Inhibitive action of ethanol extracts from Nauclea latifolia on the corrosion of mild steel in H2SO4 solutions and their adsorption characteristics

The inhibitive action of ethanol extracts from leaves (LV), bark (BK) and roots (RT) of Nauclea latifolia on mild steel corrosion in H₂SO₄ solutions at 30–60 °C was studied using weight loss and gasometric techniques. The extracts were found to inhibit the corrosion of mild steel in H₂SO₄ solutions and the inhibition efficiencies of the extracts follow the trend: RT > LV > BK. The inhibition efficiency increased with the extracts concentration but decreased with temperature rise. Physical adsorption of the phytochemical components of the plant on the metal surface is proposed as the mechanism of inhibition. The adsorption characteristics of the inhibitor were approximated by the thermodynamic-kinetic model of El-Awady et al.     

Interactions and corrosion mitigation prospective of pyrazole derivative on mild steel in HCl environment

The effectiveness of 1H?pyrazole?3,5?dicarboxylic acid 5?benzyl ester 3?phenyl ester (PCBPE) as a preventer for deterioration of IS 513 Gr. D steel in 1 M HCl medium is evaluated via weight loss, electrochemical impedance, and polarization techniques. Kinetic and thermodynamic parameters assessed the feasibility of the adsorption process at diverse temperatures. The inhibition action on mild steel has been enhanced with increasing PCBPE concentration. It is found from the polarization studies that PCBPE behaves as mixed type inhibitor in HCl medium. The adsorption process of PCBPE on mild steel surface from acid environment is favoured Langmuir adsorption isotherm. The shielding efficiency of PCBPE has been enhanced at elevated concentrations, and it has been diminished at amplified temperatures. The Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrum (EDS) were used to establish a surface characterization of metal specimens. A quantum chemical analysis of electron density distributions in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) demonstrated how the inhibitor undergoes adsorption on mild steel in 1 M HCl. All experimental findings substantiate the corrosion mitigation performance of PCBPE on mild steel in acidic environments.     

Utilization of biowaste as an eco-friendly biodegradable corrosion inhibitor for mild steel in 1 mol/L HCl solution

This report focuses on the application of a biodegradable biowaste [human hair-(HHR)], to produce a mild steel corrosion inhibitor. The performance of HHR extract in inhibiting metallic corrosion in 1 mol/L HCl was investigated. The analysis of the metal corrosion behavior using electrochemical and weight loss techniques revealed that HHR exhibits an efficient corrosion-mitigating effect via adsorption on the metal surface following a Langmuir isotherm. Tafel-plot results revealed the mixed-mode corrosion protection behavior of HHR. Surface analysis using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and Fourier transform infrared (FT-IR) spectroscopy provided evidence for the precipitation of a protective HHR film on the metal surface.     

Adsorption and inhibitive properties of aminobiphenyl and its Schiff base on mild steel corrosion in 0.5 M HCl medium

Electrochemical measurements were performed to investigate the effectiveness and adsorption behaviour of aminobiphenyl (Aph) and 2-(3-hydroxybenzylideneamino)biphenyl (Aph-S), as corrosion inhibitors for mild steel (MS) in 0.5 M HCl solution. Potentiodynamic polarization, linear polarization resistance (LP) and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behaviour in the absence and presence of different concentrations of Aph and Aph-S. In order to gain more information about adsorption mechanism the AC impedance technique was used to evaluate the potential of zero charge (PZC) from polarization resistance (R_p) versus voltage (E) plot. Potentiodynamic polarization measurements showed that Aph act as cathodic type inhibitor where as Aph-S act mixed type. The inhibition efficiency (IE%) increases with increasing concentration of compounds and reached 92.6% for Aph and 97.2% for Aph-S at 5 × 10⁻³ M. Double layer capacitance (C_dl) and polarization resistance (R_p) values are derived from Nyquist plots obtained from AC impedance studies. The experimental data fit Langmuir isotherm for both Aph and Aph-S, and from the adsorption isotherm some thermodynamic data for the adsorption processes are calculated and discussed. The effect of exposure time on the corrosion behaviour of mild steel in the absence and presence of inhibitor over 168 h was also studied.     

Investigation on corrosion inhibition and adsorption mechanism of azomethine derivatives at mild steel/0.5 ​M ​H2SO4 solution interface: Gravimetric,electrochemical, SEM and EDX studies

The inhibition performance of five azomethine derivatives such as: 1-(4-Methyloxy phenylimino)-1-(phenylhydrazono)-propan-2-one (SB₁), 1-(4-Methylphenylimino)-1-(phenylhydrazono) propan-2-one (SB₂), 1-(phenylimino)-1(phenylhydrazono)-propan-2-one (SB₃), 1-(4-Bromo phenylimino)-1(phenylhydrazono)-propan-2-one (SB₄) and 1-(4-Chlorophenylimino)-1(phenylhydrazono) -propan-2-on (SB₅) as corrosion inhibitors for mild steel in sulfuric acid 0.5 ?M were investigated using different methods. All experimental results demonstrate that these compounds are eficients inhibitors. The inhibition efficiencies ($IE$) increase with inhibitors concentration. At 7.5 $\times$ 10^?5 ?M, the $IE$ was 97.27%, 96.31%, 94.23%, 93.19 and 91.64% for SB₁, SB₂, SB₃, SB₄ and SB₅, respectively. The potentiodynamic polarization results indicated that all the studied inhibitors act as mixed type. The adsorption process on mild steel surface obeyed Langmuir isotherm. The associated activation parameters and thermodynamic have been calculated and discussed. The adsorbed film formed on the metal surface was characterized by SEM and EDX.     

Experimental,Monte Carlo and molecular dynamics simulations to investigate corrosion inhibition of mild steel in hydrochloric acid solutions

The efficiency of three furan derivatives, namely 2-(p-toluidinylmethyl)-5-methyl furan (Inh. A), 2-(p-toluidinylmethyl)-5-nitro furan (Inh. B) and 2-(p-toluidinylmethyl)-5-bromo furan (Inh. C), as possible corrosion inhibitors for mild steel in 1.0 M HCl, has been determined by weight loss and electrochemical measurements. These compounds inhibit corrosion even at very low concentrations, and 2-(p-toluidinylmethyl)-5-methyl furan (Inh. A) is the best inhibitor. Polarization curves indicate that all compounds are mixed-type inhibitors, affecting both cathodic and anodic corrosion currents. Adsorption of furan derivatives on the mild steel surface follows the Langmuir adsorption isotherm, and the calculated Gibbs free energy values confirm the chemical nature of the adsorption. Monte Carlo simulations technique incorporating molecular mechanics and molecular dynamics can be used to simulate the adsorption of furan derivatives on mild steel surface in 1.0 M HCl.     

Synergistic inhibition effects between leaves and stem extracts of Sida acuta and iodide ion for mild steel corrosion in 1 M H2SO4 solutions

The synergistic action caused by iodide ions on the corrosion inhibition of mild steel in 1 M H₂SO₄ by leaves and stem extracts of Sida acuta was studied using weight loss and hydrogen evolution methods at 30–60 °C. It was found that the leaves and stem extracts of S. acuta inhibited the acid induced corrosion of mild steel. Addition of iodide ions enhances the inhibition efficiency to a considerable extent. The inhibition efficiency increases with increase in the iodide ion concentration but decreases with rise in temperature. Adsorption of the extracts alone and in combination of iodide ion was found to obey Freundlich adsorption isotherm at all temperatures studied. Inhibition mechanism is deduced from the temperature dependence of the inhibition efficiency as well as from assessment of kinetic and activation parameters that govern the processes. The synergism parameter (S₁) is defined and evaluated from the inhibition efficiency values. This parameter for the different concentrations of iodide ions from the two techniques employed is found to be greater than unity indicating that the enhanced inhibition efficiency of the extracts caused by the addition of iodide ions is due to synergism.     

Electrochemical studies for the electroactivity of amine-capped aniline trimer on the anticorrosion effect of as-prepared polyimide coatings

The electroactive polyimide consisting of various content of amine-capped aniline trimers (ATs) have been successfully synthesized and characterized by Fourier-Transformation infrared and UV-visible absorption spectroscopy. The electroactivity of as-prepared polyimides was tested by electrochemical cyclic voltammetry (CV) studies. It was noticed that the as-prepared electroactive polyimide with higher content of amine-capped ATs shows higher electroactivity (i.e., larger redox current) than that of non-electroactive polyimide, leading to enhance corrosion protection efficiency on cold-rolled steel (CRS) electrodes. This enhanced corrosion protection efficiency has been explained based on a series of electrochemical measurements such as corrosion potential, polarization resistance, corrosion current and electrochemical impedance spectroscopy (EIS) studies in 5 wt-% NaCl electrolyte. This significant enhancement of corrosion protection on CRS electrodes as compared to non-electroactive polyimide might probably be attributed to the redox catalytic property of as-prepared electroactive polyimide coatings inducing the formation of passive layer of metal oxide.     

Experimental and theoretical investigation of adsorption and inhibition properties of 2-Amino-1,3,5-triazine-4,6-dithiol against corrosion in hydrochloric acid solution on mild steel

In this work, 2-Amino-1,3,5-triazine-4,6-dithiol (2-ATD) as novel and high efficiency corrosion inhibitor has been investigated for mild steel (MS) corrosion in 0.5 M HCl solution using electrochemical methods, scanning electron microscopy (SEM), energy disperse X-ray spectroscopy (EDX), atomic force microscopy (AFM) and quantum chemical calculation methods. Potentiodynamic polarization (PDP) curves indicate that 2-ATD is mixed type inhibitor, corrosion inhibition efficiency increased with increasing inhibitor concentration and reached its value of 96.5%. Evolution of exposure time versus corrosion behavior of 2-ATD is examined in corrosive medium. While corrosion potential (E_corr) shifted more negative values, polarization resistances (R_p) decreased after 120 h exposure time due to the corrosion process. H₂ volume is measured in uninhibited and inhibited solutions (10 mM 2-ATD) after 120 h exposure time. Very low volume (3.6 mL cm⁻²) of H₂ is obtained on MS electrode in inhibited solution after 120 h of exposure, indicating that 2-ATD covers the entire surface against aggressive attack and retards the both anodic dissolution of MS and cathodic hydrogen evolution reactions. The adsorption process proposal is the Langmuir isotherm which is most suitable. Adsorption and thermodynamic parameters show that 2-ATD has a strong adsorption effect onto MS surface and includes mixed adsorption style (physical and chemical). Corrosion current density increases with increasing temperature and high activation energy (Ea) proves the strong adsorption of 2-ATD on the MS surface. Anti-corrosion mechanism of 2-ATD is described more detail with the potential of zero charge method. SEM, EDX and AFM analysis support the obtained results of electrochemical methods and confirm the existence of protective layer and strong adsorption of 2-ATD on the MS surface. Chronoamperometry test shows that current densities are almost constant whole experiment in the presence of organic film. Finally, quantum chemical calculation method of 2-ATD in blank solution is performed to investigate the active sites for possible attachment with MS surface.     

Inhibition of aluminium and mild steel corrosion in acidic medium using Gum Arabic

The corrosion behaviour of mild steel and aluminium exposed to H₂SO₄ solution and their inhibition in H₂SO₄ containing 0.1–0.5 g/L Gum Arabic (GA) used as inhibitor was studied at temperature range of 30–60 °C using weight loss and thermometric techniques. Corrosion rate increased both in the absence and presence of inhibitor with increase in temperature. Corrosion rate was also found to decrease in the presence of inhibitor compared to the free acid solution. Inhibition efficiency increases with increase in concentration of the inhibitor reaching a maximum of 37.88% at 60 °C for mild steel and 79.69% at 30 °C for aluminium at 0.5 g/L concentration of GA. The inhibitor, GA was found to obey Temkin and El-Awady et al. thermodynamic kinetic adsorption isotherm for mild steel and aluminium respectively from the fit of the experimental data at all concentrations and temperatures studied. The phenomenon of chemical adsorption is proposed for mild steel corrosion, while physical adsorption mechanism is proposed for aluminium corrosion. Results obtained for the kinetic/thermodynamic studies indicate that the adsorption of GA onto the metals surface was spontaneous. GA is a better corrosion inhibitor for aluminium than for mild steel.     

Synthesis,characterization and corrosion inhibition efficiency of 2-(6-methylpyridin-2-yl)-1H-imidazo[4,5-f][1,10] phenanthroline on mild steel in sulphuric acid

Phenanthroline derivative, 2-(6-methylpyridin-2-yl)-1H-imidazo[4,5-f][1,10] phenanthroline (MIP) was synthesized and characterized by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, and single crystal X-ray diffraction study. MIP was evaluated as corrosion inhibitor for mild steel in 0.5 M H₂SO₄ solution using gravimetric and UV–Visible spectrophotometric methods at 303–333 K. Results obtained show that MIP acts as inhibitor for mild steel in H₂SO₄ solution. The inhibition efficiency was found to increase with increase in MIP concentration but decreased with temperature. Activation parameters and Gibbs free energy for the adsorption process using statistical physics were calculated and discussed. The UV–Visible absorption spectra of the solution containing the inhibitor after the immersion of mild steel specimen indicate the formation of a MIP-Fe complex.     

Xanthione: A new and effective corrosion inhibitor for mild steel in sulphuric acid solution

The adsorption and inhibition effect of xanthione (XION) on mild steel in 0.5 M H₂SO₄ at 303–333 K were studied using gravimetric and UV–visible spectrophotometric methods. The results obtained show that XION acts as an effective corrosion inhibitor for mild steel in sulphuric acid and inhibition efficiency reaches 98.0% at a very low inhibitor concentration of 10 μM. Inhibition efficiency was found to increase with increase in XION concentration but decreased with temperature suggesting physical adsorption mechanism. Arrhenius law and its transition equation lead to estimate the activation parameters of the corrosion process. XION inhibits the corrosion of mild steel effectively at moderate temperature and adsorbs according to the Langmuir isotherm. Thermodynamic parameters governing the adsorption process have been calculated and discussed. The UV–visible absorption spectra of the solution containing the inhibitor after the immersion of mild steel specimen indicate the formation of a XEN–Fe complex. Attempt to correlate the molecular structure to quantum chemical indices was made using density functional theory (DFT).     

An experimental and theoretical investigation on adsorption properties of some diphenolic Schiff bases as corrosion inhibitors at acidic solution/mild steel interface

The effect of novel synthesized three Schiff bases, namely, 1,3-bis[2-(2-hydroxy benzylidenamino) phenoxy] propane (P1), 1,3-bis[2-(5-chloro-2-hydroxybenzylidenamino) phenoxy] propane (P2), and 1,3-bis[2-(5-bromo-2-hydroxybenzylidenamino) phenoxy] propane (P3), on the corrosion of mild steel in 0.1 M HCl was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy methods. Polarization measurements suggest that P1 acts as mixed type inhibitor while P2 and P3 behave as mainly cathodic inhibitors for acidic corrosion of steel. All electrochemical measurements show that inhibition efficiencies increase with increase in inhibitor concentration. This reveals that inhibitive actions of inhibitors were mainly due to adsorption on steel surface. Adsorption of these inhibitors follows Temkin adsorption isotherm. The correlation between the adsorption ability of inhibitors and their molecular structures has been investigated using quantum chemical parameters obtained by MNDO semi-empirical method. Calculated quantum chemical parameters indicate that Schiff bases adsorbed on steel surface by chemical mechanism.     

Investigation on corrosion inhibition effect of N-[4-(1,3-benzo[d]thiazol-2-ylcarbamoyl)phenyl]quinoline-6-carboxamide as a novel organic inhibitor on mild steel in 1N HCl at different temperatures: Experimental and theoretical study

A new novel organic corrosion inhibitor N-[4-(1,3-benzo[d]thiazol-2-ylcarbamoyl)phenyl]quinoline-6-carboxamide (NBCPQC) has been synthesized. The synthesized novel organic inhibitor NBCPQC used to be carried out on mild steel corrosion in 1N HCl for the first time. The studied inhibitor was once evaluated as corrosion inhibitor for mild steel in 1N of HCl solution using electrochemical research which advocated that a protective film is form by the process of inhibitor absorption on the surface of mild steel. Inhibitor shows a better inhibiton efficiency of maximum above 90% in 1N HCl medium. Inhibitors show a better efficiency by way of reducing and sluggish down the corrosion process however on growing the temperature it is weakened on controlling corrosion. In addition to this adsorption isothermal models had been interpreted to fit the adsorption behaviour of the inhibitor compound on mild steel surface. Thus the result reveals that the compound shows a Langmuir adsorption isotherm.     

Kinetic approach to mild steel corrosion

Summary The rate of steel corrosion in hydrochloric acid solutions in the absence and in the presence of inhibitors is studied. It is found that the process dynamics is described by an exponential kinetic equation of self-accelerating reactions in the absence of inhibitor and by an equation of a zero order in its presence.     

Adsorption behavior and corrosion inhibitive potential of xanthene on mild steel/sulphuric acid interface

The inhibition of xanthene (XEN) on the corrosion of mild steel in 0.5 M H₂SO₄ was studied by gravimetric and UV–visible spectrophotometric methods at 303–333 K. Results obtained show that XEN act as inhibitor for mild steel in H₂SO₄ solution. The inhibition efficiency was found to increase with increase in XEN concentration but decreased with temperature. Activation parameters and Gibbs free energy for the adsorption process using Statistical Physics were calculated and discussed. The corrosion process in 0.5 M H₂SO₄ in the absence and presence of XEN follows zero-order kinetics. The UV–visible absorption spectra of the solution containing the inhibitor after the immersion of mild steel specimen indicate the formation of a XEN–Fe complex. Quantum chemical calculations using DFT were used to calculate some electronic properties of the molecule in order to ascertain any correlation between the inhibitive effect and molecular structure of xanthene.     

Corrosion inhibition studies on mild steel in HCl by a newly synthesized benzil monohydrazone based Schiff base

The corrosion inhibition effect of newly formulated Schiff base 2-((E)-((E)-2-hydrazone-1, 2-diphenylethylidene) amino phenol) (HDAP) ligand L derived from Benzil monohydrazone and 2-Aminophenol on mild steel in 1 ​M HCl was examined. Electrochemical (Tafel and EIS) and mass loss techniques were employed to evaluate its corrosion protection efficiency. The inhibition efficiency (η %) was elevated with raise in concentration of compound L.Maximum inhibition efficiency of 94.18% was obtained at 0.01 ​M concentration of HDAP from Tafel polarisation curve. From electrochemical impedance (EIS) studies, it was confirmed that increase in concentration of HDAP led to enhancement of the charge transfer resistance. Both physical and chemical types of adsorptions were observed for the Schiff base via π-bonding electrons which obey Langmuir adsorption isotherm. The SEM picture revealed development of a thin layer on metallic surface. Quantum chemical evaluations were conducted to find out the mechanism of corrosion retardation power of HDAP.