On the inhibition of mild steel corrosion by 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol

The corrosion inhibition of mild steel in a 2.5 M H₂SO₄ solution by 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol (APTT) was studied at different temperatures, utilising open circuit potential, potentiodynamic and impedance measurements. The results indicate that APTT performed as an excellent mixed-type inhibitor for mild steel corrosion in a 2.5 M H₂SO₄ solution and that the inhibition efficiencies increased with the inhibitor concentration but decreased proportionally with temperature. The kinetic and thermodynamic parameters for adsorption of APTT on the mild steel surface were calculated. A chemisorption mechanism of APTT molecules on the mild steel surface was proposed based on the thermodynamic adsorption parameters.     

Inhibiting effects of butyl triphenyl phosphonium bromide on corrosion of mild steel in 0.5 M sulphuric acid solution and its adsorption characteristics

Butyl triphenyl phosphonium bromide (BuTPPB) has been evaluated as a corrosion inhibitor for mild steel in 0.5 M H₂SO₄ solutions using galvanostatic polarisation and potentiostatic polarisation measurements. The study was also complemented by infra red (IR) spectroscopy, scanning electron microscopy (SEM) and quantum chemical calculations. Galvanostatic polarisation measurements showed that the presence of BuTPPB in aerated 0.5 M H₂SO₄ solutions decreases corrosion currents to a great extent and the corrosion rate decreases with increasing inhibitor concentration at a constant temperature. At 298K, inhibition efficiency was found to be 94.5% for 10⁻⁷ M BuTPPB which increased to about 99% for the BuTPPB concentration of 10⁻² M. The effect of temperature on the corrosion behaviour of mild steel was studied at five different temperatures ranging from 298 to 338K. The polarisation curves clearly indicate that BuTPPB acts as a mixed type inhibitor. Adsorption of BuTPPB on the mild steel surface follows the Langmuir isotherm.Potentiostatic polarisation measurements showed that passivation was observed only for lower BuTPPB concentrations (10⁻⁵ and 10⁻⁷ mol l⁻¹) for the mild steel in 0.5 M H₂SO₄. IR and SEM investigations also confirmed the adsorption of BuTPPB on the mild steel surface in 0.5 M H₂SO₄ solutions. The molecular parameters obtained using PM3 semi-empirical method, were correlated with the experimentally measured inhibitor efficiencies.     

N-Aminorhodanine as an effective corrosion inhibitor for mild steel in 0.5 M H2SO4

The corrosion inhibition effect of N-aminorhodanine (N-AR) on mild steel (MS) in 0.5 M H₂SO₄ was studied in both short and long immersion duration using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), chronoamperometry and hydrogen gas evolution. The surface morphology of MS was examined with scanning electron microscopy (SEM) in absence and presence inhibitor. The inhibitor adsorption process on MS surfaces obeys the Langmuir adsorption isotherm. The results show that NAR is a good inhibitor for MS in the acidic medium. The inhibition efficiency obtained from potentiodynamic polarization, EIS and LPR up to 98% is determined.     

Alizarin violet 3B as a novel corrosion inhibitor for steel in HCl, H2SO4 solutions

The inhibition effect of alizarin violet 3B (AV3B) on the corrosion of cold rolled steel (CRS) in 1.0 M HCl and 0.5 M H₂SO₄ solutions was investigated for the first time by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The results show that AV3B is a good inhibitor, and exhibits more efficient in 1.0 M HCl than 0.5 M H₂SO₄. The adsorption of AV3B on CRS surface obeys Langmuir adsorption isotherm in both acids. Polarization curves reveal that AV3B acts as a mixed-type inhibitor.     

Triazolyl blue tetrazolium bromide as a novel corrosion inhibitor for steel in HCl and H2SO4 solutions

The inhibition effect of triazolyl blue tetrazolium bromide (TBTB) on the corrosion of cold rolled steel (CRS) in 1.0 M HCl and 0.5 M H₂SO₄ solution was investigated for the first time by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. The results show that TBTB is a very good inhibitor, and is more efficiency in 1.0 M HCl than 0.5 M H₂SO₄. The adsorption of TBTB on CRS surface obeys Langmuir adsorption isotherm. Polarization curves reveal that TBTB acts as a mixed-type inhibitor in both acids.     

Effect of 2,2′ benzothiazolyl disulfide on the corrosion of mild steel in acid media

2,2′ benzothiazolyl disulfide (BTDS) has been synthesised and their inhibiting action on mild steel corrosion in 1 M HCl and 0.5 M H₂SO₄ at 308 K has been investigated using weight loss, EIS, polarization and SEM study. BTDS showed better efficiency in 0.5 M H₂SO₄ compared to 1 M HCl. Polarization studies revealed that BTDS is a mixed type inhibitor in both acids predominantly cathodic in 1 M HCl where as predominantly anodic in 0.5 M H₂SO₄. Thermodynamic parameters i.e. free energy of adsorption, enthalpy, entropy and activation energy were calculated, the values of these parameters showed good interaction.     

Substitutional adsorption isotherms and corrosion inhibitive properties of some oxadiazol-triazole derivative in acidic solution

A newly synthesized oxadiazol-triazole derivative (TOMP), was investigated as corrosion inhibitor of mild steel in 0.5 M H₂SO₄ solution using weight loss measurements, polarization and electrochemical impedance spectroscopy (EIS) methods. Results obtained revealed that TOMP is effective corrosion inhibitor for mild steel in sulphuric acid and its efficiency attains more than 97.6% at 298 K. The number of water molecules (X) replaced by a molecule of organic adsorbate was determined from the substitutional adsorption isotherms applied to the data obtained from the weight loss experiments performed on mild steel specimen in acidic solution in the 298-333 K range.     

Adsorption and inhibitive properties of some new Mannich bases of Isatin derivatives on corrosion of mild steel in acidic media

Adsorption of four derivatives of piperidinylmethylindoline-2-one on mild steel surface in 1 M HCl solution and its corrosion inhibition properties has been studied by a series of techniques, such as polarization, electrochemical impedance spectroscopy (EIS), weight loss and quantum chemical calculation methods. The values of activation energy (E_a) for mild steel corrosion and various thermodynamic parameters were calculated and discussed. Potentiodynamic polarization measurements showed that all inhibitors are mixed type. The degree of surface coverage was determined by using weight loss measurements and it was found that adsorption process of studied inhibitors on mild steel surface obeys Langmuir adsorption isotherm.     

Nitrotetrazolium blue chloride as a novel corrosion inhibitor of steel in sulfuric acid solution

The inhibition effect of nitrotetrazolium blue chloride (NTBC) on the corrosion of cold rolled steel (CRS) in 0.5 M H₂SO₄ was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The results show that NTBC is a good inhibitor, and the adsorption of NTBC on CRS surface obeys Langmuir adsorption isotherm. Polarization curves show that NTBC acts as a mixed-type inhibitor. EIS spectra consist of large capacitive loop at high frequencies followed by a small inductive one at low frequency values, and charge transfer resistance increases with the inhibitor concentration.     

Caffeic acid as a green corrosion inhibitor for mild steel

The inhibitor effect of the naturally occurring biological molecule caffeic acid on the corrosion of mild steel in 0.1 M H₂SO₄ was investigated by weight loss, potentiodynamic polarization, electrochemical impedance and Raman spectroscopy. The different techniques confirmed the adsorption of caffeic acid onto the mild steel surface and consequently the inhibition of the corrosion process. Caffeic acid acts by decreasing the available cathodic reaction area and modifying the activation energy of the anodic reaction. A mechanism is proposed to explain the inhibitory action of the corrosion inhibitor.     

Corrosion inhibition of mild steel in hydrochloric acid solution by some double Schiff bases

The inhibition effect of four double Schiff bases on the corrosion of mild steel in 2 M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. The inhibitors were adsorbed on the steel surface according to the Langmuir adsorption isotherm model. From the adsorption isotherm, some thermodynamic data for the adsorption process were calculated and discussed. Kinetic parameters activation such as E_a, ΔH∗, ΔS∗ were evaluated from the effect of temperature on corrosion and inhibition processes. Quantum chemical calculations have been performed and several quantum chemical indices were calculated and correlated with the corresponding inhibition efficiencies.     

Experimental and molecular dynamics studies on corrosion inhibition of mild steel by 2-amino-5-phenyl-1,3,4-thiadiazole

The corrosion inhibition of mild steel in 0.5 M H₂SO₄ and 1.0 M HCl by 2-amino-5-phenyl-1,3,4-thiadiazole (APT) has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results show that the inhibition efficiency increases with the increase of APT concentration in both acids, and the higher inhibition efficiency is obtained in 0.5 M H₂SO₄. The adsorption of APT molecules on the steel surface obeys Langmuir adsorption isotherm in both acids, and occurs spontaneously. The molecular dynamics method has also been used to simulate the adsorption of ATP molecule and solvent ions on the iron surface. The results show that with the adsorption of sulfate ions the Fe + anion + APT system has the higher negative interaction energy comparing to the case of the adsorption of chloride ions.     

2,2′-Dithiobis(3-cyano-4,6-dimethylpyridine): A new class of acid corrosion inhibitors for mild steel

The title compound (PyS)₂ has been synthesized and its inhibiting action on the corrosion of mild steel in 1-5 M H₂SO₄ solutions at 35-50 °C has been investigated by polarization resistance (R_p), polarization curves and electrochemical impedance spectroscopy (EIS). (PyS)₂ showed excellent performance and its efficiency did not affect either by increasing the acid concentration or rise of temperature. Polarization curves indicated that (PyS)₂ behaves mainly as anodic inhibitor in 1 M H₂SO₄ solutions and as a mixed-type inhibitor in 3 and 5 M H₂SO₄ solutions at different temperatures. Adsorption of (PyS)₂ on the steel surface followed Temkin’s adsorption isotherm with a very high negative value of the free energy of adsorption . The activation parameters of the corrosion process were calculated. EIS showed that the charge transfer controls the corrosion process in the uninhibited and inhibited solutions.     

Corrosion monitoring of mild steel in sulphuric acid solutions in presence of some thiazole derivatives – Molecular dynamics, chemical and electrochemical studies

The physical behavior of three selected thiazole derivatives, namely 2-Amino-4-(p-tolyl)thiazole (APT), 2-Methoxy-1,3-thiazole (MTT) and Thiazole-4-carboxaldehyde (TCA) at iron (1 1 0) surface dissolved in aqueous solution were studied via molecular dynamics (MD) simulations. From the calculated binding energies, APT showed preferred adsorption on the steel surface among the three tested thiazole derivatives. The inhibition performance of the three thiazoles on the corrosion of mild steel in 0.5 M H₂SO₄ solutions was investigated at 25 °C. Measurements were conducted under various experimental conditions using weight loss, Tafel polarization and electrochemical impedance spectroscopy. Electrochemical frequency modulation (EFM) technique was also employed here to make accurate determination of the corrosion rates and test validation of the Tafel extrapolation method for measuring corrosion rates. Polarization curves showed that the three thiazole derivatives were of mixed-type inhibitors for mild steel corrosion in 0.5 M H₂SO₄ solution. EFM results were in agreement with other traditional chemical and electrochemical techniques used in corrosion rate measurements. Chemical and electrochemical measurements are consistent with computational study that APT is the most effective inhibitor among the tested thiazoles.     

Experimental and theoretical studies of thiazoles as corrosion inhibitors for mild steel in sulphuric acid solution

The inhibition effects of 2-amino-5-mercapto-1,3,4-thiadiazole (2A5MT) and 2-mercaptothiazoline (2MT) on mild steel corrosion in 1.0 M H₂SO₄ were studied with potentiodynamic polarization, linear polarization resistance and electrochemical impedance spectroscopy techniques. It was shown that both 2A5MT and 2MT act as good corrosion inhibitors for mild steel protection. The high inhibition efficiencies were attributed to the simple blocking effect by adsorption of inhibitor molecules on the steel surface. The effects of the presence of extra NH₂ group and N atom in 2A5MT on the ability to act as corrosion inhibitors were investigated by theoretical calculations.     

Bis (benzimidazol-2-yl) disulphide: An efficient water soluble inhibitor for corrosion of mild steel in acid media

The inhibition effect of Bis (benzimidazol-2-yl) disulphide (BIMDS) on corrosion behavior of mild steel (MS) in 1.0 M HCl and 0.5 M H₂SO₄ was studied using different techniques. These studies have shown that studied compound is a good inhibitor for MS in 1.0 M HCl and 0.5 M H₂SO₄ solutions. Inhibitor showed better performance in 0.5 M H₂SO₄ solutions than 1.0 M HCl. Polarization measurements indicated that BIMDS is a mixed-type inhibitor in both acid media. Adsorption of inhibitor molecules on the mild steel surface showed Langmuir isotherm model in both acid media.     

Inhibitor effects of triazole derivatives on corrosion of mild steel in acidic media

Abstract

The inhibitive action of triazoles on the corrosion of mild steel has been studied through weight loss and various electrochemical techniques. Results obtained show that these organic compounds are very good inhibitors. Triazoles are able to reduce the corrosion of steel more effectively in 1M HCl than in 0·5M H₂ SO₄ . Potentiodynamic polarisation studies clearly reveal the type of inhibitor. Changes in impedance parameters (the charge transfer resistance R_t and the double layer capacitance C_dl ) are related to adsorption of triazoles on the metal surface, leading to the formation of a protective film which grows with increasing exposure time. The adsorption of these inhibitors on the mild steel surface in both acids obeys the Langmuir adsorption isotherm. The comparative study of corrosion inhibition of triazole derivatives indicates that the efficiency of the 4-aminotriazole is greater than that of the 4H-triazole.     

Mono- and dicationic benzothiazolic quaternary ammonium bromides as mild steel corrosion inhibitors. Part I: Gravimetric and voltammetric results

Seven quaternary ammonium bromides of different heterocyclic compounds were investigated as corrosion inhibitors of mild steel in 1 M HCl using gravimetric and polarisation techniques. For comparison gravimetric experiments were carried out in 1 M H₂SO₄ as well. The inhibitor efficiency was found to depend on both concentration and molecular structure of the inhibitor. The polarisation curves revealed that the inhibitors were of mixed type. The adsorption of almost all inhibitors was well described by the Frumkin isotherm. The adsorption isotherm parameters were determined. Conformational changes in the molecular structure favour the adsorption and thus increase the inhibitive effect.     

Inhibition by Ginkgo leaves extract of the corrosion of steel in HCl and H2SO4 solutions

The inhibition effect of Ginkgo leaves extract (GLE) on the corrosion of cold rolled steel (CRS) in 1.0–5.0 M HCl and 0.5–2.5 M H₂SO₄ solutions was investigated for the first time by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) methods. The results show that GLE is a good inhibitor, and exhibits more efficient in 1.0 M HCl than 0.5 M H₂SO₄. The adsorption of GLE on CRS surface obeys Langmuir adsorption isotherm. GLE acts as a mixed-type inhibitor in 1.0 M HCl, while a cathodic inhibitor in 0.5 M H₂SO₄.     

Adsorption Properties and Inhibition of Mild Steel Corrosion in 0.5 M H2SO4 Solution by Some Triazol Compound

The effect of 3,5-dimethylbenzoic acid [1,2,4]triazol derivative (DBTE) on the corrosion of mild steel in 0.5 M H₂SO₄ solution was evaluated in this study by means of weight loss test, EIS, potentiodynamic polarization, and SEM. The results revealed that DBTE acted as a mixed-type inhibitor without change of the mechanism of hydrogen evolution. The inhibition efficiency increased with the increase in concentration of DBTE, and the adsorption behavior of DBTE on the mild steel surface followed the Langmuir adsorption isotherm. The thermodynamic parameters reveal that the chemisorption was the dominant adsorption process, and good inhibition performances in the studied range of temperatures were observed.