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The influence of N‐heterocyclics, viz. imidazole (IA), benzimidazole (BIA) and 2‐methyl imidazole (MIA) on the corrosion and hydrogen permeation through mild steel in 1 N H₂SO₄ and in 1N HC1 has been studied using weight loss and various corrosion monitoring techniques. Imidazole and benzimidazole inhibit the corrosion of mild steel in both the acidic solutions, but methyl imidazole accelerates the corrosion. They behave as cathodic inhibitors by influencing the cathodic polarization reaction. Except methyl imidazole, the other two compounds reduce the hydrogen permeation current in both the acids. The adsorption of these compounds on the mild steel surface from both the acids obeys Temkin’s adsorption isotherm. Trends in the increase of charge transfer resistance and decrease of capacitance values also show the adsorption of inhibitors on the metal surface.

The purpose of this paper is to investigate three Arylfuranylnicotinamidine derivatives against corrosion of carbon steel (C-steel) in 1.0 M HCl by chemical and electrochemical means. The inhibition efficiency (%IE) increases with increasing the dose of inhibitors. The tested compounds exhibited improved performance at elevated temperature, with %IE reaching 93 percent at 21 µM. Tafel polarization method revealed that the tested compounds act as mixed-type inhibitors. The inhibition action was rationalized due to chemical adsorption of inhibition molecules on C-steel surface following Temkin’s isotherm. Surface examination was carried out by AFM and FTIR techniques. Further, theoretical chemical approaches were used to corroborate the experimental findings.

Experimental and computational methods were applied to investigate the efficiency of these new compounds. These studies are complemented with spectral studies and surface morphological scan by AFM. The theoretical results indicate good correlation with experimental findings.

The tested derivatives are promising corrosion inhibitors for C-steel in the acid environment. The molecular scaffold of this class of compounds can be used to design new highly efficient inhibitors by screening its activity by modeling studies.

The studied compounds are safe inhibitors and greatly adsorbed on Fe surface. The action of compounds is enhanced with temperature, which means these compounds can be used in higher temperature systems. The new compounds are effective at very low concentration.

Inhibition of the corrosion of mild steel in 1‐5 N HCl and H₂SO₄ by a macrocyclic compound viz., tetramethyl‐dithia‐octaazacyclotetradeca hexaene (MTAT) was studied as a corrosion inhibitor by weight loss and electrochemical potentiodynamic polarization methods. The influence of temperature, immersion time and acid concentration was also studied in the presence of MTAT in HCl and H₂SO₄. The potentiodynamic polarization carried out in 1‐5 N HCl and H₂SO₄ in the absence and presence of inhibitor revealed that MTAT is a mixed inhibitor. MTAT exhibited better performance as a corrosion inhibitor in H₂SO₄ and its performance was further improved the addition of KI due to synergism. The adsorption of MTAT on the mild steel surface obeyed Temkin adsorption isotherm.

The influence of a newly synthesised organic compound on the inhibition of corrosion of arsenical aluminium brass in a NaCl solution has been investigated using weight loss measurements, potentiodynamic polarization studies and impedance measurements. Different corrosion kinetic parameters obtained from polarisation studies reveal that the inhibition of corrosion of arsenical aluminium brass in NaCl is under mixed control. UV‐reflectance, X‐ray diffraction and scanning electron microscopic studies have also been carried out to understand the mechanism of inhibition of corrosion, and also the morphological changes on the surface of the alloy. The adsorption of this compound on the metal surface from 3.5% NaCl solution is found to obey Temkin’s adsorption isotherm.

The purpose of this paper is to study methyl green dye (MG) as a corrosion inhibitor for low carbon steel (LCS) in hydrochloric acid (1 M) and sulphuric acid (0.5 M) and to assess the effect of temperature variation and halide additives on the inhibition efficiency.

Corrosion rates are monitored using the gravimetric technique. Inhibition efficiency is determined by comparing the corrosion rates in the absence and presence of additives. Attempts are also made to elucidate the inhibition mechanism from the trend of inhibition efficiency with change in temperature and type of acid anion.

MG reduces the corrosion rate of the LCS specimens in both acid media within the investigated temperature range by adsorption at the metal/solution interface. Inhibition efficiency increases with MG concentration but decreases with rise in temperature. Maximum values of 67 and 73 per cent are obtained in 1 M HCl and 0.5 M H₂SO₄, respectively, at [MG]=0.001 mol dm⁻³. Halide additives increase the inhibition efficiency mainly in the sulphuric acid medium.

The inhibiting effect of MG is studied within a fixed concentration range, which can be expanded for further studies. The same applies to the effect of halide additives. Also, the dye structure can be modified by introducing different functional groups, and the effect on inhibition efficiency is investigated.

The research findings can find practical application for corrosion control in aqueous acidic environments.

This paper provides new information on the application of MG for corrosion inhibiting purposes. The experimental results form part of an extensive database on the corrosion inhibiting characteristics of organic dyes.

A variety of bisquaternary ammonium salts was prepared for the first time by reacting N,N,N′,N′‐tetraallyl‐1,6‐hexanediamine with allyl chloride, propargyl chloride, benzyl chloride, and 1‐bromododecane in excellent yields (>90 per cent). Inhibition efficiency for different concentrations of the synthesised compounds for the inhibition of corrosion of carbon steel in 1 M HCl exposed for 6 h at 60°C was determined gravimetrically. The bisquaternary salts exhibited excellent inhibition efficiencies (97‐99 per cent) in the acidic solution containing 400 ppm of the inhibitor. Comparable results were obtained by the electrochemical method using Tafel plots for the inhibition efficiency of the synthesised compounds. The adsorption of these compounds on carbon steel surface was found to obey Temkin's adsorption isotherm. The work marked the beginning of constituting an important class of new inhibitors containing multiple adsorption centres of positive nitrogens as well as π‐donor moieties.

The purpose of this paper is to evaluate the corrosion inhibition potential of Calotropis procera in sulphuric acid medium on mild steel with a view to developing green corrosion inhibitors.

Extract of the C. procera was studied for its corrosion inhibitive effect by weight loss, electrochemical, SEM and UV methods. Using weight loss measurement data, mechanism of inhibitive action is probed by fitting in adsorption isotherm.

C. procera has been found to show significant corrosion inhibitive effect in sulphuric acid medium on mild steel. Inhibition is through adsorption of the phytoconstituents on mild steel following Tempkin adsorption isotherm. The results of ac impedance and polarization studies correlate well with the weight loss studies.

The plant has been investigated for the first time for its corrosion inhibitive effect. The effect has been studied by proven methods. This green inhibitor can find use in the inhibition of corrosion in industries where mild steel is used as a material of choice for the fabrication of machinery.

The aim is to demonstrate corrosion inhibition capabilities of several isoxazolidines, containing hydrophobic substituents and having varying degree of steric congestion around nitrogen.

A number of isoxazolidines were prepared. Corrosion inhibition efficiencies of these organic compounds were determined by gravimetric and electrochemical methods, using carbon steel as the substrate metal and 0.5 M H₂SO₄ at 40‐70°C as the corrosive environment. Concentration of inhibitor was varied between 5 and 400 ppm.

Increase in steric congestion around the nitrogen centre and hydrophobic chain lengths as well as increase in temperature (in the presence of the inhibitor in the higher concentration range 100‐400 ppm) were found to increase the corrosion inhibition efficiency of the isoxazolidines. Electrochemical measurements corroborated these results. Thermodynamic parameters (ΔG_ads⁰,ΔH_ads⁰,ΔS_ads⁰) for the adsorption process and kinetic parameters for the metal dissolution (or hydrogen evolution) reaction were determined.

This is the first time the corrosion inhibition characteristics of isoxazolidines, an important class of readily accessible compounds, have been evaluated in H₂SO₄ medium.

This paper mainly aims to study the influence of some thiosemicarbazides, namely, 1‐hydroxyphenyl‐4‐phenyl thiosemicarbazide (HPT), 1,4‐diphenyl thiosemicarbazide (DPT), 1‐aminophenyl‐4‐phenyl thiosemicarbazide (APT) and 1‐cinnamyl‐4‐phenyl thiosemicarbazide (CPT) on the corrosion inhibition of carbon steel in hydrochloric and sulphuric acid.

All inhibition experiments were conducted on carbon steel in 1N HCl and 1N H₂SO₄ solution. Weight loss experiments were carried out according to the ASTM standard procedure. Polarization studies were carried out in a three‐electrode cell assembly connected to an EG&G Princeton applied research potentiostat/galvanostat (model 173).

For all the compounds a consistent trend of increase in inhibition efficiency was observed as a function of inhibitor concentration. The adsorption of all the compounds on to the carbon steel surface in the acidic solution was found to obey the Tempkin's adsorption isotherm. The values of activation energy and free energy of adsorption for all the compounds were also calculated. Polarization measurement revealed that the studied thiosemicarbazides act predominantly as mixed inhibitors in both the acid solutions, with the exception of DPT, which predominantly behaved as a cathodic inhibitor in 1N HCl.

These inhibitors could have application in industries, where hydrochloric and sulphuric acid solution are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary.

This paper reveals that thiosemicarbazides can be successfully used for protection of carbon steel corrosion in acid solutions.

A few nitrones such as N‐benzilidene aniline‐N‐oxide, N‐(O‐hydroxy benzilidene) aniline‐N‐oxide (HN) and N‐(α‐naphthylidene) aniline‐N‐oxide (NN) have been synthesised and investigated for evaluating their efficiency as inhibitors for the corrosion of mild steel in 1M HCl at different concentrations of nitrones ranging from 0.025‐1.0mM and at different temperatures ranging from 30‐70°C. Among these compounds NN gives the best performance even at higher temperatures. Potentiodynamic polarisation studies reveal the fact that all compounds behave as mixed type inhibitors. Hydrogen permeation studies reveal the fact that all the compounds bring down the permeation current. The absorption of these compounds on the mild steel surface from 1M HCl obeys Temkin’s absorption isotherm.