Corrosion Of Steel In Acid Medium Research Articles

2-Acetylpyridine-N(4)-Morpholine Thiosemicarbazone (HAcpMTSc) as a Corrosion Inhibitor on Mild Steel in HCl

2-Acetylpyridine-N(4)-morpholine thiosemicarbazone (HAcpMTSc) was synthesized and investigated as an inhibitor for mild steel corrosion in acid media. Various concentrations of the inhibitor in 1 M HCl solution were tested, and the corrosion inhibition efficiency to mild steel was estimated by means of weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. The adsorption equilibrium constant (Kads) and standard free energy of adsorption (ΔG°ads) were calculated. The nature of inhibition was studied by various spectroscopic techniques such as UV–visible, FTIR, and EPR spectroscopies and by using surface analysis methods (i.e., SEM-EDS).

Inhibition of mild steel corrosion in acidic medium using starch and surfactants additives

AbstractThe corrosion inhibition of mild steel in 0.1M H2SO4 in presence of starch (polysaccharide) was studied using weight loss and potentiodynamic polarization measurements in the temperature range of 30–60°C. Starch inhibits the corrosion rates of mild steel to a considerable extent; the maximum inhibition efficiency (%IE) being 66.21% at 30oC in presence of starch concentration of 200 ppm. The effect of the addition of very small concentration of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide on the corrosion inhibition behavior of starch was also studied. The IE of starch significantly improved in presence of both the surfactants. The effect of surfactants on the corrosion inhibition behavior of starch appears to be synergistic in nature. Starch alone and in combination with surfactants is found to obey Langmuir adsorption isotherm from the fit of the experimental data of all concentration and temperature studied. Phenomenon of physical adsorption is proposed from the trend of IE with temperature and also the values Ea, ΔGads, and Qads obtained. The results obtained by potentiodynamic polarization measurements are consistent with the results of the weight loss measurement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Inhibition Efficiency of Alkaline Metal Salts on Carbon Steel Corrosion in Acidic Media

not Available.

Inhibitive Properties, Thermodynamic Characterization and Quantum Chemical Studies of Secnidazole on Mild Steel Corrosion in Acidic Medium

Inhibitive Properties, Thermodynamic Characterization and Quantum Chemical Studies of Secnidazole on Mild Steel Corrosion in Acidic Medium

Dianiline Schiff Bases as Inhibitors of Mild Steel Corrosion in Acid Media

Dianiline Schiff Bases as Inhibitors of Mild Steel Corrosion in Acid Media

Synergistic Effect of Different Salts on the Inhibition Efficiency of a Cationic Surfactant on Steel Corrosion in Acid Medium

Corrosion inhibition effect of cationic surfactant DTAB (Dodecyl Threemethyl Ammonium Bromide) on low carbon steel in 1M HCl was studied using weight loss and OCP (Open Circuit Potential) methods. Inhibition efficiency increases with increasing of surfactant concentration. Also synergistic effect between surfactant and different alkaline metals salts (KCl, NaCl, NaBr, NaI, LiCl, Na2SO4, and NaNO3) in 1 M HCl is investigated. The effect of different anions and different metal cations on inhibition efficiency is discussed. The inhibition efficiency increases with increasing of salts concentration and reaches the maximum value near 0.1 M. The results show that the synergistic effects of salts are in this order Na2SO4 >NaI > LiCl > NaCl > KCl > NaBr > NaNO3. This inhibitor system containing cationic surfactant and an alkaline metal salt is efficient and low-cast for steel corrosion inhibition in HCl medium, even when the concentration of DTAB is as low as 0.5 × 10-4 M.

The Efficiency of Corrosion Inhibitor as Given by Electrochemical Impedance Spectroscopy Tafel Polarization and Weight-Loss Measurements

ABSTRACT The compound 6-methylquinoxalin-2(1H)-one (Q-CH3) was synthesized, and its inhibiting action on the corrosion of mild steel in 1M HCl was investigated by various corrosion-monitoring techniques: electrochemical and weight-loss measurements. Results showed that this compound has fairly good inhibiting properties for steel corrosion in acidic medium, with efficiencies of around 97% at a concentration of 10−2 M. The protection efficiency of this inhibitor decreases slightly with the rise of temperature, and it is improved with the immersion time.

Synergistic Effect of Different Salts on the Inhibition Efficiency of a Cationic Surfactant on Steel Corrosion in Acid Medium

not Available.

N′-[4-(diethylamino)benzylidine]-3-{[8-(trifluoromethyl) quinolin-4-yl]thio}propano hydrazide) as an effective inhibitor of mild steel corrosion in acid media

N′-[4-(diethylamino)benzylidine]-3-{[8-(trifluoromethyl)quinolin-4-yl]thio}propano hydrazide (DEQTPH) was newly synthesized, characterized and tested as a corrosion inhibitor for mild steel in HCl (1 M, 2 M) and H 2SO 4 (0.5 M, 1 M) solutions using weight loss method, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization method. The corrosion inhibition efficiencies measured by all the above three techniques were in good agreement with each other. The mild steel samples were also analyzed by scanning electron microscopy (SEM). The results showed that DEQTPH is an excellent inhibitor for mild steel in acid media. The inhibition efficiency in different acid media was found to be in the order, 0.5 M H 2SO 4 > 1.0 M HCl > 2.0 M HCl > 1.0 M H 2SO 4. The inhibition was assumed to occur via adsorption of the inhibitor molecule on the metal surface. It acts as an anodic inhibitor. In the 30–60 °C temperature range, the DEQTPH adsorption follows Langmuir isotherm model. The protection efficiency increased with increasing inhibitor concentration in the range 0.2 × 10 −4 to 10.5 × 10 −4 M and slightly increased with increasing temperature. Thermodynamic characteristics were discussed. Chemisorption mechanism is proposed.

The inhibition of mild steel corrosion in acidic medium by 1-methyl-3-pyridin-2-yl-thiourea

The effect of 1-methyl-3-pyridin-2-yl-thiourea on the corrosion resistance of mild steel in H 2SO 4 solution was investigated by different techniques. The results show that the inhibition efficiency increases with the increase of inhibitor concentration. This compound affects both the anodic dissolution of steel and the hydrogen evolution reaction in 0.5 M H 2SO 4. The adsorption of this inhibitor is also found to obey the Langmuir adsorption isotherm. From the adsorption isotherm, value of the Δ G ads for the adsorption process was calculated. From the corrosion rate obtained at 25–45 ± 1 °C E a, Δ H a and possible mechanism have been proposed.

Inhibition of aluminium and mild steel corrosion in acidic medium using Gum Arabic

The corrosion behaviour of mild steel and aluminium exposed to H2SO4 solution and their inhibition in H2SO4 containing 0.1–0.5 g/L Gum Arabic (GA) used as inhibitor was studied at temperature range of 30–60 °C using weight loss and thermometric techniques. Corrosion rate increased both in the absence and presence of inhibitor with increase in temperature. Corrosion rate was also found to decrease in the presence of inhibitor compared to the free acid solution. Inhibition efficiency increases with increase in concentration of the inhibitor reaching a maximum of 37.88% at 60 °C for mild steel and 79.69% at 30 °C for aluminium at 0.5 g/L concentration of GA. The inhibitor, GA was found to obey Temkin and El-Awady et al. thermodynamic kinetic adsorption isotherm for mild steel and aluminium respectively from the fit of the experimental data at all concentrations and temperatures studied. The phenomenon of chemical adsorption is proposed for mild steel corrosion, while physical adsorption mechanism is proposed for aluminium corrosion. Results obtained for the kinetic/thermodynamic studies indicate that the adsorption of GA onto the metals surface was spontaneous. GA is a better corrosion inhibitor for aluminium than for mild steel.

Inhibition of mild steel corrosion in acidic medium using synthetic and naturally occurring polymers and synergistic halide additives

The corrosion inhibition of mild steel in H 2SO 4 in the presence of gum arabic (GA) (naturally occurring polymer) and polyethylene glycol (PEG) (synthetic polymer) was studied using weight loss, hydrogen evolution and thermometric methods at 30–60 °C. PEG was found to be a better inhibitor for mild steel corrosion in acidic medium than GA. The effect of addition of halides (KCl, KBr and KI) was also studied. Results obtained showed that inhibition efficiency ( I%) increased with increase in GA and PEG concentration, addition of halides and with increase in temperature. Increase in inhibition efficiency ( I%) and degree of surface coverage ( θ) was found to follow the trend Cl − < Br − < I − which indicates that the radii and electronegativity of the halide ions play a significant role in the adsorption process. GA and PEG alone and in combination with halides were found to obey Temkin adsorption isotherm. Phenomenon of chemical adsorption is proposed from the trend of inhibition efficiency with temperature and values Δ G ads 0 obtained. The synergism parameter, S I evaluated is found to be greater than unity indicating that the enhanced inhibition efficiency caused by the addition of halides is only due to synergism.

Some new triazole derivatives as inhibitors for mild steel corrosion in acidic medium

Two triazole derivatives, 3,4-dichloro-acetophenone-O-1'-(1',3',4'-triazolyl)-methaneoxime (4-DTM) and 2,5-dichloro-acetophenone-O-1'-(1',3',4'-triazolyl)-methaneoxime (5-DTM) were synthesized, and the inhibition effects for mild steel in 1 M HCl solutions were investigated by weight loss measurements, electrochemical tests and scanning electronic microscopy (SEM). The weight loss measurements showed that these compounds have excellent inhibiting effect at a concentration of 1.0 x 10(-3) M. The potentiodynamic polarization experiment revealed that the triazole derivatives are inhibitors of mixed-type and electrochemical impedance spectroscopy (EIS) confirmed that changes in the impedance parameters (R-ct and C-dl) are due to surface adsorption. The inhibition efficiencies obtained from weight loss measurements and electrochemical tests were in good agreement. Adsorption followed the Langmuir isotherm with negative values of the free energy of adsorption Delta G(ads)(o). The thermodynamic parameters of adsorption were determined and are discussed. Results show that both 4-DTM and 5-DTM are good inhibitors for mild steel in acid media.

Experimental and theoretical investigation of the adsorption behaviour of new triazole derivatives as inhibitors for mild steel corrosion in acid media

Three triazole derivatives (4-chloro-acetophenone-O-1′-(1′,3′,4′-triazolyl)-metheneoxime (CATM), 4-methoxyl-acetophenone-O-1′-(1′,3′,4′-triazolyl)-metheneoxime (MATM) and 4-fluoro-acetophenone-O-1′-(1′,3′,4′-triazolyl)-metheneoxime (FATM)) have been synthesized as new inhibitors for the corrosion of mild steel in acid media. The inhibition efficiencies of these inhibitors were evaluated by means of weight loss and electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and polarization curves. Then the surface morphology was studied by scanning electron microscopy (SEM). The adsorption of triazole derivatives is found to obey Langmuir adsorption isotherm, and the thermodynamic parameters were determined and discussed. The relationship between molecular structure of these compounds and their inhibition efficiency has been investigated by ab initio quantum chemical calculations. The electronic properties such as the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energy levels, energy gap (LUMO–HOMO), dipole moment and molecular orbital densities were computed.

Temperature effect on mild steel corrosion in acid media in presence of azoles

The inhibiting properties of four azoles (indole, benzimidazole, benzotriazole, benzothiazole) were investigated in case of mild steel corrosion in 1 M HCl. The effect of temperature was followed. Impedance spectroscopy, polarization resistance, gravimetric and polarization curves methods were applied. An adequate structural model of the interface in inhibitors presence is offered and the values of the corresponding parameters are calculated. The apparent activation energy of the process taking place in an inhibitor presence was determined on the ground of five temperature values in the range from 20 °C to 60 °C using the data obtained by two independent methods. Comparative investigations were carried out in 1 M H 2SO 4 aiming to elucidate the effect of the acid’s anion. The generalization of the data obtained provided to make conclusions concerning the mechanism of the inhibitors’ adsorption.

Investigation on some Schiff bases as corrosion inhibitors for mild steel

In the present work, the effect of some newly synthesized Schiff bases containing sulphur nitrogen as heteroatom was investigated on mild steel corrosion in acidic media. Electrochemical studies of the mild steel samples were performed in an aerated solution of 0.1 M HCl + dimethyl sulphoxide (DMS) as co-solvent. DMS is also behaving as a corrosion inhibitor for mild steel. At low inhibitor concentration and short immersion time one can see only the inhibitive effect of DMS as anodic inhibitor for mild steel. At high concentration and long immersion time inhibition efficiencies are increased and cathodic inhibition is observed.

Evaluation of impedance measurements on mild steel corrosion in acid media in the presence of heterocyclic compounds

Five heterocyclic compounds, having a five atom ring, fused with the benzene ring (indole, benzimidazole, benzotriazole, benzothiazole and benzothiadiazole) were investigated as corrosion inhibitors of mild steel in 1 N HCl using impedance and polarisation resistance methods. Four of these compounds exhibit inhibition properties, while one of them, benzothiadiazole, stimulates the corrosion process. Adequate structure models of the interface are offered. The experimental data show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. At high inhibitor concentrations a second time constant is observed in the impedance spectra. The values of the polarisation resistance determined by the polarisation resistance method are well correlated with the sum of the separate resistances from the impedance measurements.

The inhibition of mild steel corrosion in acidic medium by 2,2′-bis(benzimidazole)

A new corrosion inhibitor, namely 2,2′-bis(benzimidazole) has been synthesised and its inhibiting action on the corrosion of mild steel in acidic bath (1 M HCl) has been investigated by various corrosion monitoring techniques, such as corrosion weight loss test and potentiodynamic polarisation. The results of the investigation show that this compounds have fairly good inhibiting properties for steel corrosion in hydrochloric acid, and is a mixed inhibitor in (1 M HCl). The adsorption of this inhibitor is also found to obey the Langmuir adsorption isotherm.

Experimental and theoretical study of 1-(2-ethylamino)-2-methylimidazoline as an inhibitor of carbon steel corrosion in acid media

The electrochemical behavior of 1-(2-ethylamino)-2-methylimidazoline (imidazoline), its precursor N-[3-(2-amino-ethylamino-ethyl)]-acetamide (amide) and its derivative 1-(2-ethylamino)-2-methylimidazolidine (imidazolidine), is evaluated by using potentiodynamic polarization curves and electrochemical impedance spectroscopy, EIS, techniques in deaerated acid media to compare their corrosion inhibition efficiency. The experimental results suggest that imidazoline is a good corrosion inhibitor at different concentrations whereas amide shows low efficiency values; however, the properties of a corrosion inhibitor were not found in imidazolidine. The reactivity of these compounds was analyzed through theoretical calculations based on density functional theory (DFT) to explain the different efficiencies of these compounds as corrosion inhibitors both in the neutral and protonated form. The theoretical results indicate that imidazoline is the more efficient corrosion inhibitor because of its two very active sites (two nitrogen atoms) and the plane geometry of the heterocyclic ring, thus promoting coordination with the metal surface.

AC and DC study of the temperature effect on mild steel corrosion in acid media in the presence of benzimidazole derivatives

The effect of benzimidazole derivatives on mild steel corrosion in 1 M HCl at five different temperatures has been studied. Impedance, polarization resistance, polarization curves measurement and gravimetric methods have been used. The inhibiting efficiency and the apparent activation energy ( E a) have been calculated in the presence and in the absence of the organic inhibitors. The comparative investigations carried out in 1 M H 2SO 4 and 1 M H 2SO 4+1×10 −4 M KI verify the assumption that the halogen ions facilitate the inhibitors adsorption. The electrostatic absorption of the compound cation form seems more probable. The behaviour of 2-mercaptobenzimidazole (2-SH-BI) contrasts that of the rest of the substances investigated. Chemisorptive adsorption is more probable in this case. The lower value of activation energy E a in the presence of 1-benzyl-benzimidazole when compared to that in 1 M HCl is explained with a partial compensation effect.