MD) simulations were also applied to predict the conformational adsorption change of the inhibitor on the iron surface. In addition, thermodynamic and kinetic parameters were calculated. The experimental results are largely consistent with the theoretical results.

Self-formation of the protective film on mild steel surface in hydrochloric acid medium containing Papaya resin extract

Plant extracts have been considered to be an effective corrosion inhibitor due to their high inhibition performance, huge amount, regeneration, and nature, as well as biological sources. However, several steps in the plant extract processes and extracted solvents are still questionable. Therefore, Papaya resin - extract (PRE) was recommended, produced, and characterized as a mixed-type inhibitor for corrosion of mild steel in 0.1 M hydrochloric acid medium. The results indicated that the 2000 ppm of PRE inhibitor has significant effects on the inhibition efficiency, reaching a remarkable value of 98.08% for mild steel in the investigated solution. The potentiodynamic polarization results showed that the PRE inhibitor acts as a mixed-type inhibitor with a dominant anodic inhibitor for mild steel. Moreover, electrochemical impedance spectroscopy and linear polarization resistance results demonstrated that PRE molecules can form protective film, and increase charge transfer and polarization resistances, suggesting the improved steel corrosion resistances. The scanning electron microscope results indicated less occurrence of corrosion on the steel surface exposed to the inhibitor system. Meanwhile, X-ray photoelectron spectroscopy results demonstrated that PRE’s molecules were absorbed and created reactions with iron products to form a protective film on the steel surface. Furthermore, density functional theory (DFT) and molecular dynamics simulation were used to calculate, suggesting that the conjugation effect of two double bonds in PRE’s molecules creates an electron-withdrawing effect on the reactive space around. Moreover, the results revealed the good adhesion and thermal stability of the absorbent protective layer, indicating an agreement with experimental characteristics. Therefore, this result suggests a contemporary design for developing the self-corrosion inhibitor based on natural products with less steps in the synthetic process.

Justicia brandegeeana as a green corrosion inhibitor for carbon steel in sulfuric acid

ABSTRACT The anti-corrosive effect of the extract in ethanol of Justicia brandegeeana (Acanthaceae) against carbon steel AISI 1020 in sulfuric acid medium 1 mol L−1 was investigated. In addition to the effect of seasonality, several techniques were used to investigate the anti-corrosive activity, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP), linear polarization resistance (LPR), and weight loss. The chelating effect was analyzed by UV-Vis spectrophotometry and the surface was analyzed by scanning electron microscopy (SEM). The results showed that the inhibition efficiency is dependent on the concentration of the extract, reaching its maximum at 1500 ppm and despite having good thermal stability (82.41% inhibition at 70°C), it decreases with increasing temperature, indicating a physisorption behavior. The extract obeyed the Langmuir isotherm and the Tafel curves characterized it as a mixed inhibitor, with a tendency to cathodic region. It also presented a 52% chelating effect against Fe+2 ions, and the SEM analysis indicated a protection with the presence of plant extract, thus minimizing surface roughness. These results indicated the J. brangeeana ethanol extract as a green anti-corrosive agent.

Green Ostrich fat waste extracts as a novel potential inhibitor to sustainable corrosion of steel in acidic environments: Electrochemical and DFT evaluation

The shift from traditional chemical corrosion inhibitors to green alternatives, focusing on plant extracts (GCIs), addresses environmental concerns in line with sustainable development goals. An innovative approach explores animal-derived extracts for eco-friendly corrosion inhibition, addressing environmental issues associated with conventional chemical inhibitors. Ostrich Oil, renowned for its nutritional, cosmetic, and pharmaceutical properties, is examined as a potential green corrosion inhibitor for C38 steel in 1 M hydrochloric. Extracted and characterized through GC-FID, Ostrich Oil exhibits corrosion protection analyzed via impedance spectroscopy, potentiodynamic polarization, and gravimetric methods. Complementary SEM and metallurgical microscopy with EDS offer surface insights. DFT and MD simulations explore the relationship between electronic properties and inhibition efficiency. Results show Ostrich Oil's significant corrosion inhibition (up to 94%), attributed to chemical adsorption of fatty compounds. The corrosion mechanism is influenced by Oil extract adsorption, increasing double electrochemical layer resistance. Gas chromatography identifies main compounds, and quantum chemical calculations highlight its reactivity. This research underscores the potential of animal-derived extracts, exemplified by Ostrich Oil, as effective and environmentally friendly corrosion inhibitors, contributing to sustainable corrosion protection practices.

Effect of tabebuia heterophylla plant leaves extract on corrosion protection of low carbon steel in 1M HCl medium: Electrochemical, quantum chemical and surface characterization studies.

In the current study the chemical constituents of Tabebuia heterophylla plant leaves extract (THLE) evaluated as corrosion inhibitor for low carbon steel (LCS) in 1 M HCl. The major component present in plant extract was Hexadecanoic acid 2-hydroxy-1-(hydroxymethyl) ethyl ester confirmed by Gas Chromatography with Mass spectroscopic (GC-MS) analysis. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarisation (PDP) and weight loss measurements were used to evaluate the THLE ability to protect low-carbon steel surface against corrosion in 1M HCl medium. The maximum inhibition efficiency reported as 95.45%, 93.99% and 94.79% by weight loss measurements, EIS and PDP methods respectively. In the prolongation of the work, the entropy of adsorption (Δ Sa*), enthalpy of adsorption (Δ Ha*), Gibbs free energy of adsorption (Δ Ga*), and activation energy (Ea) of the reaction were calculated. In absence of inhibitor, the Ea value was found to be minimum 49.38 kJ/mol whereas for optimum concentration of THLE it was found to be 77.2 kJ/mol implies more energy is required to undergo corrosion. The surface morphological observation from Scanning Electron Microscope (SEM), Atomic Force Microscopic (AFM) and Contact angle explored the effective adsorption of THLE. AFM values revealed that average surface roughness (Ra) value of LCS is high (188.08), where as in the presence of THLE, Ra values significantly reduced to minimum value of 37.226. Further chemical interactions between THLE and the low-carbon steel surface as well as inhibitory mechanism were further elucidated by theoretical simulations such as Density Functional Theory (DFT) calculations and Molecular dynamics (MD) simulations.

Adsorption and Inhibition Mechanisms of New Pyrazole Derivatives for Carbon Steel Corrosion in Hydrochloric Acid Solutions Based on Experimental, Computational, and Theoretical Calculations.

The study aims to synthesize two green pyrazole compounds, N-((1H-pyrazol-1-yl)methyl)-4-nitroaniline (L4) and ethyl 5-methyl-1-(((4-nitrophenyl)amino)methyl)-1H-pyrazole-3-carboxylate (L6), and test their action as corrosion inhibitors for carbon steel (CS) in a 1 M HCl solution. Both chemical and electrochemical methods, namely, gravimetric measurements (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS), were used to assess the efficiency of the investigated molecules. DFT calculations at B3LYP/6-31++G (d, p) and molecular dynamics simulation were used to carry out quantum chemical calculations in order to link their electronic characteristics with the findings of experiments. The organic products exhibited good anticorrosion ability, with maximum inhibition efficiencies (IE %) of 91.8 and 90.8% for 10-3 M L6 and L4, respectively. In accordance with PDP outcomes, L6 and L4 inhibitors act as mixed-type inhibitors. Assessment of the temperature influence evinces that both L4 and L6 are chemisorbed on CS. The adsorption of L4 and L6 on CS appears to follow the Langmuir isotherm. Scanning electron microscopy and UV-visible disclose the constitution of a barrier layer, limiting the accessibility of corrosive species to the CS surface. Theoretical studies were performed to support the results derived from experimental techniques (WL, PDP, and EIS).

Electrochemical studies, adsorption behavior, and spectroscopic analysis of vanadyl complex of bis(1-(pyridin-2-yl)ethylidene)malonohydrazide as efficient eco-friendly corrosion inhibitor for low carbon steel in 1M HCl

Corrosion is a destructive attack that can effect on a substance. One of the most important problems is corrosion losses, which can cause a loss of 10% of the metallic output every year. A novel VO+2 complex of N1, N3-bis(1-(pyridin-2-yl)ethylidene)malonohydrazide [(VO)2(L)(OH)2].H2O has been prepared and utilized as corrosion controller for Low carbon steel (LCS) in hydrochloric acid solution. Chemical (Weight loss (WL)), electrochemical (electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP)) are utilized to examine the effectiveness of prepared [(VO)2(L)(OH)2].H2O (VOL). The inhibition efficacy improved with increasing the VOL doses. The maximum efficacy of the investigated inhibitor is 96.1% at 21×10−6 M. However, at 21×10−6 M, the efficacy decreased from 96.1% to 84.4% when the temperature elevated from 298 to 318 K. The adsorption of VOL on the LCS surface was used to explain the inhibition. According to the values of ∆G°ads, which ranged from 25.8 to 21.5 kJ mol−1, the adsorption of the VOL on the LCS surface is physical adsorption. Analyzing the polarization curves of synthesized inhibitors revealed that they were mixed-type inhibitors. LCS was found to be surface inhibited when coated with a thin film of inhibitors, and surface morphology was assessed by different techniques such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) was employed to explain the nature of the interface among VOL and LCS surfaces. It was found that all of these used tests agreed with each other.

Oleaster Leaf Extract: A Potential Environmentally Friendly Inhibitor for Mild Steel

In this research, the potential of Elaeagnus angustifolia tree leaf extract as a green corrosion inhibitor for mild steel in hydrochloric acid solution was examined. The stock concentration of the aqueous extract was determined to be 0.38% (w/v). Other experimental solutions were created by diluting four different extract concentrations in aggressive solution. Experimental measurements, including linear polarization (LPR), electrochemical impedance spectroscopy (EIS), and semi-logarithmic current potential curves by Tafel extrapolation method, were employed to validate the corrosion inhibition effects of the plant leaf extract at varying concentrations. Notably, oleaster leaf extract demonstrated a corrosion protection of over 80% for mild steel, even at low concentrations, attributed to its abundance in secondary metabolites such as polyphenols and flavonoids. The atomic force microscopy (AFM) surface maps provide robust evidence for the electrochemical measurement data.

Unveiling the potent corrosion-inhibiting power of Ammophila arenaria aqueous extract for mild steel in acidic environments: An integrated experimental and computational study

Plant extracts have emerged as potent inhibiting compounds for metallic corrosion, offering numerous advantages including simple accessibility, low toxicity, eco-friendliness, biocompatibility, effectiveness, and renewability. In this study, the potential of Ammophila arenaria extract as a green corrosion inhibitor for mild steel in 1.0 M HCl over the concentration range of 25–700 ppm was evaluated, using various electrochemical analyses such as Open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Results revealed a notable reduction in the corrosion rate of steel, particularly at 700 ppm, where Ammophila arenaria extract demonstrated its highest inhibition efficiency, reaching 83.67% for polarization and 84.32% for EIS. The cathodic and anodic polarization curves indicated that the aqueous extract of Ammophila arenaria functions as a mixed-type inhibitor. The thermodynamic analysis revealed a negative Gibbs free energy value (∆Gads°), suggesting spontaneous physisorption as the predominant adsorption mechanism. To delve into the inhibition mechanism at the molecular level, the surface morphology of mild steel exposed to 1.0 M HCl solutions, both in the absence and presence of Ammophila arenaria aqueous extract, was scrutinized through Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Theoretical techniques, including Quantum Calculation Theory, Non-Covalent Interaction (NCI), and Atom In Molecule (QTAIM), were concurrently employed, providing valuable insights into molecular-level interactions. Remarkably, the computational studies complemented and corroborated the experimental data. These comprehensive results significantly contribute to the understanding of Ammophila arenaria extract's corrosion inhibiting properties, endorsing its potential as a sustainable and environmentally friendly corrosion inhibitor suitable for diverse industrial applications. The synergistic integration of experimental and computational approaches establishes a robust foundation for future endeavors in the field of green corrosion inhibitors.

An Eco-friendly Mangifera indica Leaves Extract Corrosion Inhibitor for Stainless Steel in Acidic Medium

Corrosion of metals and alloys is one of the most frequent problems encountered in chemical and process industries. Inefficient corrosion control measures typically lead to an increased risk of unplanned downtime, huge economic loss, environmental damage, and health and safety hazards. Hence, it is essential to develop environment-friendly and cost-effective corrosion inhibitors over existing toxic anticorrosive agents. The main objective of this work is to examine the efficacy of eco-friendly ethanolic extract of Mangifera indica leaves (MIL) in different concentrations as a green corrosion inhibitor for stainless steel (SS-316L) under an acidic environment. The inhibition efficiency of Mangifera indica leaves extract in 1 M hydrochloric acid (HCl) was evaluated by conventional weight loss method along with adsorption isotherm analysis. Chemical compounds present in leaf extract and changes in surface morphology of SS-316L samples were assessed using Fourier Transform Infrared spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FE-SEM) provided with elemental analysis. The results of the weight loss method revealed that the inhibition efficiency increases with increasing MIL extract concentration due to higher surface coverage. The highest inhibition efficiency of almost 63.43% in 14 days and minimum corrosion rate of 0.433 mm per year was obtained for SS-316 L in 1.0 M HCl with 1000 ppm concentration. The adsorption of MIL extract on SS-316L surface followed Freundlich adsorption isotherm, and the obtained value of free Energy of adsorption (ΔG˚ads = – 9.20 kJ.mol-1) indicates the physical adsorption mechanism. The developed regression-based models can predict the corrosion rate as a function of inhibitor concentration and exposure time with good accuracy (>80%). Thus, the present findings demonstrate that Mangifera indica L. leaves extract can suitably be applied as an inexpensive, non-toxic, biodegradable, efficient green corrosion inhibitor for the protection of stainless steel in acidic media.

Excellent performance of amoxicillin and potassium iodide as hybrid corrosion inhibitor for mild steel in HCl environment: Adsorption characteristics and mechanism insight

Combining inhibitors is a key strategy to increase inhibitory efficacy because of synergistic effects. In this study, a green pharmaceutical inhibitor, amoxicillin (AML), was screened and compounded with potassium iodide (KI) to successfully obtain a synergistic and highly efficient green inhibitor. The results revealed that AML/KI have excellent anticorrosion ability for Q235 steel in 1 M HCl medium. At the optimal concentration ratio of 2 mM AML +5 mM KI, the inhibition efficiency was up to 97.7%, which was significantly higher than that of AML alone (57.4%). The hybrid inhibitor remarkably hinders the corrosion process by inhibiting both the cathodic and anodic reactions. Scanning electron microscopy, electron dispersive spectroscopy, contact angle measurement, ultraviolet–visible spectrometry and X-ray photoelectron spectroscopy, as well as Fourier transform infrared spectroscopy, results further confirm the outstanding inhibitory effect and the formation of synergistic adsorption films. Through density functional theory (DFT) calculations, we discovered that the KI salt significantly enhances the adsorption characteristics of AML/KI on the Fe surface, which is consistent with the experimental findings. This research paves the way for a new breed of green hybrid corrosion inhibitors to be created.

New Inhibitor Based on Hydrolyzed Keratin Peptides for Stainless Steel Corrosion in Physiological Serum: An Electrochemical and Thermodynamic Study.

Reducing the impact of some biological fluids on bioimplants involves the control of surface characteristics by modeling the interface architecture and assembling ecofriendly thin films to retard corrosion. Therefore, a mixture of hydrolyzed keratin peptides (HKER) was investigated as a corrosion inhibitor for 304L stainless steel (SS) in physiological serum (PS), using electrochemical measurements associated with optical microscopy and atomic force microscopy (AFM). The tests, performed for various concentrations of the inhibitor at different temperatures, showed that the inhibition efficiency (IE) decreased with a rise in temperature and proportionally increased with the HKER concentration, reaching its maximum level, around 88%, at 25 °C, with a concentration of 40 g L-1 HKER in physiological serum. The experimental data best fitted the El-Awady adsorption model. The activation parameters (Ea, ∆Ha and ∆Sa) and the adsorption ones (∆Gads0, ∆Hads, ∆Sads) have highlighted a mixed action mechanism of HKER, revealing that physisorption prevails over chemisorption. AFM parameters, such as the average roughness (Ra), root-mean-square roughness (Rq) and maximum peak-to-valley height (Rp-v), confirmed HKER adsorption, indicating that a smoother surface of the 304L stainless steel was obtained when immersed in a PS-containing inhibitor, compared to the surface designed in blank solution, due to the development of a protective layer on the alloy surface.

Corrosion inhibition of mild steel in acidic environments: Mechanistic insights and protective effects of azo-cum inhibitor

An examination was conducted on a newly developed compound named N1-(coumarin-7-yl) amidrazone (Azo-Cum) to assess its impact on the corrosion of mild steel (MS) in a 1 M hydrochloric acid (HCl) solution. Various analytical techniques, including weight loss, potentiodynamic polarization (PDP), impedance spectroscopy (EIS), cyclic voltammetry (CV), UV–visible spectroscopy, scanning electron microscopy (SEM), and AFM, were employed to evaluate the inhibitory efficiency of the compound. The findings indicated that inhibition efficiency rose with higher concentrations but decreased with elevated temperatures. According to weight loss analysis, the optimal concentration of the new eco-friendly inhibitor (5 ×10−4 M) exhibited a maximum efficiency of 89.26%. Polarization studies disclosed that Azo-Cum acted as a mixed-type inhibitor with a cathodic predominance. The adsorption of the inhibitor on the MS surface followed the Langmuir adsorption isotherm. Additionally, the study explored the synergistic effect of Azo-Cum in combination with KI on MS corrosion in a 1 M HCl (Blank) solution using potentiodynamic polarization measurements. The results identified concentration ranges that demonstrated antagonistic inhibition. Density functional theory (DFT) and molecular dynamic simulation (MD) calculations were performed to investigate the correlation between molecular and chemical reactivity.

Determination of the ability of migrating steel corrosion inhibitors to passivate corroding reinforcement in reinforced concrete structures

Introduction. The corrosion condition of steel reinforcement in reinforced concrete structures and products is the main factor determining their bearing capacity and durability. The alkalinity of the pore liquid of concrete (at pH > 11.8) in reinforced concrete structures and products under normal conditions ensures the passive state of steel reinforcement. In the presence or when chloride, sulfate and other analogous ions enter the concrete, the steel reinforcement of reinforced concrete structures and products depassives, despite the pH value > 11.8, and begins to corrode. In addition, depassivation and subsequent corrosion of steel reinforcement occur during carbonation (neutralization) of the protective layer of concrete due to a decrease in pH < 11.8. One of the promising options for slowing down or stopping the corrosion processes of steel reinforcement is currently the use of migrating corrosion inhibitors.
 
 The aim of the work was to obtain experimental data on the ability of migrating steel corrosion inhibitors to inhibit or completely stop the corrosion of reinforcement in reinforced concrete structures and products initiated by the presence of chloride ions (Cl-) in concrete or neutralization of the protective layer of concrete in relation to steel reinforcement.
 
 Materials and methods. The following types of migrating steel corrosion inhibitors were used for testing:
 
 – Cortec MCI-2020 (manufacturer – KORTEK RUS (KORTEK) LLC, suppliers – Ettrilat LLC, MONUMENT LLC);
 
 – IFKHAN-80 (manufacturer and supplier – IFKHAN LLC);
 
 – Basf Master-Protect 8000 CI (former name Protectosil ® CIT. Suppliers – MBS Construction Systems LLC, MPKM LLC, LKM-FLEET LLC).
 
 The determination of the ability of migrating steel corrosion inhibitors to inhibit or completely stop the corrosion of reinforcement was carried out by accelerated electrochemical research methods in accordance with State Standard 31383-2008 "Protection of concrete and reinforced concrete structures from corrosion. Test methods".
 
 Results. All three types of migrating steel corrosion inhibitors inhibit corrosion of steel reinforcement initiated by the presence of chloride ions in concrete by the age of 90 days. All three types of migrating steel corrosion inhibitors by the age of 30 days do not inhibit the corrosion of steel reinforcement initiated by concrete carbonation.
 
 Conclusions. According to the results of the work, it was revealed that the migrating steel corrosion inhibitors inhibit the corrosion of steel reinforcement initiated by the presence of chloride ions in concrete, while the corrosion initiated by the carbonation of concrete is not slowed down or stopped by migrating steel corrosion inhibitors.

Mechanistic insights into the corrosion inhibition of mild steel by eco-benign Asphodelus Tenuifolius aerial extract in acidic environment: Electrochemical and computational analysis

This study explores the novel application of Asphodelus Tenuifolius aerial extract (ATAE) as a corrosion inhibitor for mild steel in a 0.5 M HCl acidic environment. By utilizing techniques such as electrochemical measurements, gravimetric analysis, SEM, and CA assessments, the inhibitory potential of ATAE has been comprehensively evaluated. The results revealed a concentration-dependent enhancement in corrosion resistance, classifying ATAE as a mixed-type inhibitor by measuring the anodic (βa) and cathodic (βc) polarization slope values of 108.89 and −129.33 mV/dec. The peak inhibition efficiency was observed at 250 ppm, reaching an impressive IE% of 94.40 % at 298 K (Kelvin). The electrochemical analysis demonstrated a significant increase in charge transfer resistance (Rct) and polarization resistance (Rp) values, coupled with a decrease in Constant Phase Element (CPE.Yo) value to 162.94 μF, indicating heightened corrosion inhibition potential. Additionally, Theoretical calculations emphasized a strong interaction between ATAE and mild steel surface, characterized by a low energy gap (ΔE), indicating excellent anti-corrosion abilities at the micro-level. This study positions ATAE as a promising corrosion inhibitor, offering insights for further research in corrosion prevention strategies using a sustainable corrosion inhibitor.