Inhibiting action of N-phenacylmethylheterylazolium bromides under conditions of acid steel corrosion

Inhibiting action of N-phenacylmethylheterylazolium bromides based on imidazole, benzimidazole, benzthiazole, and their mixtures with potassium iodide, urotropin, or paraform on the steel corrosion in 3 M H₂SO₄ solutions was studied.     

Corrosion-protective properties of 1-phenacylmethyl-2-arylcarbamido(arylthiocarbamido)pyridinium bromides

Inhibiting effect of 1-phenacylmethylpyridinium bromides containing urea or thiourea substituents in the pyridinium ring on steel and zinc corrosion in sulfuric acid solutions was studied.     

1-Phenacylmethyl-2-(acylaminothiocarbonylamino)pyridinium bromides as protectors of steel acid corrosion

Inhibiting effect of 1-phenacylmethylpyridinium bromides containing acylthiourea substituents in the pyridine ring on corrosion of mild steel in sulfuric acid (3 M) was studied.     

Comparative effect of N-decyl- and N-phenacylmethylpyridinium bromides in acid corrosion of steel

Comparative analysis of inhibitory effect of N-decyl and N-phenacylmethylpyridinium bromides and their mixtures with potassium chloride, bromide, and iodide, and also with urotropin and paraform was carried out at corrosion of steel 08 KP in 3 M H₂SO₄ solutions.     

Protective effect of 1-benzyl-2-R-pyridinium halides in steel acid corrosion

The inhibiting effect of 1-benzoyl-2-R-pyridinium halides on the acid corrosion of steel was studied and compared with that of 1-phenacylmethyl-2-R-pyridinium halides.     

Inhibiting effects of benzamide derivatives on the corrosion of mild steel in hydrochloric acid solution

The inhibition effect of new heterocyclic compounds, namely N-(cyanomethyl)benzamide (BENZA) and N-[(1H-tetrazol-5-yl)methyl]benzamide (BENZA-TET), on mild steel corrosion 1 M HCl was investigated using electrochemical measurements. The results indicated that the inhibition efficiency depends on concentration, immersion time and temperature. The BENZA is a better inhibitor than BENZA-TET. Polarization measurements showed that the inhibitor BENZA-TET is a cathodic type, but BENZA acts as a mixed type inhibitor. In addition, the changes in impedance parameters indicated that these compounds adsorbed on the metal surface leading to the formation of a protective film. Adsorption of benzamide derivatives on the mild steel surface was investigated to consider basic information on the interaction between the inhibitors and the metal surface. It was found to obey the Langmuir adsorption isotherm. From the temperature dependence, the activation energy in the presence of (BENZA) was found to be inferior to that in uninhibited medium. In order to explain why BENZA is the most efficient inhibitor, quantum chemical calculations were applied. The relationships between quantum chemical parameters and corrosion inhibition efficiency have been discussed to see if there is any correlation between them.     

Inhibiting effects of 2-mercapto-1-methylimidazole on copper corrosion in 0.5 M sulfuric acid

The inhibiting efficiency of 2-mercapto-1-methylimidazole (MMI) on copper corrosion in sulfuric acid was investigated at 30 °C. Its effectiveness was assessed through electrochemical impedance spectroscopy, potentiodynamic polarization and gravimetric measurements. The results of study reveal that the inhibition efficiency of MMI depends on its concentration and attains approximately 81% at 10^?4 M. The inhibitor was adsorbed on the copper surface according the Langmuir adsorption isotherm model. The value of standard free energy of adsorption was calculated from this isotherm.     

Effect of acetic acid on CO2 corrosion of carbon steel in NaCl solution

Potentiodynamic sweep and electrochemical impedance spectroscopy measurements were applied to investigate the effects of both temperature and acetic acid (HAc) on the anodic and cathodic reactions in CO₂ corrosion of P110 steel in 3.5% NaCl solution. The temperatures were controlled at 30 and 60 °C. The concentrations of HAc were controlled at 0, 1000, 3000 and 5000 ppm. In this work, the corrosion parameters of polarization curves, such as corrosion potential (E_corr), corrosion current density (i_corr), and anodic and cathodic branch slopes (b_a and b_c), are presented and discussed in detail. In addition, the equivalent circuit models and ZsimpWin software were utilized to discuss the Nyquist plots. The plots showed that the E_corr values shifted in the positive direction as the HAc concentration increased. The i_corr values increased with the increase in HAc concentration, indicating that HAc could accelerate the corrosion. The impedance spectra measured at 30 and 60 °C have different time constants and characterization. The coverage fraction θ and the thickness L of corrosion film are two most important controlled variables that influence and control the CO₂ corrosion mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.     

The effect of acetohydroxamic acid on stainless steel corrosion in nitric acid

We present the first study of the effect of acetohydroxamic acid (AHA) on the corrosion behaviour of stainless steels. Particularly, studies have been performed using steels and physico-chemical conditions equivalent to those proposed for use in advanced nuclear reprocessing platforms. In these, AHA has been shown to have little effect on either steel passivation or reductive dissolution of both SS304L and SS316L. However, under transpassive dissolution conditions, AHA while in part electrochemically oxidised to acetic acid and nitroxyl/hydroxylamine, also complexes with Fe^3 +, inhibiting secondary passivation and driving transpassive dissolution of both steels.     

The effect of 2-aminoquinoline-6-carboxylic acid on the corrosion behavior of mild steel in hydrochloric acid

The inhibitive effect of 2-aminoquinoline-6-carboxylic acid (AQC) against mild steel corrosion in 1?M HCl solutions was investigated using conventional weight loss, potentiodynamic polarization, linear polarization and electrochemical impedance spectroscopy methods. The weight loss results showed that AQC is an excellent corrosion inhibitor since its efficiency increased with the concentration to attain 91.8?% at 500?mg?l^?1. Electrochemical polarization measurements revealed that AQC acted as a mixed-type inhibitor and the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the inhibitor is due to the adsorption of the molecule leading to the formation of a protective layer on the surface of mild steel. The adsorption was assumed to occur on the steel surface through the active centers of the molecule. The inhibition action of AQC was discussed in view of Langmuir adsorption isotherm. Density functional theory calculations of quantum parameters were used to explain efficiency in relation with molecular structure.     

AC impedance measurement of cystine adsorption at mild steel/sulfuric acid interface as corrosion inhibitor

Alternating current (AC) impedance measurements of mild steel/sulfuric acid interface in the absence and in the presence of various concentrations of cystine (Cys–Cys) have been carried out in the 100 kHz–10 mHz frequency range. The results revealed that Cys–Cys is a good and effective inhibitor for mild steel corrosion in 0.5 M H₂SO₄ and its percent inhibition efficiency changes with its concentration. Changes in impedance parameters indicated the adsorption of Cys–Cys on the mild steel surface, which was verified by scanning electron microscope (SEM) and atomic force microscope (AFM) photographs. Adsorption of Cys–Cys on mild steel surface was found to obey the Langmuir adsorption isotherm with a standard free energy of adsorption of −33.2 kJ/mol. Energy gaps for the interactions between mild steel surface and Cys–Cys molecule were found to be close to each other showing that Cys–Cys owns capacity to behave as both electron donor and electron acceptor.     

Inhibition of cold rolled steel corrosion in sulphuric acid solution by 2-mercapto-1-methylimidazole: Time and temperature effects treatments

2-Mercapto-1-methylimidazole (MMI) has been evaluated as a corrosion inhibitor for cold rolled steel in aerated 2 M H₂SO₄ by gravimetric method. The effect of MMI on the corrosion rate was determined at various immersions time and concentrations. The effect of the temperature on the corrosion behaviour with addition of different concentrations of MMI was studied in the temperature range 30–60 °C. The MMI acts as an effective corrosion inhibitor for cold rolled in sulphuric acid medium. The inhibition process is attributed to the formation of an adsorbed film of MMI on the metal surface which protects the metal against corrosion. The protection efficiency increased with increase in inhibitor concentration at various immersions time and decreased with increase in temperature. Adsorption of MMI on the cold rolled steel surface is found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined.     

The effect of acetic acid on the pit propagation in CO2 corrosion of carbon steel

The role of acetic acid (HAc) on the pit growth in CO₂ corrosion of carbon steel pipelines is studied by means of an artificial pit electrode. The current flowing between the artificial pit and the outer surface was measured with a zero resistance ammeter. It is shown that the corrosion potential increases with increasing HAc concentration. Depletion of HAc inside the pit imposed a potential difference that triggered the pit growth. The pit did not grow in absence of HAc. The pit growth was self-sustained only to a certain pit depth, beyond which the dissolution current at the bottom of the pit vanished. This is in good agreement with field observations mainly in the case of top-of-line corrosion phenomena.     

Experimental and theoretical investigations of adsorption of fexofenadine at mild steel/hydrochloric acid interface as corrosion inhibitor

The present study examines the effect of fexofenadine, an antihistamine drug, on corrosion inhibition of mild steel in molar hydrochloric acid solution using different techniques under the influence of various experimental conditions. Results revealed that fexofenadine is an effective inhibitor and percent inhibition efficiency increased with its concentration; reaching a maximum value of 97% at a concentration of 3.0 × 10⁻⁴ M. Fourier-transform infrared spectroscopy (FTIR) observations of steel surface confirmed the protective role of the studied drug. Polarization studies showed that fexofenadine is a mixed-type inhibitor. The adsorption of the inhibitor on mild steel surface obeyed the Langmuir adsorption isotherm with free energy of adsorption (∆G°_ads) of −40 kJ mol⁻¹. Energy gaps for the interactions between mild steel surface and fexofenadine molecule were found to be close to each other showing that fexofenadine has the capacity to behave as both electron donor and electron acceptor. The results obtained from the different corrosion evaluation techniques are in good agreement.     

Adenosine as corrosion inhibitor for mild steel in hydrochloric acid solution

Research on Chemical Intermediates - (2R,3R,4S,5R)-2-(6-amino-9H-purin-9-yl)-5-(hydroxymethyl)oxolane-3,4-diol (adenosine) is an identified component present in agarwood leaf extract. The corrosion...     

Allylacetylenes and their derivatives as inhibitors of steel corrosion in sulfuric acid

New functionalized derivatives of allylacetylenes were prepared, and their ability to inhibit corrosion of St.3 low-carbon steel in 5 N sulfuric acid was studied. The effectiveness of inhibition of steel corrosion was studied in relation to the structure of acetylene derivatives, their concentration, and temperature of acidic medium.     

Effect of temperature on CO2 corrosion of carbon steel

This work investigates the effect of temperature on the corrosion product layer of carbon steel exposed to a CO₂‐containing solution. The measurement techniques, such as scanning electron microscopy with energy dispersive spectrometry, X‐ray diffraction, and X‐ray photoelectron spectroscopy, were used to systematically characterize the morphology and composition of the corrosion product layer. The corrosion rates were calculated by weight loss method. The corrosion mechanisms as a function of temperature are studied and discussed. The results showed that temperature is an important factor in the corrosion rate of carbon steel. Copyright © 2009 John Wiley & Sons, Ltd.