Corrosion and hydrogen permeation inhibition for mild steel in HCl by isomers of organic compounds

Abstract

Hydrogen permeation and corrosion inhibition characteristics of isomers of phenylenediamine, toluidine, and nitroaniline were studied on mild steel in 1M HCl. The Tafel extrapolation method was used to determine the inhibition efficiency, while the Devanathan–Stachurski technique was used to determine the hydrogen permeation rate. The adsorption of these compounds on mild steel from 1M HCl obeys Langmuir's adsorption isotherm for toluidine and nitroaniline and Temkin's adsorption isotherm for phenylenediamine. Inhibition efficiency was found to be more for isomers of phenylenediamine followed by those of nitroaniline and toluidine. All the isomers of these three organic compounds inhibit the corrosion of and hydrogen permeation through mild steel in HCl in the order ortho > meta > para for phenylenediamine and nitroaniline and meta > ortho > para for toluidine.     

Some Schiff base compounds as inhibitors for corrosion of carbon steel in acidic media

The corrosion behavior of carbon steel in 0.5 M HCl solution in the absence and presence of new five Schiff bases of indole derivatives was investigated using electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) and potentiodynamic polarization techniques. All the experimental results show that these Schiff bases have excellent corrosion inhibition performance. The polarization curves show that these compounds act as mixed type inhibitors. The adsorption of these Schiff bases on carbon steel surface is consistent with Langmuir adsorption isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds were also studied. Some thermodynamic functions were computed and discussed. The results obtained by the three different electrochemical techniques were in good agreement.     

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.     

Thioamidines as novel class of corrosion inhibitors

Abstract

Four nitrogen substituted thiobisformamidines – phenyl thiobisformamidines (PTBF), tolyl thiobisformamidines (TTBF), anisidyl thiobisformamidines (ATBF), and 4-chlorophenyl thiobisformamidines (CPTBF) – were synthesised and their corrosion inhibiting behaviour for mild steel in 1M, 3M, and 5M HCl was studied. The optimum concentration of these compounds for maximum inhibition efficiency was determined by weight loss methods. All the investigated thiobisformamidines gave more than 95% inhibition in the presence of 1M HCl, and CPTBF showed the best inhibition efficiency (98% in 5M HCl). Potentiodynamic polarisation studies revealed that all the tested compounds are of mixed inhibitor type. The adsorption of these compounds from the acid solution obeyed Temkin's adsorption isotherm. All the inhibitors were able to reduce hydrogen permeation through the steel surface and their performance was enhanced by the addition of iodide ions. Electron impedance spectroscopic studies were also carried out in order to understand the mechanism of inhibition. Auger electron spectroscopic analysis confirmed that the adsorption of these compounds on the surface of the mild steel occurs through nitrogen and sulphur atoms.     

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.     

Corrosion inhibition of mild steel in hydrochloric acid solution by Schiff base furoin thiosemicarbazone

A heterocyclic Schiff base furoin thiosemicarbazone was tested for its corrosion inhibition towards mild steel in 1 M HCl solution using weight loss, Tafel polarization and electrochemical impedance spectroscopy techniques. Furoin thiosemicarbazone revealed good corrosion inhibition efficiency even at low concentrations towards mild steel in HCl medium. Comparison of corrosion inhibition efficiency of Schiff base and its parent amine and effect of temperature on inhibition efficiency were also investigated. The adsorption of furoin thiosemicarbazone on mild steel surface obeys Langmuir isotherm.     

Corrosion inhibition of austenitic stainless steel by some pyrimidine compounds in hydrochloric acid

The inhibition effect of two pyrimidine derivatives on the corrosion of austenitic stainless steel in 1 M HCl has been studied by Tafel plot, linear polarization, and electrochemical impedance spectroscopy (EIS) at 298 K. Results showed that compounds inhibited steel corrosion in a 1 M HCl solution and inhibition efficiencies increased with the concentration of inhibitor. Polarization curves indicated that all studied pyrimidine derivatives act as mixed type (cathodic/anodic) inhibitors. The adsorption of the inhibitors on the stainless steel surface was found to obey the Langmuir and Dubinin–Radushkevich adsorption isotherm models. Negative values of ΔG_ads in the acidic media ensured the spontaneity of the adsorption process.     

Investigation of some Schiff base compounds containing disulfide bond as HCl corrosion inhibitors for mild steel

The inhibition performance of three Schiff bases containing disulfide bond as corrosion inhibitors for mild steel in 2.0 M HCl has been investigated by weight loss measurements, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization study showed that all the inhibitors are mixed type. The adsorption of inhibitors on mild steel surface was found to follow Langmuir adsorption isotherm and the adsorption isotherm parameters (K_ads, ΔG_ads) were determined. Quantum chemical calculations were further applied to reveal the adsorption structure and explain the experimental results. Some samples of mild steel were examined by SEM.     

Synthesis of some aromatic nitro compounds and its applications as inhibitors for corrosion of carbon steel in hydrochloric acid solution

The inhibition effect of some synthetic aromatic nitro compounds on the corrosion of carbon steel in 1 M HCl solution was studied using galvanostatic and potentiodynamic anodic polarization measurements. The percentage inhibition efficiency was found to increase with increasing the concentration of inhibitors and decreasing of temperature. Polarization data indicated that the additives acted as mixed-type inhibitors meaning that these compounds reduced the anodic dissolution of carbon steel and retard the cathodic hydrogen evolution reaction. Inhibition was interpreted in view of formation of insoluble complex adsorbed on the metal surface. The formation of complex was confirmed by UV-spectra. The adsorption of these compounds was found to obey Langmuir adsorption isotherm. Activation energy and some activated thermodynamic parameters were computed and discussed. It was found that these additives provide good protection to carbon steel against pitting corrosion in chloride-containing solution.     

Two pyrazine derivatives as inhibitors of the cold rolled steel corrosion in hydrochloric acid solution

The inhibition effect of two pyrazine derivatives of 2-aminopyrazine (AP) and 2-amino-5-bromopyrazine (ABP) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) was studied by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. The results show that both AP and ABP are good inhibitors, and inhibition efficiency follows the order: ABP > AP. The adsorption of each inhibitor on CRS surface obeys Langmuir adsorption isotherm. Potentiodynamic polarization curves show that two pyrazine derivatives act as mixed-type inhibitors. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability.     

Corrosion inhibition of mild steel by the new class of inhibitors [2,5-bis(n-pyridyl)-1,3,4-thiadiazoles] in acidic media

The inhibitor effect of 2,5-bis(n-pyridyl)-1,3,4-thiadiazoles (n-PTH) on the corrosion of mild steel in 1 M HCl and 0.5 M H₂SO₄ have been investigated using weight loss and electrochemical impedance spectroscopy. Results obtained reveal that these compounds are mixed-type inhibitors and behave better in 1 M HCl than in 0.5 M H₂SO₄. The adsorption of n-PTH on the mild steel surface in both acidic media follows a Langmuir isotherm model.     

Corrosion Inhibition of Carbon Steel in 1 M Hydrochloric Acid using Some Pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]Pyrimidnone Derivatives

The inhibiting effect of three compounds of pyrazolo[3,4-d] pyrimidnone derivatives toward the corrosion of carbon steel in 1.0M HCl solution was investigated using galvanostatic and potentiodynamic anodic polarization techniques. The rise of the concentration of the inhibitors and decreasing the temperature led to the greater of inhibition efficiency. The inhibiting action of these compounds was explicated on the footing of its adsorption on the carbon steel surface. The adsorption operation of these compounds was obeyed Langmuir isotherm. There is only one anodic peak during the anodic cyclic voltammogram This peak was elucidated due to the active dissolution of Fe as Fe²⁺. The percentage inhibition efficiency was computed from the values of peak current density.There is a good convention between the values of the percentage inhibition efficiency gained from the diverse techniques.These compounds inhibit the pitting corrosion of carbon steel by shifiting the pitting corrosion potential to more noble direction. The effect of elevation of temperature on the rate of corrosion in devoid of and containing these compounds was studied and some activated thermodynamic parameters were computed.     

Experimental and theoretical evaluation of semicarbazones and thiosemicarbazones as organic corrosion inhibitors

The inhibition ability of four thiosemicarbazones (1A–D) and two semicarbazones (2A–B) towards carbon steel corrosion in 1.0 M HCl was evaluated by molecular modeling, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) at different inhibitor concentrations. Polarization curves showed that all of the evaluated compounds acted as mixed inhibitors. EIS plots indicated that the presence of the inhibitors increases the charge transfer resistance of the corrosion process, increasing the inhibition efficiency. The adsorption of the evaluated inhibitors obeys the Langmuir adsorption isotherm. The theoretical results were corroborated by experimental data, with both the experimental and theoretical data showing that the thiosemicarbazones are better corrosion inhibitors than the semicarbazones.     

The effect of some bis-thiadiazole derivatives on the corrosion of mild steel in hydrochloric acid

The inhibition effect of bis-thiadiazole derivatives (BTDs) against the corrosion of mild steel in 1 M HCl solution was studied by weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. All the BTDs exhibited >90% inhibition efficiency at concentration as low as 40 ppm. The adsorption of BTDs obeyed Langmuir adsorption isotherm. Both thermodynamic and activation parameters were calculated and discussed. Polarization curves indicate that they are mixed type of inhibitors. All the BTDs were adsorbed physically at lower concentration where as chemisorption was favoured at higher concentration.     

Inhibition effects of some Schiff’s bases on the corrosion of mild steel in hydrochloric acid solution

The corrosion inhibition effect of 4-{[(1Z)-(2-chloroquinolin-3-yl)methylene]amino} phenol (CAP), N-[(1Z)-(2-chloroquinolin-yl)methylene]-N-(4-methoxyphenyl)amine (CMPA) and N-[(1E)-(2-chloroquinolin-3-yl)methylene]-N-(4-nitrophenyl)amine (CNPA) on mild steel in 1.0 M HCl has been investigated using mass loss, polarization and electrochemical impedance techniques at 300 K. The inhibition efficiencies increased with increase in inhibitors concentration. Polarization studies showed that the inhibitors are of predominantly cathodic character. Among the three compounds studied, CAP exhibited the best performance giving more than 97% IE. Some samples of mild steel were examined by SEM. All the inhibitors were found to adsorb on the mild steel surface according to the Langmuir adsorption isotherm.     

Thermodynamic, electrochemical and quantum chemical investigation of some Schiff bases as corrosion inhibitors for mild steel in hydrochloric acid solutions

The corrosion inhibition of mild steel in 1.0 M HCl solution by four Schiff bases was investigated using weight loss and electrochemical measurements and quantum chemical calculations. All compounds showed >90% inhibition efficiency at their optimum concentrations. The activation energy (E_a) of corrosion and other thermodynamic parameters were calculated to elaborate the mechanism of corrosion inhibition. The adsorption of the inhibitors on the mild steel surface follows Langmuir isotherm model. Polarization studies indicated that all studied inhibitors are mixed type. The computed quantum chemical properties viz., electron affinity (EA) and molecular band gap (ΔE_MBG) show good correlation with experimental inhibition efficiencies.     

Three pyrazine derivatives as corrosion inhibitors for steel in 1.0 M H2SO4 solution

The inhibition effect of three pyrazine derivatives of 2-methylpyrazine (MP), 2-aminopyrazine (AP) and 2-amino-5-bromopyrazine (ABP) on the corrosion of cold rolled steel (CRS) in 1.0 M H₂SO₄ solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The results show that all pyrazine compounds are good inhibitors, and inhibition efficiency follows the order: ABP > AP > MP. The adsorption of each inhibitor on CRS surface obeys Langmuir adsorption isotherm. For all these pyrazine derivatives, they act as mixed-type inhibitors. The probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

Influence of 2,3-Dihydroxyflavanone on Corrosion Inhibition of Mild Steel in Acidic Medium

The inhibition effect of 2,3-dihydroxyflavone on the corrosion of mild steel in 100-600 ppm aqueous hydrochloric acid solution has been investigated by weight loss and electrochemical impedance spectroscopy. The corrosion inhibition efficiency increases with increasing concentration and time. The effect of temperature on the corrosion behavior of mild steel in 1 M HCl with addition of inhibitor was studied at the temperature range of 300-330 K. UV-Vis, FTIR, and surface analysis (SEM) was also carried out to establish the corrosion inhibitive property of this inhibitor in HCl solution. The adsorption of this inhibitor on the mild steel surface obeys the Langmuir adsorption isotherm. Electrochemical studies reveal that the inhibitor is a cathodic type.     

An investigation of benzimidazole derivative as corrosion inhibitor for mild steel in different concentration HCl solutions

The influences of a benzimidazole derivative, namely 1,8-bis (1-chlorobenzyl-benzimidazolyl) -octane (CBO) on the corrosion behaviour of mild steel in different concentration HCl solutions were studied by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements and SEM observations. The results showed that CBO acted as an excellent and a mixed-type inhibitor via strongly chemical adsorption onto mild steel surface to suppress simultaneously both anodic and cathodic processes according to the Langmuir adsorption isotherm. Inhibition efficiencies increased with increasing concentration of inhibitor and HCl. An inhibition mechanism was proposed in terms of strongly adsorption of inhibitor molecules on mild steel surface.     

Corrosion inhibition of carbon steel in hydrochloric acid solution by fruit peel aqueous extracts

The inhibitive action of the aqueous extracts of fruit peels against corrosion of carbon steel in a 1 M HCl solution was investigated using electrochemical impedance spectroscopy, potentiodynamic polarization curves, weight loss measurements and surface analysis. We analyzed aqueous extracts of mango, orange, passion fruit and cashew peels in different concentrations and found that the extracts act as good corrosion inhibitors for the tested system. The inhibition efficiency increases with increasing extract concentration and decreases with temperature. The adsorption of components of the fruit peel extracts on the surface of the carbon steel follows the Langmuir adsorption isotherm.