Inhibition Efficiency Values Research Articles

Corrosion Inhibition of Carbon Steel in Open Recirculating Cooling Water System of Petroleum Refinery by Thiourea and Imidazole in Presence of Zinc (II) Sulphate

The inhibiting action of thiourea and imidazole towards corrosion for carbon steel in open recirculating cooling system (ORCS) of Numaligarh Refinery Limited (NRL) , Golaghat , Assam,India has been studied in presence of Zn2+(as ZnSO4.7H2O) by weight loss and potentiodynamic polarization methods. The values of inhibition efficiency from weight loss method are in good agreement with those obtained from polarization studies. Polarization study indicates that imidazole retards the cathodic corrosion reaction where as thiourea inhibits anodic corrosion reaction in these particular blends of inhibitors. SEM and EDS study confirm the formation of an adsorbed protective film on the carbon steel surface.

Thermodynamic, chemical and electrochemical investigations of 2-mercapto benzimidazole as corrosion inhibitor for mild steel in hydrochloric acid solutions

The inhibiting action of 2-mercapto benzimidazole (2MBI) on mild steel in 1.0M hydrochloric acid has been investigated at 308K using weight loss measurements and electrochemical techniques (impedance spectroscopy and potentiodynamic polarisation). Inhibition efficiency increases with 2MBI concentration to attain 98% at 10−3M. Polarisation curves indicate that 2MBI acts as a mixed-type inhibitor. Inhibition efficiency values obtained from various methods were in good agreement. EIS measurements showed an increase of the transfer resistance with the inhibitor concentration. The temperature effect on the corrosion behaviour of steel in 1.0M HCl without and with the 2MBI at various concentrations was studied in the temperature range from 308 to 353K. Thermodynamic parameters such as heat of adsorption (ΔHads∘), entropy of adsorption (ΔSads∘) and adsorption free energy (ΔGads∘) have been calculated. Kinetic parameters for the corrosion reaction at different concentrations of 2MBI were determined. Adsorption of 2MBI on the mild steel surface in 1.0M HCl follows the Langmuir isotherm model.

A newly synthesized glycine derivative to control uniform and pitting corrosion processes of Al induced by SCN − anions – Chemical, electrochemical and morphological studies

A newly synthesized glycine derivative (termed GlyD), 2-(4-(dimethylamino)benzylamino)acetic acid hydrochloride, was used to inhibit uniform and pitting corrosion processes of Al in 0.50 M KSCN solutions (pH 6.8) at 25 °C. For uniform corrosion inhibition study, Tafel extrapolation, linear polarization resistance and impedance methods were used, complemented with SEM examinations. An independent method of chemical analysis, namely ICP-AES (inductively coupled plasma atomic emission spectrometry) was also used to test validity of corrosion rate measured by Tafel extrapolation method. GlyD inhibited uniform corrosion, even at low concentrations, reaching a value of inhibition efficiency up to 97% at a concentration of 5 × 10 −3 M. Results obtained from the different corrosion evaluation techniques were in good agreement. This new synthesized glycine derivative was also used to control pit nucleation and growth on the pitted Al surface based on cyclic polarization, potentiostatic and galvanostatic measurements. The pitting potential ( E pit) and the repassivation potential ( E rp) increased by the addition of GlyD. Thus GlyD suppressed pit nucleation and propagation. Nucleation of pit was found to take place after an incubation time ( t i). The rate of pit nucleation and growth decreased with increase in inhibitor concentration. Morphology of pitting was also studied as a function of the applied anodic potential and solution temperature. Cross-sectional view of pitted surface revealed the formation of large distorted hemispherical and narrow deep pits. GlyD was much better than Gly in controlling uniform and pitting corrosion processes of Al in these solutions.

Inhibition by Jasminum nudiflorum Lindl. leaves extract of the corrosion of cold rolled steel in hydrochloric acid solution

The inhibition effect of Jasminum nudiflorum Lindl. leaves extract (JNLLE) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) was investigated by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results show that JNLLE acts as a very good inhibitor, and the inhibition efficiency increases with the concentration of JNLLE. The adsorption of JNLLE obeys Langmuir adsorption isotherm. Values of inhibition efficiency obtained from weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) are in good agreement. Polarization curves show that JNLLE behaves as a mixed-type inhibitor in hydrochloric acid. EIS shows that charge-transfer resistance increase and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The adsorbed film on CRS surface containing JNLLE inhibitor was also measured by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). A probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.

Electrochemical and thermodynamic investigation of diniconazole and triadimefon as corrosion inhibitors for copper in synthetic seawater

This paper presents the investigation of diniconzole and triadimefon as chemical corrosion inhibitors for freshly polished copper in synthetic seawater (3.5% NaCl solution). Determination of weight loss, polarization curves, electrochemical impedance spectroscopy (EIS), and SEM, were performed to analyze the inhibiting performance of these compounds. Polarization curves show that they act as mixed-type inhibitors. EIS indicates that an adsorption film of the inhibitors is formed on copper surface. The highest values of inhibition efficiency are respectively, 99.2% and 97.3% at 100 mg/L concentration. Thermodynamic calculation suggests that chemisorptions between the compounds and copper are accordance with Langmuir adsorption isotherm.

The inhibition effect of 2,4,6-tris (2-pyridyl)-1,3,5-triazine on corrosion of tin, indium and tin–indium alloys in hydrochloric acid solution

The influence of 2,4,6-tris (2-pyridyl)-1,3,5-triazine (TPTZ) on the corrosion of tin, indium and tin–indium alloys in 0.5 M HCl solution at different temperatures was studied. Potentiodynamic cathodic polarization and extrapolation of cathodic and anodic Tafel lines techniques were used to obtained experimental data. In the case of tin, the percent inhibition efficiency (IE%) increases as both concentration of TPTZ and temperature are increased. The value of activation energy ( E a) is smaller in the presence of TPTZ than that in uninhibited solution, and decreases with increasing the concentration. However, the effect of TPTZ on indium and the investigated alloys exhibited similar behavior; so, the maximum inhibition efficiency is observed at lowest concentration (10 −6 M) of TPTZ. Then, the value of inhibition efficiency starts to decrease gradually with increasing TPTZ concentration than that of 10 −6 M. But at higher concentration (10 −3 M) the corrosion current density ( I corr) is still lower than that in uninhibited solution. SEM photographs support that the higher inhibition efficiency is observed at 10 −6 M of TPTZ. The plots of ln K versus 1/ T in the presence of the TPTZ in the case of tin, the inhibitor showed linear behavior. The standard enthalpy, Δ H° ads., entropy, Δ S° ads. and free energy changes of adsorption Δ G° ads. were evaluated using Frumkin adsorption isotherm.

Understanding Corrosion Inhibition of Mild Steel in Acid Medium by Some Furan Derivatives: A Comprehensive Overview

The inhibition performance of some furan derivatives, namely, methyl 2-furoate, ethyl 2-furoate, and amyl 2-furoate on mild steel in normal hydrochloric acid medium ( HCl) at , was studied by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation measurements (EFM). Furan derivatives inhibit the acidic corrosion even at very low concentrations, reaching a value of inhibition efficiency up to 93% at a concentration of . The results obtained from the different corrosion evaluation techniques are in good agreement. Polarization curves indicate that the studied furan derivatives are mixed-type inhibitors. Data obtained from EIS measurements were analyzed to model the corrosion inhibition process through an appropriate equivalent circuit model. A constant phase element has been used. The adsorption of furan derivatives on the steel surface in HCl solution was found to obey Langmuir’s adsorption isotherm with a negative value of the free energy of adsorption . Molecular dynamics simulations were carried out to establish the inhibition mechanism.

Surface Analysis of Inhibitor Film Formed by Poly(Vinyl Alcohol) on Stainless Steel in Sodium Chloride Solution

The corrosion inhibition of stainless steel in 0.9% NaCl solution in presence of poly(vinyl alcohol) (PVA) is discussed according to electrochemical measurements, such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS).The morphology of the surface was analyzed using Scanning Electron Microscopy (SEM). The composition of the layer formed on stainless steel surface was estimated using X-ray Photoelectron Spectroscopy (XPS) technique. Electrochemical measurements indicated that the presence of PVA in NaCl solution decreases the corrosion current and increases the polarization resistance. The values of inhibition efficiency obtained from polarization curves and EIS measurements are in good agreement. In absence and in presence of PVA, SEM images showed that the stainless steel surface was covered with a non-uniform layer and a uniform adsorbed film, respectively. XPS analysis indicated that the surface layer consists of PVA containing a small amount of other elements, such as Na and Cl.

Corrosion inhibition of aluminum in 2.0 M hydrochloric acid solution by the acetone extract of red onion skin

The inhibition efficiency of acetone extract of red onion skin on aluminium in hydrochloric acid solutions has been evaluated by weight loss techniques. Values of inhibition efficiency obtained are dependent upon the concentration of inhibitor and temperature. Generally, inhibition was found to increase with inhibitor concentration, half-life, activation energy but decrease with temperature and first-order rate constant at the temperatures studied. Physical adsorption mechanism has been proposed for the inhibition and Langmuir adsorption isotherm was obeyed. The compound responsible for the inhibitory action of red onion skin is Quercetin. Red onion skin is an inhibitor of aluminium corrosion in 2 M hydrochloric acid solution. Key words: Corrosion inhibition, aluminium, weight loss, red onion skin, hydrochloric acid.

INHIBITION OF IRON CORROSION USING TWO NEWLY SYNTHESIZED SCHIFF BASE COMPLEXES IN ETHANOLIC HYDROCHLORIC ACID MEDIA

Two different Schiff base complexes were tested as corrosion inhibitors for iron in hydrochloric acid medium (prepared in ethanol) at different temperatures using potentiodynamic polarization measurements. The obtained results reveal that increasing HCl concentration at 35°C increased the anodic and cathodic current density values. Moreover, anodic current density peak was observed at concentrations >1M HCl. However, the magnitude of corrosion rate CR in presence of complexes is suppressed as its tendency to increase with acid concentration. On the other hand, the values of corrosion potentials (around −300 mV(SCE)) were not affected by the addition of any complex. The inhibition efficiency values increase with an increase in complex concentrations in which Hg- complex achieves higher protection efficiency than Zn-complex. The adsorption processes follow the Langmuir isotherm. Concerning the effect of temperature, results demonstrate that increasing the temperature leads to an increase in the corrosion rate of iron and a decrease in the inhibition efficiencies of the complexes. The rise in activation energy Ea values in presence of the complexes explains the corrosion inhibition obtained through physical adsorption. Also, higher ∆H° values indicate higher protection efficiency. ∆S° has negative value for the blank and the complexes solutions indicating that the system passes from a more to a less orderly arrangement.

Corrosion Inhibition and Adsorption Characteristics of Tarivid on Mild Steel in H2SO4

The corrosion inhibition and adsorption characteristics of (+/‐)‐9‐fluoro‐2,3‐dihydro‐3‐methyl‐10‐(4‐methyl‐1‐piperazinyl)‐7‐oxo‐7H‐pyrido[1,2,3‐de]‐1,4‐benzoxazine‐6‐carboxylic acid (Tarivid) on the corrosion of mild steel has been studied using thermometric and gasometric methods. The study reveals that tarivid inhibits the corrosion of mild steel in H2SO4. The values of inhibition efficiency of tarivid were found to increase as its concentration increased but decreased with increase in temperature. Activation energies of the inhibited corrosion of mild steel ranged from 39.05 to 50.61 kJ/mol. Values of enthalpy change and free energy of adsorption were negative which indicated exothermic and spontaneous adsorption process. Physical adsorption mechanism is proposed from the obtained kinetic and thermodynamic parameters. Langmuir adsorption isotherm model is obeyed from the fit of the experimental data.

Corrosion Mechanism of Low-Carbon Steel in Industrial Water and Adsorption Thermodynamics in the Presence of Some Plant Extracts

The effects of radish leaves and black cumin as plant extracts on the corrosion behavior of low-carbon steel in industrial water in the temperature range of 30 to 80 °C and velocity range of 1.44 to 2.02 m s−1 using potentiodynamic polarization, electrochemical impedance spectroscopy, and mass loss measurements have been investigated. The inhibition efficiency increased with increasing concentration of the plant extracts up to a critical value but it slightly decreased with increasing temperature. Inhibition efficiency values obtained from mass loss and potentiodynamic data were in reasonable agreement. Potentiodynamic polarization clearly indicated that radish leaves and black cumin extracts acted as anodic inhibitors. The adsorption behavior was found to obey the Flory-Huggins isotherm model. The associated activation parameters and thermodynamic data of adsorption were evaluated and discussed. The results show that radish leaves and black cumin could serve as effective inhibitors for low-carbon steel in industrial water media, with black cumin providing better protection than radish leaves.

Investigation effect of benzotriazole on the corrosion of brass-MM55 alloy in artificial seawater by dynamic EIS

The electrochemical behavior of brass-MM55 alloy was studied in artificial seawater with benzotriazole by using a novel method called dynamic electrochemical impedance spectroscopy (DEIS). This method gives possibility to investigate the protection of metals in corrosive medium by using inhibitors in galvanostatic conditions for a long time. Instantaneous impedance spectra for brass-MM55 were recorded for 10 h in artificial seawater for different concentration of benzotriazole. It was found that a few hours were not enough for the accurate calculation of corrosion inhibition. Also with this method it is possible to figure out how the charge transfer resistance (R ct) changes by the time. Usefulness of the DEIS technique in the investigation of non-stationary phenomena has been proved in the field of inhibitor research. All studies clearly show that benzotriazole inhibits the corrosion of brass-MM55 alloy in artificial seawater solution and the value of inhibition efficiency increases with increasing concentration of benzotriazole.

Inhibitive and adsorption properties of ethanol extract of Colocasia esculenta leaves for the corrosion of mild steel in H2SO4

Inhibitive and adsorption properties of ethanol extract of Colocasia esculenta for the corrosion of mild steel in H2SO4 were investigated using weight loss, hydrogen evolution and IR methods of monitoring corrosion. The results obtained indicates that ethanol extract of C. esculenta is a good inhibitor for the corrosion of mild steel in H2SO4 and its inhibitive action is attributed to its phytochemical constituents which aided its adsorption on the surface of mild steel. Calculated values of activation energy and inhibition efficiency at 303 and 333 K revealed that the mechanism of adsorption of ethanol extract of C. esculenta on mild steel surface is physical adsorption. Also the adsorption of the inhibitor on mild steel surface was found to be spontaneous, endothermic and consistent with the assumptions of Langmuir adsorption isotherm. Key words: Corrosion, mild steel, inhibition, Colocasia esculenta.

Corrosion control of mild steel using 3,5-bis(4-methoxyphenyl)-4-amino-1,2,4-triazole in normal hydrochloric acid medium

The inhibition performance of the 3,5-bis(4-methoxyphenyl)-4-amino-1,2,4-triazole (4-MAT) on mild steel in normal hydrochloric acid medium (1 M HCl) at 30 °C was tested by weight loss, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. This organic compound inhibits the acidic corrosion even at very low concentration, reaching a value of inhibition efficiency up to 98% at a concentration of 3 × 10 −4 M. The results obtained from the different corrosion evaluation techniques are in good agreement. Polarisation curves indicate that 4-MAT is a mixed inhibitor, affecting both cathodic and anodic corrosion currents. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through appropriate equivalent circuit model, a constant phase element (CPE) has been used. The adsorption of 4-MAT on the steel surface, in 1 M HCl solution, obeys to Langmuir’s isotherm with a very high negative value of the free energy of adsorption Δ G° ads (chemisorption). X-ray photoelectron spectroscopy (XPS) was carried out to establish the mechanism of corrosion inhibition of mild steel in 1 M HCl medium in the presence of 3,5-bis(4-methoxyphenyl)-4-amino-1,2,4-triazole (4-MAT).

Inhibition of corrosion of mild steel in acidic medium using ethanol extract of Aloe vera

PurposeThe purpose of this paper is to study the effect of concentration of H2SO4 on the corrosion of mild steel and to investigate the inhibitive properties of Aloe vera for mild steel corrosion. The study also seeks to investigate the possibility of using Aloe vera as a green corrosion inhibitor for mild steel.Design/methodology/approachGasometric (Hydrogen evolution) and thermometric methods of corrosion monitoring have been adopted for the study. The study was conducted at 303 and 333 K and the concentrations of inhibitor used were 0.1, 0.2, 0.3 and 0.4 g/L. The inhibitor was prepared by using alcohol extract of moisture free samples of Aloe vera. The functional groups present in the extract have been determined using infra red spectrophotometer. Thermodynamic and adsorption theories have been used to interpret the data.FindingsEthanol extract of Aloe vera is a good inhibitor for mild steel corrosion at 303 and 333 K. The inhibitor acts by chemical adsorption isotherm. Functional groups identified in the extract are found to played dominant role in the adsorptive and inhibitive potentials of this extract. Values of inhibition efficiency obtained from gasometric and thermometric analysis were comparable.Research limitations/implicationsFurther study on synergism with the view of enhancing the inhibition efficiency of Aloe vera extract and the used of other analytical methods may reveals a wealth of information on the possibilities of transforming this research for field application.Originality/valueThe paper provides information on the use of Aloe vera as a green corrosion inhibitor. It has not been published elsewhere.

Quantum chemical study of the inhibition of the corrosion of mild steel in H2SO4 by some antibiotics

The inhibition efficiency of some antibiotics against mild steel corrosion was studied using weight loss and quantum chemical techniques. Values of inhibition efficiency obtained from weight loss measurements correlated strongly with theoretical values obtained through semi empirical calculations. High correlation coefficients were also obtained between inhibition efficiency of the antibiotics and some quantum chemical parameters, including frontier orbital (E (HOMO) and E (LUMO)), dipole moment, log P, TNC and LSER parameters (critical volume and dipolar-polarisability factor), which indicated that these parameters affect the inhibition efficiency of the compounds. It was also found that quantitative structure activity relation can be used to adequately predict the inhibition effectiveness of these compounds.

Inhibition by tween-85 of the corrosion of cold rolled steel in 1.0 M hydrochloric acid solution

The inhibition effect of tween-85 on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) was studied by weight loss and potentiodynamic polarization methods. The results show that tween-85 is a good inhibitor in 1.0 M HCl and its maximum inhibition efficiency (IE) is 92% at very low concentration. Its adsorption obeys the Langmuir adsorption isotherm equation. The thermodynamic parameters of adsorption enthalpy (ΔH0), adsorption free energy (ΔG0) and adsorption entropy (ΔS0) were calculated and discussed. Polarization curves show that tween-85 acts as a mixed-type inhibitor in hydrochloric acid. IE values obtained from weight loss and polarization are consistent. The adsorbed film on a CRS surface containing an optimum dose of tween-85 was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). An inhibitive mechanism is proposed from the viewpoint of adsorption theory.

Inhibition of the Corrosion of Zinc in H2SO4 by 9-deoxy-9a-aza-9a-methyl-9a-homoerythromycin A (Azithromycin)

Inhibition of the corrosion of zinc in various concentrations (0.01 to 0.05 M) of H 2SO 4 was studied using weight loss and hydrogen evolution methods of monitoring corrosion. The results revealed that various concentrations of azithromycin (0.0001 to 0.0005 M) inhibited the corrosion of zinc in H 2SO 4 at different temperatures (303 to 333 K). The concentration of H 2SO 4 did not exert significant impact on the inhibition efficiency of azithromycin, but inhibition efficiencies were found to decrease with increase in the concentration of the inhibitor. Values of inhibition efficiency obtained from the weight loss measurements correlated strongly with those obtained from the hydrogen evolution measurements. The activation energies for the corrosion of zinc inhibited by azithromycin were higher than the values obtained for the blank. Thermodynamic data revealed that the adsorption of azithromycin on the surface of zinc was endothermic (values of enthalpies of adsorption were positive), spontaneous (values of free energies of adsorption were negative) and was consistent with the adsorption model of Langmuir.

Adsorption and Inhibitive Properties of Clarithromycin for the Corrosion of Zn in 0.01 to 0.05 M H2SO4

The corrosion of zinc in 0.01 to 0.04 M H 2SO 4 was studied using gravimetric and gasometric methods of monitoring corrosion. The results obtained indicate that clarithromycin is a good adsorption inhibitor for the corrosion of zinc in H 2SO 4. The inhibition efficiency of clarithromycin increases with increasing concentration but decreases with increasing temperature. There was no significant difference between the inhibition efficiencies of clarithromycin obtained at various concentrations of H 2SO 4 (P>0.5), but values of inhibition efficiency tend to decrease with increasing concentration of the acid. The adsorption of clarithromycin on zinc surface is endothermic, spontaneous and is best described by Langmuir adsorption isotherm. Calculated values of activation energies and free energies of adsorption indicate that the adsorption of clarithromycin on zinc surface supports the mechanism of physical adsorption.