Corrosion Inhibition Characteristics Research Articles

Thermodynamic, chemical and electrochemical investigation of pandanus tectorius extract as corrosion inhibitor for steel in sulfuric acid solutions

The corrosion inhibition characteristics of pandanus tectorius extract on corrosion of steel in 1 M H 2 SO 4 were investigated using chemical and electrochemical measurements at various temperatures (30, 40, 50 and 60 °C). The effect of acid concentration on the corrosion rate of steel increases with acid concentration (0.25-2.00 M) showing first order corrosion reaction without changing the reaction mechanism. The results showed that when the concentration of pandanus tectorius extract increased from 5% to 15% (v:v), the rate of steel corrosion is decreased, which indicated that pandanus tectorius extract are good inhibitor for steel corrosion in 1 M H 2 SO 4 at 30 °C and attains 88.02% at 15% ( v : v ) from weight loss method. Electrochemical results showed that the investigated extract was acted as mixed type inhibitor. The free energy of adsorption Δ G ads for pandanus tectorius , indicates that the process was spontaneous and physically adsorbed (physisorption) onto the steel surface. Also, scanning electron microscopy (SEM) is used to support the obtained result. The trend of inhibition efficiency with temperature suggests physical adsorption of this extract on the corroding steel surface. Thermodynamic functions ∆ E app , ∆ H * and ∆ S * has been calculated and are discussed.

Effectiveness of some Nonionic Surfactants As Corrosion Inhibitors for Carbon Steel in Hydrochloric Acid Solution

The corrosion inhibition characteristics of the synthesized (I, II and III) nonionic surfactants on carbon steel corrosion in 1 M acid chloride have been investigated at 30 oC by potensiodynamic polarization. The obtained results show that compound I has the best efficiency at concentration 0.08 mmol/L while compound III is the best inhibitor at higher concentrations. The surface parameters of each synthesized surfactant were calculated from its surface tension including the critical micelle concentration (CMC), effectiveness of surfactant (π), maximum surface excess (Γmax) and the minimum surface area (Amin).

Benzimidazole derivatives as corrosion inhibitors for zinc in acid solution

The corrosion inhibition characteristics of 2-mercapto benzimidazole (MBI), 2-mercapto benzimidazolyl-ethyl acetate (MBEA), 2-hydroxy benzimidazole (HBI) and 2-hydroxy 5-nitro benzimidazole (HNBI) on zinc corrosion in 0.1 M hydrochloric acid were investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency increased with increase in inhibitor concentration but decreased with increase in temperature. The adsorption of MBI and MBEA obeyed Langmuir’s adsorption isotherm but HBI and HNBI followed Temkin’s adsorption isotherm. Thethermodynamic functions for adsorption processes were evaluated. The existence of film on metal surface in presence of inhibitors was established by scanning electron microscopy (SEM) images.

Synergistic effect of mixed cationic and anionic surfactants on the corrosion inhibitor behavior of mild steel in 3.5% NaCl

The corrosion inhibition characteristics of cation-rich and anion-rich catanionic mixtures of cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), as corrosion inhibitor of mild steel (MS), in aqueous solution of 3.5% NaCl were investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscopy (SEM). Solutions of CTAB/SDS mixtures showed more appropriate inhibition properties compared to the solutions of the individual surfactants, due to strong adsorption on the metal surface and formation of a protective film. Potentiodynamic polarization investigations indicated that the inhibitors studied were mixed type inhibitors. Adsorption of the inhibitors on the mild steel surface obeyed the Flory–Huggins adsorption isotherm. Furthermore, the values of the adsorption free energy (ΔG°ads) in both mixtures decreased compared with a single surfactant which is attributed to stronger interactions in mixtures.

Coriandrum sativum L.—A novel green inhibitor for the corrosion inhibition of aluminium in 1.0 M phosphoric acid solution

The corrosion inhibition characteristics of aqueous extract of seeds of Coriandrum sativum L. (CSE) have been studied as an eco-friendly green inhibitor for corrosion control of aluminium in 1.0M phosphoric acid solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The effects of inhibitor concentration and temperature on the inhibition action were investigated. The adsorption of CSE on metal surface obeyed Langmuir adsorption isotherm. Polarization measurements showed that the CSE acted as mixed inhibitor in 0.5M and 2.0M phosphoric acid solution and the inhibitor molecules followed physical adsorption on the surface of aluminium. The surface morphology of aluminium, in the absence and presence of CSE in 1.0M phosphoric acid solution, was studied using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results obtained from Tafel extrapolation and A.C electrochemical impedance spectroscopy (EIS) techniques were in good agreement.

USE OF COMPOUNDS CONTAINING HETEROATOMS AS ELECTROCHEMICAL CORROSION INHIBITORS FOR COPPER IN HYDROCHLORIC ACID

The corrosion inhibition characteristics of N-[(Z)-1-phenylemethyleidene]-N-{2-[(2-{[(Z)-1phenylmethylidene]amino}phenyl)disulfanyl]phenyl} amine and N-[(Z)-1-(4-methylphenyl)methylidene]-N-{2-[(2-{[(Z)-1-(4methylphenyl)methylidene]amino}phenyl)disulfanyl]phenyl}amine on copper in HCl 15% solution was investigated using polarization and impedance methods. Electrochemical measurements indicate that Schiff bases have good inhibiting properties with mean efficiency of 98% at 0.5 mM concentration of inhibitors on copper corrosion in acid media. Tafel curves show that Schiff bases shifted the corrosion potential towards more positive values. Therefore, these compounds mainly affect the anodic process and decrease the corrosion rate. Impedance measurements for two Schiff bases show an increase of charge transfer resistance with increase of inhibitor concentration. The adsorption of Schiff bases on copper obeys the Langmuir adsorption isotherm. The negative values of ΔGads indicate that the inhibitors are strongly adsorbed on the copper surface. Other thermodynamic parameters (ΔHads, ΔSads) of the Schiff bases have been calculated.

Effect of the synthesis conditions on the formation of MgSrP2O7 and its characterisation for pigmentary application

In present research, we examined MgSrP2O7 as a new pigment with focus on its application as a corrosion inhibitor. The influence of the synthesis’ conditions on the product properties was examined. Samples were obtained by solid-state reaction and various homogenisation methods of initial components were employed (hand-milling, wet (ethanol/acetone) ball-milling and coprecipitation). Thermal behaviour of the reaction mixtures or dried coprecipitate was investigated using differential thermal and thermo-gravimetric analyses. Obtained samples were characterised with X-ray diffraction analysis, scanning electron microscopy and IR spectroscopy. Focusing on pigmentary application, specific properties of the samples were evaluated, such as thermal stability, mean particle size values and colour parameters, and also preliminary anticorrosion tests have been performed. Based on obtained results, MgSrP2O7 could be considered as a perspective corrosion inhibitor and homogenisation via coprecipitation can be rated as the best method of preparation of this composition, which provides the best thermal stability, the lowest particle size, the best homogeneity and the most promising corrosion inhibition characteristics (pH and ρ of the pigment aqua suspension) for the final product.

Influence of the deposition method, temperature and deposition time on the corrosion inhibition of lead dodecanoate coatings deposited on lead surfaces

Electrochemical impedance measurements have been used to investigate the influence of the deposition method, including time and temperature, upon the corrosion inhibition characteristics of lead dodecanoate coatings on lead electrodes. The results were analysed using multivariate statistics and show that, in general, these easily prepared coatings are very protective against corrosion. The temperature proves to be an important parameter for the quality and the corrosion inhibition efficiency of the coating. A comparison between two different electrochemically assisted deposition methods, immersion using a reduction pretreatment and cyclic voltammetry, does not show significant differences. Using the immersion technique at room temperature, the deposition time was tested as the third influencing parameter for the corrosion inhibition efficiency of the deposited lead dodecanoate coatings. A longer deposition time of the lead into the sodium dodecanoate solution provides a layer with a somewhat higher corrosion resistance.

Eco-friendly, cost-effective silica-based protective coating for an A6092/SiC/17.5p aluminum metal matrix composite

Aluminum-based, particulate-reinforced metal matrix composites (AMMCs) have been the most popular among the composite materials due to their low density and isotropic properties in addition to the superior mechanical, thermal and electrical properties. However, AMMCs have a more inhomogeneous structure than alloys due to presence of reinforcing particles. Such an inhomogeneous structure can enhance the pitting corrosion susceptibility, as well as cause a preferential dissolution of the interface between the matrix and the reinforcing particles. This paper discusses the possibility of improving the corrosion resistance of ALCOA peak-aged Al6092/SiC/17.5p composite using silica conversion coatings. The proposed coating is environmentally friendly and cost-effective as it based on sodium metasilicate solutions of different concentrations (10, 20, 50 and 100g/l). Electrochemical impedance spectroscopy (EIS), linear polarization and cyclic voltammetery tests were used to investigate the corrosion behavior of the composite in 3.5% NaCl. Results showed that the film formed due to a simple immersion in a silica solution is very effective for improving the localized corrosion resistance by forming a barrier protective layer. The polarization resistance (Rp) for the uncoated composite was measured by EIS to be approximately 5.0×103Ωcm2. The Rp was enhanced by about three times after silica coating with a distinct improvement in the localized corrosion resistance. The optimum silica concentration to provide the highest corrosion inhibition characteristics has been determined to be 50g/l. Increasing the silica concentration to 100g/l has an adverse effect on the corrosion resistance.

Adsorption and inhibition properties of mild steel corrosion in ground water medium by 1‐(4‐methoxy benzyl)‐1H‐imidazole: experimental and theoretical investigations

Corrosion inhibitive performance of a newly synthesized imidazole derivative 1‐(4‐methoxy benzyl)‐1H‐ imidazole (MBI) on mild steel in ground water medium was investigated. Gravimetric and electrochemical measurements incorporated with quantum chemical calculation were used to study the corrosion inhibition characteristics of MBI in ground water medium. The inhibition efficiency increased with the increase of inhibitor concentration, while the adsorption followed the Langmuir isotherm. To clarify the inhibition efficiency of MBI for the corrosion prevention of mild steel in ground water medium, a density functional theory study was also carried out using 6‐31 G* basis set. Quantum chemical descriptors such as the energy of highest occupied molecular orbital, energy of lowest unoccupied molecular orbital, chemical potential (Pi), electronegativity (χ), global hardness (η), softness (σ), the energy gap (ΔE), and dipole moment (μ) were calculated. The quantum chemical calculations based on density functional theory results show that the new imidazole derivative can adsorb on the mild steel surface, which forms a barrier against corrosion. Thus, MBI acts as a good corrosion inhibitor for mild steel in ground water medium. Copyright © 2012 John Wiley & Sons, Ltd.

New eco-friendly cationic surfactants: Synthesis, characterization and applicability as corrosion inhibitors for carbon steel in 1 N HCl

Three new environmental friendly surfactants of cationic type were synthesized using natural vanillin. Their chemical structures were determined using elemental, IR, 1H NMR and 13C NMR spectroscopic analyses. The surface activity of the synthesized surfactant solutions was determined using surface and interfacial tension measurements at 25 °C. The emulsification powers of these surfactants were measured against light paraffin oil. The biodegradation ability of the surfactants reached the maximum (75%) within 21 days. Corrosion inhibition characteristics of the green surfactants were determined on carbon steel in 1 N HCl at 25 °C using gravimetric and potentiodynamic techniques. The adsorption of inhibitors on carbon steel in 1 N HCl follows Langmuir adsorption isotherm. Thermodynamic adsorption parameters ( K ads, Δ G ads) of studied inhibitors were calculated using the Langmuir adsorption isotherm. The Tafel polarization results indicate that the inhibitors act as mixed inhibitors. The inhibition efficiency increases with an increase in the inhibitor dose, side chain length and surface activity of the inhibitors. The maximum inhibition efficiencies ranged between 95.09% and 98.53% at 400 ppm.

Inhibition effects of acetyl coumarines and thiazole derivatives on corrosion of zinc in acidic medium

The corrosion inhibition characteristics of acetyl coumarine (AC), bromo acetyl coumarine (BAC) and thiazole derivatives (BTMQ and BTCQ) on the corrosion of zinc in 0·1 M HCl solution were investigated by weight loss, potentiodynamic polarization and impedance techniques. The inhibition efficiency increased with increase in inhibitor concentration upto 5 ×10 − 4 M, then gave almost same inhibition efficiency. The polarization measurements indicated the mixed nature of inhibitors. The adsorption of compounds obeyed Langmuir’s adsorption isotherm. The thermodynamic functions for adsorption processes were evaluated.

Inhibition of Mild Steel Corrosion Using L-tryptophan and Synergistic Surfactant Additives

The corrosion inhibition characteristics of nitrogen containing amino acid L-tryptophan on mild steel in 0.1 M HCl solution, in the temperature range of 30-50 o C, was studied by weight loss and potentiodynamic polarization measurements. L-tryptophan significantly reduces the corrosion rates of mild steel; the maximum inhibition efficiency being 83% at 50 o C in presence of inhibitor concentration of 500 ppm. The effect of the addition of very small concentrations of anionic surfactant, sodium dodecyl sulfate (SDS), and of cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), on the corrosion inhibition behavior of L-tryptophan was also studied. The inhibition efficiency (IE) of L-tryptophan significantly improved in presence of both surfactants. The effect of SDS and CTAB on the corrosion inhibition behavior of L-tryptophan appears to be synergistic in nature, the values of synergism parameter being greater than unity. The adsorption of inhibitors on mild steel surface obeyed Langmuir’s adsorption isotherm. The calculated thermodynamic parameters for adsorption reveal a strong interaction between the inhibitors and the mild steel surface. The results obtained by electrochemical studies are consistent with the results of the weight loss measurements. L-tryptophan acts more anodic than cathodic inhibitor.

Corrosion inhibition of 6061 Al–15 vol. pct. SiC(p) composite and its base alloy in a mixture of sulphuric acid and hydrochloric acid by 4-(N,N-dimethyl amino) benzaldehyde thiosemicarbazone

The corrosion inhibition characteristics of 4-(N,N-dimethylamino) benzaldehyde thiosemicarbazone (DMABT) on the corrosion behavior of 6061 Al–15 vol. pct. SiC(p) composite and its base alloy were studied at different temperatures in acid mixture medium containing varying concentrations of hydrochloric acid and sulphuric acid using Tafel extrapolation technique and ac impedance spectroscopy (EIS). The effect of inhibitor concentration, temperature and concentration of the acid mixture media on the inhibitor action was investigated. It was found that inhibition efficiencies increase with the increase in inhibitor concentration, but decrease with the increase in temperature and with the increase in concentration of the acid media. Thermodynamic parameters for dissolution process were determined. The adsorption of DMABT on both the composite and base alloy was found to be through physisorption obeying Freundlich adsorption isotherm.

Corrosion inhibition of aluminum by novel phthalocyanines in hydrochloric acid solution

The corrosion inhibition characteristics of quaternized 1,(4)-tetrakis[(2-mercapto)pyridine]phthalocyanine (I) and 2,3-octakis[(2-mercapto)pyridine] phthalocyanine (II) on aluminum in 0.1 M HCl solution has been studied by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The maximum inhibition efficiency was obtained for compound I with two-electrochemical techniques applied. Langmuir isotherm fits well the experimental data. The inhibition efficiency increases with increase in the phthalocyanine concentration, but decreases with an increase in temperature. The phthalocyanines act predominately as cathodic inhibitor.

A theoretical study of some hydroxamic acids as corrosion inhibitors for carbon steel

The corrosion inhibition characteristics of two hydroxamic acids, i.e., oxalyl-dihydroxamic acid (C2) and pimeloyl-1,5-di-hydroxamic acid (C7), on carbon steel has been studied using density functional theory (DFT). Quantum chemical parameters such as highest occupied molecular orbital energy ( E HOMO), lowest unoccupied molecular orbital energy ( E LUMO), and energy gap (Δ E) have been calculated using B3LYP/6-31 + G∗∗ basis set. The relationship between the inhibition efficiency and quantum chemical parameters has been discussed in order to elucidate the inhibition mechanism of these compounds.

Electrochemical investigation and modeling of corrosion inhibition of aluminum in molar nitric acid using some sulphur-containing amines

Chemical and electrochemical measurements incorporated with quantum chemical calculations and molecular dynamics simulations were used to study the corrosion inhibition characteristics of some thiosemicarbazone derivatives on the inhibition of aluminum corrosion in 1.0 M HNO 3. Polarization curves demonstrated that the thiosemicarbazone derivatives were of mixed-type inhibitors. EIS plots indicated that the addition of thiosemicarbazone derivatives increases the charge-transfer resistance of the corrosion process, and hence the inhibition performance. The molecular dynamics simulation results show that the three thiosemicarbazone derivatives can adsorb on the A 2O 3 (1 1 1) surface through the sulphur and nitrogen atoms as well as π-electrons in the pyridyl structure.

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series – Part I. Tafel polarisation, ICP-AES and EFM studies

The corrosion inhibition characteristics of non-ionic surfactants of the TRITON-X series, known as TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on iron in 1.0 M HCl solution were studied. Measurements were conducted in 1.0 M HCl solutions without and with various concentrations of the three selected surfactants using chemical (ICP-AES method of analysis of dissolved cations) and electrochemical (Tafel polarisation and EFM) techniques at 25 °C. These measurements were complemented with SEM and EDX examinations of the electrode surface. Polarisation data showed that the non-ionic surfactants used in this study acted as mixed-type inhibitors with cathodic predominance. The protection efficiency increased with increase in surfactant concentration. Maximum protection efficiency of the surfactant was observed at concentrations around its CMC. From their molecular structure, these surfactants may adsorb on the metal surface through two lone pairs of electrons on the oxygen atoms of the hydrophilic head group.

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 inhibition of aluminum 6063 using some pharmaceutical compounds

The corrosion inhibition characteristics of some pharmaceutical compounds on aluminium 6063 in 0.5 mol l−1 H3PO4 has been studied using weight loss and galvanostatic polarization techniques. Results showed that the inhibition occurs through adsorption of the inhibitor molecules on the metal surface. The inhibition efficiency increased with increasing inhibitor concentration, but decreased with increasing temperature. The adsorption of first group pharmaceutical compounds on the metal surface is found to obey Frumkin’s adsorption isotherm, but the adsorption of second group pharmaceutical compounds is found to obey Temkin’s adsorption isotherm. Thermodynamic parameters for adsorption process were determined. Galvanostatic polarization studies showed that first and second groups’ pharmaceutical compounds are mixed-type inhibitors and the results obtained from the two techniques are in good agreement.