Investigation of the inhibitive effect of ortho-substituted anilines on corrosion of iron in 1 M HCl solutions

The inhibitory activity of some o-substituted anilines on iron corrosion in hydrochloric acid (HCl) was studied in relation to inhibitor concentration using potentiodynamic and electrochemical impedance spectroscopy (EIS) measurements. O-substituted anilines were found to act as mixed type inhibitors. The results showed that o-substituted anilines suppressed both cathodic and anodic processes of iron corrosion in 1 M HCl by its adsorption on the iron surface according to Langmuir adsorption isotherm. Potentiodynamic and EIS measurements reveal that these compounds inhibit the iron corrosion in 1 M HCl and that the efficiency increases with increasing of the inhibitor concentration. Data obtained from EIS are analyzed to model the corrosion inhibition process through equivalent circuit.     

Ortho-substituted anilines to inhibit copper corrosion in aerated 0.5 M hydrochloric acid

Aniline derivatives, namely 2-chloroaniline, 2-fluoroaniline, 2-aminophenetole, 2-ethylaniline, o-aminoanisole and o-toluidine were studied for their possible use as copper corrosion inhibitors in 0.5 M HCl. These compounds were studied in concentrations from 10⁻³ to 10⁻⁴ M at temperature 298 K. Effectiveness of these compounds was assessed through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. These compounds inhibit the corrosion of copper in HCl solution to some extent. In each case, inhibition efficiencies increase with increasing concentration. A suggested model for the interface as well as some kinetic data is presented. These inhibitors obey the Temkin adsorption isotherm. A correlation between structure and inhibition efficiencies is suggested.     

Corrosion inhibition of aluminium in acid solutions by some imidazoline derivatives

2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI) were synthesized and characterized by FT-IR and NMR Studies. The corrosion inhibition properties of these compounds on aluminium in 1 M HCl and 0.5 M H₂SO₄ were investigated by weight loss, potentiodynamic polarization, electrochemical impedance and scanning electron microscopic techniques. The weight loss study showed that the inhibition efficiency increases with increase in the concentration of the inhibitor and was found to be inversely related to time and temperature while it shows no significant change with increase in acid concentration. The effectiveness of these inhibitors were in the order of UDI > NI > PDI > HDI .The values of activation energy, free energy of adsorption, heat of adsorption, enthalpy of activation and entropy of activation were also calculated to elaborate the mechanism of corrosion inhibition. The adsorption of these compounds on aluminium surface follows the Langmuir adsorption isotherm. The potentiodynamic polarization data show that the compounds studied are mixed type inhibitors. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The surface characteristics of inhibited and uninhibited metal samples were investigated by scanning electron microscopy (SEM).     

Amphiphilic amido-amine as an effective corrosion inhibitor for mild steel exposed to CO2 saturated solution: Polarization, EIS and PM-IRRAS studies

The corrosion behavior of mild steel in CO₂-saturated 5% NaCl solution with N-[2-[(2-aminoethyl) amino] ethyl]-9-octadecenamide corrosion inhibitor at 25 °C has been studied by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) measurements. Both potentiodynamic polarization and EIS measurements reveal that this amido-amine precursor inhibits the carbon steel corrosion and the inhibition efficiency increases with increasing the inhibitor concentration. The corrosion inhibitor exhibits high corrosion efficiencies as a mixed-type inhibitor, with a predominant influence on the anode process. The organic inhibitor acts blocking surface sites at low concentrations and by modifying the adsorption mechanism forming a protective barrier against corrosive ions at high concentrations. EIS results show that the mechanism of its corrosion inhibition at concentrations higher than 0.82 × 10⁻⁵ M is by forming a protective bilayer with small pore sizes that hinders the passage of the reactive species. PM-IRRAS measurements demonstrate that the inhibitor is chemisorbed to surface steel. Therefore, its spectrum reveals that the inhibitor monolayer has an amorphous structure.     

Studies of iron corrosion inhibition using chemical, electrochemical and computer simulation techniques

The inhibitive action of some benzimidazole derivatives namely 2-(2-furanyl)-1H-benzimidazole (FB), 2-(2-pyridyl) benzimidazole (PB) and 2-(4-thiazolyl) benzimidazole (TB), against the corrosion of iron in solutions of nitric acid has been studied using density function theory calculations (DFT), weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The calculated electronic parameters involved in the activity of the benzimidazole derivatives confirmed that the position of the side chain in the benzimidazole moiety affects the pattern of activity. The effectiveness of the benzimidazole derivatives is following the order TB > PB > FB. The same order is supported by the experimental chemical and electrochemical measurements. The relationships between inhibition efficiency of iron in 1.0 M HNO₃ and the molecular orbitals of the studied molecules as well as number of electrons transferred ΔN from the inhibitor molecules to the iron surface were calculated by DFT method. The inhibition efficiency increased with the increase in E_HOMO and decrease in E_LUMO-E_HOMO. TB had the highest inhibition efficiency because it had the highest HOMO energy and ΔN values, and it was most capable of offering electrons. Molecular modeling was used to evaluate the structural, electronic and reactivity parameters of the selected benzimidazole derivatives in relation to their effectiveness as corrosion inhibitors. Results obtained from weight loss, dc polarization and ac impedance measurements are in reasonably good agreement and show increased inhibitor efficiency with increasing inhibitor concentration.Data obtained from EIS were analyzed to model the corrosion inhibition process through equivalent circuit.     

Molecular simulation, quantum chemical calculations and electrochemical studies for inhibition of mild steel by triazoles

The inhibition performance of three triazole derivatives on mild steel in 1 M HCl were tested by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The adsorption behavior of these molecules at the Fe surface was studied by the molecular dynamics simulation method and the quantum chemical calculations. Results showed that these compounds inhibit the corrosion of mild steel in 1 M HCl solution significantly. Molecular simulation studies were applied to optimize the adsorption structures of triazole derivatives. The iron/inhibitor/solvent interfaces were simulated and the charges on the inhibitor molecules as well as their structural parameters were calculated in presence of solvent effects. Aminotriazole was the best inhibitor among the three triazole derivatives (triazole, aminotriazole and benzotriazole). The adsorption of the inhibitors on the mild steel surface in the acid solution was found to obey Langmuir's adsorption isotherm.     

Inhibition by <Emphasis Type="Italic">Jasminum nudiflorum</Emphasis> Lindl. leaves extract of the corrosion of cold rolled steel in hydrochloric acid solution

The inhibition effect of Jasminum nudiflorum Lindl. leaves extract (JNLLE) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) was investigated by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results show that JNLLE acts as a very good inhibitor, and the inhibition efficiency increases with the concentration of JNLLE. The adsorption of JNLLE obeys Langmuir adsorption isotherm. Values of inhibition efficiency obtained from weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) are in good agreement. Polarization curves show that JNLLE behaves as a mixed-type inhibitor in hydrochloric acid. EIS shows that charge-transfer resistance increase and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The adsorbed film on CRS surface containing JNLLE inhibitor was also measured by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). A probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

Corrosion inhibition and adsorption properties of cerium-amino acid complexes on mild steel in acidic media: Experimental and DFT studies

Abstract

The corrosion inhibition and adsorption behavior of glutamic acid (Glu), glutamine (Gln), and their cerium complexes: cerium glutamate (Ce(Glu)) and cerium glutamine (Ce(Gln)) on mild steel in 0.5?M HCl solutions were studied at 25 and 55?°C and concentration range of 25–200?ppm using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopic (EIS) techniques. The inhibition efficiency was found to be dependent on the concentration and temperature of the system. The potentiodynamic polarization results suggest that the compounds act as mixed-type inhibitors with dominant cathodic inhibition. The mechanism of adsorption deduced from the variation of inhibition efficiency with temperature, as well as the activation parameters, suggest significant physisorption of the inhibitor molecules on the metal surface. The experimental data adhere to the Langmuir and El-Awady et al. kinetic adsorption models. The extent of inhibition was found to be Ce-Gln?>?Gln and Ce-Glu?>?Glu. The scanning electron microscope was employed for the morphological studies and the characteristic of the protective layer on the steel surface verified using UV-Vis spectroscopy and FTIR spectroscopy. Adsorption of the inhibitors on Fe (110) surface was evaluated theoretically.     

1-(2-Hydroxyethyl)-2-imidazolidinone as corrosion inhibitor of mild steel in 0.5 M HCl solution: thermodynamic,electrochemical and theoretical studies

The inhibition effect of 1-(2-Hydroxyethyl)-2-imidazolidinone (2-HEI) on mild steel (MS) corrosion in 0.5?M HCl solution was investigated at different inhibitor concentration and temperature by electrochemical experiments, such as linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and quantum chemical calculations. The inhibitor adsorption process on mild steel in 0.5?M HCl system was studied at different temperatures (20?°C–50?°C). Furthermore, the surface morphology of MS was also investigated with SEM in the absence and the presence of inhibitor. The adsorption of 1-(2-Hydroxyethyl)-2-imidazolidinone on MS surface is an exothermic process and this process obeys the Langmuir adsorption isotherm. The Quantum chemical findings are good agreed with the empirical data.     

Eco friendly corrosion inhibitors: Inhibitive action of quinine for corrosion of low carbon steel in 1 m HCl

Quinine, a natural product, was investigated as a corrosion inhibitor for low carbon steel in 1.0 m HCl solution. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to study the inhibition action in the temperature range 20–50 °C. The corrosion of steel was controlled by a charge transfer process at the prevailing conditions. The electrochemical results showed that quinine is an efficient inhibitor for low carbon steel and an efficiency up to 96% was obtained at 20 °C. The inhibition efficiency increases with inhibitor concentration and reaches a near constant value in the concentration range 0.48 mM and above. Application of the Langmuir adsorption isotherm enabled a study of the extent and the mode of adsorption.     

Investigation of adsorption and inhibitive effect of 2-mercaptothiazoline on corrosion of mild steel in hydrochloric acid media

The inhibition effect of 2-mercaptothiazoline (2MT) on the corrosion behavior of mild steel (MS) in 0.5 M HCl solution was studied in both short and long immersion times (120 h) using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. For long-term tests, hydrogen gas evolution (VH₂−t) and the change of the open circuit potential with immersion time (E_ocp − t) were also measured in addition to the former three techniques. The surface morphology of the MS after its exposure to 0.5 M HCl solution with and without 1.0 × 10⁻² M 2MT with the different immersion times was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thermal stability of the inhibitor film was investigated by thermogravimetric analysis (TGA). The value of activation energy (E_a) for the MS corrosion and the thermodynamic parameters such as adsorption equilibrium constant (K_ads), free energy of adsorption (ΔG_ads), adsorption heat (ΔH_ads) and adsorption entropy (ΔS_ads) values were calculated and discussed. The potential of zero charge (PZC) of the MS in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. The results showed that 2MT performed excellent inhibiting effect for the corrosion of the MS. Finally, the high inhibition efficiency was discussed in terms of adsorption of inhibitor molecules and protective film formation on the metal surface. TGA results also indicated that the inhibitor film on the surface had a relatively good thermal stability.     

Adsorption properties and inhibition of mild steel corrosion in hydrochloric acid solution by ceftobiprole

The inhibition effect of ceftobiprole against the corrosion of mild steel in 1 M HCl solution was studied by weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and atomic force microscopy techniques. Inhibition efficiency increased with inhibitor concentration where as decreased with acid concentration. Data obtained from EIS studies were analyzed to model the corrosion inhibition process through appropriate equivalent circuit models. The adsorption of ceftobiprole obeyed Langmuir adsorption isotherm. Both thermodynamic and activation parameters were calculated and discussed. Polarization curves indicated that they are mixed type of inhibitors. Polarization curves showed that ceftobiprole act as mixed-type inhibitor. The results obtained from weight loss, EIS and Potentiodynamic polarization are in good agreement.     

Synthesis,Characterization and Inhibition Performance of Vanillin‐Modified Chitosan Quaternary Ammonium Salts for Q235 Steel Corrosion in HCl Solution

In order to enhance the solubility of chitosan in water and its corrosion inhibition performance on Q235 steel in 1 M HCl solution, N‐vanillyl‐O‐2′‐hydroxypropyltrimethylammonium chloride chitosan (VHTC) was synthesized. The structure of VHTC was characterized by FT‐IR and ¹H‐NMR spectroscopy. The corrosion inhibition performance of VHTC on Q235 steel in 1 M HCl solution was studied by weight loss, polarization, electrochemical impedance spectroscopy (EIS) and stereo microscope analysis. Experimental results indicate that VHTC shows better inhibition efficiency compared to chitosan. When the concentration of VHTC increases to 200 mg L^?1, the inhibition efficiency reaches 90 %, which is almost equal to the conventional corrosion inhibitors (e.g., imidazoline). The polarization study demonstrates that VHTC is a mixed‐type inhibitor caused by a geometrical blanketing effect. The charge transfer resistance is proportional to the inhibitor concentration as revealed by the EIS results, indicating that the protective film on the Q235 steel surface is formed by adsorption of the inhibitor molecules. The inhibition efficiency of VHTC achieves the maximum value within 24 h when the concentration of VHTC is 200 mg L^?1. The morphology observation of the corroded steel surface indicates that the corrosion of Q235 steel in 1 M HCl solution is significantly inhibited after introducing VHTC into the acidic solution.     

New synthesised pyridazine derivatives as effective inhibitors for the corrosion of pure iron in HCl medium

The inhibition of pure iron in 1 M HCl by new synthesised pyridazine compounds has been studied by weight loss, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. The results obtained reveal that these compounds are efficient inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration and reached 98% at 10⁻⁴ M for 5-benzyl-6-methyl pyridazine-3-thione. Potentiodynamic polarisation studies clearly reveal that the presence of pyridazines does not change the mechanism of hydrogen evolution and that they act essentially as cathodic inhibitors. The temperature effect on the corrosion behaviour of pure iron in 1 M HCl without and with the pyridazines at 10⁻⁴ M was studied in the temperature range from 298 to 353 K. EIS measurements show that the increase of the transfer resistance with the inhibitor concentration.     

THE ROLE OF PHOSPHONATE DERIVATIVES ON THE CORROSION INHIBITION OF STEEL IN HCL MEDIA

The inhibition of corrosion of steel by two P-containing compounds, sodium methyldodecyl phosphonate and sodium methyl (11-smethacryloyloxyundecyl) phosphonate, in hydrochloric acid has been investigated at various temperatures using electrochemical techniques (impedance spectroscopy (EIS), potentiodynamic polarization) and weight loss measurements. Inhibition efficiency (E%) increased with phosphonate concentration. Adsorption of inhibitors on the steel surface in 1 M HCl follows the Langmuir isotherm model. EIS measurements showed that the dissolution process of steel occurred under activation control. Polarization curves indicated that inhibitors tested acted as cathodic inhibitors. The temperature effect on the corrosion behavior of steel in 1 M HCl without and with the inhibitor was studied in the temperature range from 313 to 353 K. The adsorption free energy and activation parameters for the steel dissolution reaction in the presence of phosphonates were determined.     

THE ROLE OF PHOSPHONATE DERIVATIVES ON THE CORROSION INHIBITION OF STEEL IN HCL MEDIA

The inhibition of corrosion of steel by two P-containing compounds, sodium methyldodecyl phosphonate and sodium methyl (11-smethacryloyloxyundecyl) phosphonate, in hydrochloric acid has been investigated at various temperatures using electrochemical techniques (impedance spectroscopy (EIS), potentiodynamic polarization) and weight loss measurements. Inhibition efficiency (E%) increased with phosphonate concentration. Adsorption of inhibitors on the steel surface in 1 M HCl follows the Langmuir isotherm model. EIS measurements showed that the dissolution process of steel occurred under activation control. Polarization curves indicated that inhibitors tested acted as cathodic inhibitors. The temperature effect on the corrosion behavior of steel in 1 M HCl without and with the inhibitor was studied in the temperature range from 313 to 353 K. The adsorption free energy and activation parameters for the steel dissolution reaction in the presence of phosphonates were determined.     

Synthesis of Environmentally Friendly Highly Dispersed Magnetite Nanoparticles Based on Rosin Cationic Surfactants as Thin Film Coatings of Steel

This work presents a new method to prepare monodisperse magnetite nanoparticles capping with new cationic surfactants based on rosin. Core/shell type magnetite nanoparticles were synthesized using bis-N-(3-levopimaric maleic acid adduct-2-hydroxy) propyl-triethyl ammonium chloride (LPMQA) as capping agent. Fourier transform infrared spectroscopy (FTIR) was employed to characterize the nanoparticles chemical structure. Transmittance electron microscopies (TEM) and X-ray powder diffraction (XRD) were used to examine the morphology of the modified magnetite nanoparticles. The magnetite dispersed aqueous acid solution was evaluated as an effective anticorrosion behavior of a hydrophobic surface on steel. The inhibition effect of magnetite nanoparticles on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Results obtained from both potentiodynamic polarisation and EIS measurements reveal that the magnetite nanoparticle is an effective inhibitor for the corrosion of steel in 1.0 M HCl solution. Polarization data show that magnetite nanoparticles behave as a mixed type inhibitor. The inhibition efficiencies obtained from potentiodynamic polarization and EIS methods are in good agreement.     

Adsorption and inhibitive action of hexadecylpyridinium bromide on steel in phosphoric acid produced by dihydrate wet method process

The adsorption and inhibitive action of hexadecylpyridinium bromide (HDPB) on the corrosion of cold rolled steel (CRS) in phosphoric acid produced by dihydrate wet method process (7.0 M H₃PO₄) was studied by weight loss, open circuit potential (OCP), potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and atomic force microscopy (AFM) methods. The results show that HDPB is a good inhibitor in 7.0 M H₃PO₄, and its maximum inhibition efficiency (IE) is higher than 90% at little concentrations. The adsorption of HDPB obeys Langmuir adsorption isotherm equation. Thermodynamic parameters (adsorption enthalpy ∆H ⁰, adsorption free energy ∆G ⁰, and adsorption entropy ∆S ⁰) were calculated and discussed. Polarization curves show that HDPB acts as a mixed-type inhibitor in phosphoric acid. EIS shows that charge-transfer resistance increases with the inhibitor concentration, confirming adsorption process mechanism. The inhibition action of HDPB could also be evidenced by SEM and AFM images. A probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

4-Aminoantipyrine as an inhibitor of mild steel corrosion in HCl solution

4-aminoantipyrine (AAP) was tested as a corrosion inhibitor for mild steel in 2 M HCl solution using different techniques: weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that AAP is an inhibitor for mild steel in this medium. The inhibition was assumed to occur via adsorption of the inhibitor molecule on the metal surface. In the 20 to 60 C temperature range, the AAP adsorption follows the Flory–Huggins isotherm and/or the El-Awady et al. kinetic-thermodynamic model. The protection efficiency increases with increasing inhibitor concentration (in the range 10–310–2 M) but decreases with increasing temperature. The thermodynamic functions of dissolution and adsorption processes were calculated.     

Piperazine derivatives as inhibitors of the corrosion of mild steel in 3.9 M HCl

The inhibitory action of two piperazine derivatives, 1-benzyl piperazine (P1) and bis(1-benzylpiperazine) thiuram disulfide (P2) on the corrosion of mild steel in 3.9 M HCl at different concentrations has been investigated in the temperature domain 298–333 K. Both weight loss measurements and potentiodynamic polarization methods showed that P2 was the best inhibitor and that its inhibition efficiency increased with concentration to a value >92% at 10⁻³ M. Potentiodynamic polarization studies clearly revealed that P2 acts as cathodic-type inhibitor. The activation energy for the corrosion rates was evaluated in the temperature range 298–333 K. Adsorption of P2 on the mild steel surface in 3.9 M HCl followed a Langmuir isotherm model. A physical adsorption phenomenon is proposed.