Corrosion behaviour of steel rebar: effect of simulated concrete pore solution and chloride ions

In this work, we investigate the corrosion behavior of steel rebar (SR) in four simulated concrete pore solutions (CPS): NaOH+KOH (CPS1), Na2CO3 (CPS2), NaOH (CPS3) and Ca(OH)2 (CPS4) medium.  Effect of addition of Cl- anions as pollutant on pitting and uniform corrosion of SR is investigated by using potentiodynamic polarization (PDP) technic. The result obtained show that uniform and pitting corrosion of SR are strongly influenced by the nature of simulated CPS. In unpolluted CPS’s, only uniform corrosion of SR is observed in all cases. SR has excellent corrosion resistance in CPS4 compared to the other simulated CPS. In the polluted CPS’s by Cl- anions, we observe an accelerated uniform corrosion especially in CPS1, CPS3 and CPS4 mediums. The sensitivity to localized corrosion of SR varies from one simulated environment to another. It has the best resistance to pitting corrosion in polluted CPS3 medium. In CPS1 (pH = 13) and CPS2 (pH = 11.6) polluted by 3% NaCl, the tendency to pitting corrosion is the same. The localized attack is more pronounced in polluted CPS4 (pH=12.7). These results demonstrate that there are no limit values of the pH and the content of Cl- ions for the initiation of pitting and / or uniform corrosion. Therefore, it is the chemical composition of the simulated medium which imposes the pH value and the Cl- content for systematic corrosion study of the SR in the simulated CPS

Corrosion Protection of Carbon Steel in Acidic Solution by Using Ylang-Ylang Oil as Green Inhibitor

The inhibition effect of ylang-ylang oil (YYO) and their adsorption on carbon steel surface in hydrochloric acid was realized at temperatures varying between 308 and 338 K by weight loss, EIS, and potentiodynamic polarization techniques. The tested compound showed inhibition efficiency that is superior 87 % for a concentration equal to 1.0 g/L. Polarization measurements indicate that the examined oil act as a mixed inhibitor with predominant anodic effectiveness and the protection efficiency increases with inhibitor concentration but this effect decreased with increasing of temperature. Data obtained from EIS studies were analyzed to model inhibition process through appropriate equivalent circuit models. The adsorption of YYO on carbon steel surface obeys Langmuir adsorption isotherm in acid medium and the activation were determined and discussed

Effect of amino acid on the passivation, corrosion and inhibition behavior of aluminum alloy in alkaline medium

The effect of L-methionine (L-Met) on the passivation and corrosion inhibition of aluminum alloy was investigated in carbonate medium in presence of chloride ions. This inhibitive action against the corrosion of aluminum in corrosive solution was investigated at 298 K using potentiodynamic polarization curves (PDP), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results obtained from the polarization curves reveal that the aluminum in alkaline medium exhibits a phenomenon of passivation with breakdown of passivity. Temperature effect on the corrosion behavior with the addition of (L-Met) studied in the range of temperature from 298 to 328 K. The inhibition efficiency decreases slightly with the increase in the temperature. Results show that L-Met is a good inhibitor and inhibition efficiency reach 87,23% at 10−3M. The electrochemical results are confirmed by scanning electron microscopy (SEM). The adsorption of this compound on aluminum surface obeys Langmuir’s adsorption isotherm. The kinetic and thermodynamic parameters were determined and discussed

Electrochemical and thermodynamic study of the inhibitory efficacy of Methanol extracts of the Rind and Leaves of Grapefruit plant on the corrosion of carbon steel in an acidic medium

The inhibition potentials of methanol extracts of leaves (GFL) and rind (GFR) of Grapefruit plant was investigated by evaluating the corrosion behaviour of carbon steel metal immersed in 1.0 M HCl solution containing various concentrations of the extracts. Electrochemical technical, Gravimetric measurements and adsorption characterization were utilized to evaluate the corrosion inhibition and adsorption properties of the extracts. The results revealed that the studied extracts were efficient inhibitors of corrosion in carbon steel immersed in 1.0 M HCl and that the inhibition efficiency depends on the concentration of the extracts. The activation energies and the negative free energy of adsorption obtained from the adsorption of methanol extracts of leaves and rind of Grapefruit indicate that the methanol extracts were physically adsorbed on the surface of the carbon steel and that the adsorption is endothermic, spontaneous, strong and fit excellently with the assumptions of the Langmuir adsorption isotherm. The activation parameters are determined and discussed. 

Experimental and theoretical investigation of 4-Methyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one on the corrosion and inhibition behavior of steel in acidic solution

The effect of 4-methyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one (MDBO) on the inhibition of steel corrosion was studied in an acid medium. This inhibiting action against corrosion of steel in a corrosive solution was studied at 298 K using potentiodynamic polarization curves, weight loss measurements and electrochemical impedance spectroscopy (EIS) and complementary with density functional theory (DFT) methods. The inhibiting action increases with the concentration of (MDBO) compound to attain 89.53% at 10-3 M. Polarization measurements also show that the 4-methyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one (MDBO) acts essentially as a mixte type inhibitor. The cathodic curves indicate that the reduction of proton at the steel surface happens with an activating mechanism. (MDBO) adsorbs on the steel surface according to Langmuir adsorption model. Effect of temperature is also made in the 298–328 K range. Activation parameters are determined and discussed. For establish the correlation between experimental data and theoretical results, some quantum chemical parameters for the tested compound were evaluated for supply more idea on the mechanism of inhibition of the dissolution process

Corrosion inhibition of carbon steel in acidic medium by Grapefruit oil extract

Carbon steel is widely used in various fields such as the field of agri-food their use in tins and materials used in the food producing seen this material and susceptible to corrosion phenomena are in their environmental which produces toxic compounds in the environmental medium of this material. To this end we investigated in this direction by study of the inhibition of the phenomenon of corrosion of this material. Grapefruit oil extract (GO) was tested as corrosion inhibitor for mild steel in 1M HCl. Electrochemical impedance spectroscopy (EIS) method are used. The inhibiting action increases with the concentration of the tested inhibitor. The highest efficiency 86.15% is obtained at 1g/L of GO. Effect of temperature is also studied between 298 K and 328 K; GO presents best inhibition efficiency even at elevated temperature, GO is adsorbed on the steel surface according to a Langmuir isotherm adsorption model. The thermodynamic data of activation are determined. In this study fatty acid composition contents of Grapefruit were determined. The used methods indicate that the Grapefruit oil extract is a good inhibitor in 1.0 M HCl. Some thermodynamic functions of the carbon steel dissolution process in acid medium were also determined and discussed

Electrochemical and quantum studies of the radicalizing mechanism for electrodegradation of methidation pesticide

We will study in this paper the influence of the current density on the oxidation of Methidathion for values of i equal to 20mA/cm², 40mA/cm² and 60mA/cm². For the realization of this work, we chose the electrode of boron doped diamond (BDD). It is recognized like anodes of high oxygen overpressure, support of this fact the generation of the radicals hydroxyls (OH•) by the oxidation of water. The study shows that has better current density applied for the degradation of Methidathion is 60mA/cm². The acceleration of the kinetics of degradation of Méthidathion associated the increase of current, can be explained by a more production important of radicals OH•.A theoretical part also was carried out using the calculation Gaussian 03W program. We determined the geometry of this molecule, the point charges for determine be various points of adsorption of the molecule on the surface of the electrode and we also determined the profile energetic of molecule of Methidathion to confirm that the mechanism is concerted, indeed, no stable intermediary was theoretically localized. These calculations were carried out by method RHF on the level 6-31+G(2d, 2p)

Investigation of the Inhibition Effect of 1-2-(4-Nitro Phenyl) 2-oxoethyl) -4N-Nmethyl) Picolinium Bromide On Carbon Steel Corrosion in Hydrochloric Acid Medium.

The corrosion behavior of C38 steel in HCl solution with different concentration of newly synthesized Picolinium-based Ionic liquids, 1-2-(4-Nitro Phenyl) 2-oxoethyl) -4N-Nmethyl) Picolinium Bromide (NPOMPB), was investigated by weight loss and electrochemical measurements. The effect of temperature on the corrosion behavior with the addition of (NPOMPB), was studied in the temperature range 298–328 K. Results obtained reveal that (NPOMPB) performs excellently as good corrosion inhibitor for C38 steel in 1.0 M HCl. Potentiodynamic polarization studies have shown that (NPOMPB) inhibition efficiency was found to increase with increase of the inhibitor concentrations to reach 96.5 % at 10-3M of (NPOMPB), due to the adsorption of the inhibitor molecules on the metal surface and the adsorption follows Langmuir’s adsorption isotherm. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability. To elaborate the mechanism of corrosion inhibition, the kinetic and thermodynamic parameters for Carbon steel corrosion and inhibitor adsorption, respectively were determined and discussed.  The Optical microscopy (OM) was used for its morphological studies. Of the surface film was applied in order to get better understanding about the relationship between the inhibition efficiency and molecular structure and also to show the presence of the interfacial elements

Kaempferol as a corrosion inhibitor on mild steel in HCl

The Kaempferol (KFR), is investigated as a corrosion inhibitor for C38 steel in HCl solution using impedance spectroscopy, polarization curves measurement and weight loss studies. Results obtained reveal that the Kaempferol performs excellently as a corrosion inhibitor for C38 steel in 1.0 M HCl and indicate that the inhibition efficiency increases with the concentration of the inhibitor to reach 96.0 % at 2.10-3 M of the Kaempferol. The effect of temperature on the corrosion behavior of carbon steel in 1 M HCl was also studied. Polarization curves showed that the Kaempferol behaves as a mixed-type inhibitor. The adsorption of the inhibitor on the carbon steel surface obeyed the Langmuir adsorption isotherm. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability. Data obtained from EIS technique, were analyzed to model the corrosion inhibition process through appropriate equivalent circuit model; a constant phase element (CPE) has been used. The activation energy as well as other thermodynamic parameters for the inhibition process was calculated and discussed

The three ring 2-pyridyl-benzimidazole: a new organic compound kind of corrosion inhibitors of carbon steel in acidic media.

The influence of 2-pyridyl-benzimidazole (PB) on the corrosion of steel in 1M HCl solution has been studied by weight loss measurements, potentiodynamic polarization (EI) and impedance spectroscopy (EIS) methods. The inhibiting action increases with the concentration of (PB) compound to attain 95.63% at 10-3 M. Polarisation measurements also show that the 2-pyridyl-benzimidazole (PB) acts essentially as a mixte type inhibitor. The cathodic curves indicate that the reduction of proton at the steel surface happens with an activating mechanism. (PB) adsorbs on the steel surface according to Langmuir adsorption model. Effect of temperature is also made in the 298–328 K range. Activation parameters are determined and discussed