Corrosion inhibition of ammonium molybdate for AA6061 alloy in NaCl solution and its synergistic effect with calcium gluconate

The corrosion inhibition of ammonium heltamolybdate (AH) and calcium gluconate (CG) for AA6061 alloy in 3% NaCl solution was investigated by the electrochemical measurements. It indicates that AH inhibits the corrosion of AA6061 alloy and acts as an anodic inhibitor. Maximum inhibition efficiency reaches 74.3% at the concentration of 1 × 10^?4 mol.l^?1 AH. The results of the electrochemical studies reveal AH is physically adsorbed on the AA6061 alloy surface and the adsorption follows Langmuir isotherm. The combination of AH and CG enhances the inhibition efficiency to 95.9%. The enhanced inhibition is attributed to the promotion of AH adsorption by CG. The mixture of AH and CG is a mixed‐type inhibitor and renders the corrosion potential to more positive values. Copyright © 2011 John Wiley & Sons, Ltd.     

Corrosion inhibition performance of 2-ethyl phenyl-2, 5-dithiohydrazodicarbonamide on Fe (110)/Cu (111) in acidic/alkaline solutions: Synthesis,experimental, theoretical,and molecular dynamic studies

Herein, 2-ethyl phenyl-2,5-dithiohydrazodicarbonamide (2EPDCA) was synthesised and tested as a corrosion inhibitor for mild steel (MS) and copper (Cu) in 1 M HCl and 3.5% NaCl, respectively. Fourier transform infrared spectroscopy (FT-IR) and (NMR) nuclear magnetic resonance (¹H, ¹³C) were used to identify the chemical structure. Both experimental and computational approaches have been conducted to evaluate inhibitor efficiency on both metal systems. The electrochemical results showed that the 2EPDCA inhibition efficiency for MS systems was 95% at 1 × 10^?2 M, while in copper systems it was 97.5% at 1 × 10^?2 M. The Langmuir adsorption isotherm was fitted using adsorption surface coverage data, and for inhibitor in both systems, the kind of adsorption was mixed (physisorption and chemisorption). Through scanning electron microscopy (SEM), EDX, and atomic force microscopy (AFM) tests, we have confirmed the presence of the inhibitor molecules on the metal surface in both systems. Quantum chemistry simulations indicate that the superior corrosion inhibition efficacy of 2EPDCA on copper compared to mild steel surfaces is attributable to the former's greater electron donating propensity on copper. The adsorption of 2EPDCA molecules on Fe (110) and Cu (111) surfaces was further verified by molecular dynamic simulations, with the former having a greater adsorption energy. The results indicate that the corrosion inhibitor was effective even in harsh conditions, and it can be thought of as a novel corrosion inhibitor for mild steel and copper that provides good protection.     

Inhibition effect of 1,3,5-tri-p-tolyl-1,3,5-triazene on the corrosion of brass in 0.5 M HCl solution

1,3,5-tri-p-tolyl-1,3,5-triazene was investigated as a corrosion inhibitor for brass in 0.5 M HCl solution using weight loss, potentiodynamic polarization, linear polarization resistance and electrochemical impedance spectroscopy. Data obtained from these methods showed average inhibition efficiency (76 %) at optimum concentration. The adsorption of the inhibitor on the brass surface follows the Frumkin adsorption isotherm.     

Inhibitive effect of chloroquine towards corrosion of mild steel in hydrochloric acid solution

Corrosion inhibition of mild steel (MS) by chloroquine (CQ) in 1 M HCl was investigated using weight loss, polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical techniques. The inhibitor showed 99 % inhibition efficiency at concentration of 3.1 × 10^?4 M. Polarization studies showed that CQ is a mixed-type inhibitor. Adsorption of inhibitor molecules on the MS surface showed Langmuir adsorption isotherm. Thermodynamic parameters led to the conclusion that adsorption is predominantly chemisorption. Quantum chemical calculations were carried out to investigate the corrosion-inhibiting property of CQ. Various parameters such as energy of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), softness of molecule, Mullikan charges on various atoms and number of electrons transferred from inhibitor molecule to metal were calculated and correlated with the inhibiting property of CQ.     

Influence of pyridazine derivative on corrosion inhibition of mild steel in acidic media

The inhibition behavior of 6-methyl-4,5-dihydropyridazin-3(2H)-one (MDP) on corrosion of mild steel in 1 M HCl and 0.5 M H₂SO₄ was investigated using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. The results indicated that the corrosion inhibition efficiency depends on concentration, immersion time, solution temperature, and the nature of the acidic solutions. It is also noted that MDP is at its the most efficient in 1 M HCl and least in 0.5 M H₂SO₄. The effect is more pronounced with MDP concentration. It is found that the inhibition efficiency attains 98 % at 5 × 10^?3 M in 1 M HCl and 75 % at 5 × 10^?2 in 0.5 M H₂SO₄. Polarization measurements showed that the MDP acts as a mixed inhibitor. EIS diagrams showed that the adsorption of MDP increases the transfer resistance and decreases the capacitance of the interface metal/solution. From the temperature studies, the activation energies in the presence of MDP were found to be superior to those in uninhibited medium. Finally, a mechanism for the adsorption of MDP was proposed and discussed.     

Ceratonia siliqua extract as a green corrosion inhibitor for copper and brass in nitric acid solutions

ABSTRACT

The influence of extract of ceratonia siliqua extract on the corrosion of copper and brass in aqueous 1 M nitric acid was examined by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy and electrochemical frequency modulation techniques. The surface morphology was analyzed using scanning electron microscope and energy dispersive X-ray techniques. Potentiodynamic polarization curves indicated that the plant extract behaves as cathodic inhibitor. The results indicate that the extract solution of the plant could serve as an effective inhibitor for the corrosion of copper and brass in nitric acid media. As temperature increases, percentage of inhibition decreases. The degree of surface coverage of the adsorbed inhibitor was determined by weight-loss technique, and it was found that the results obeyed the Langmuir adsorption isotherm.     

Corrosion prevention of mild steel in acidic medium by 2-Pyrrolidin-1-yl-1,3-thiazole-5-carboxylic acid: Theoretical and experimental approach

The inhibition efficiency of 2-Pyrrolidin-1-yl-1,3-thiazole-5-carboxylic acid (PTCA) against mild steel (MS) corrosion was investigated in acidic solution by using quantum chemical calculations based on Density Functional Theory (DFT) method and electrochemical measurements. The electrochemical impedance spectroscopy (EIS), potentiodynamic, potential zero charge (pzc) analysis and electrochemical noise (EN) measurements at various concentrations (from 0.1 to 10 mM) and immersion times were utilized in experimental part. The surface analysis was achieved scanning electron microscope (SEM) and contact angle measurements in the absence and presence of 10 mM PTCA. According to DFT results, PTCA exhibited 3.737 eV band gap and 8.130 Debye dipole moment which were a signal of potentially convenient corrosion inhibitor properties. PTCA has a remarkable corrosion inhibition capability to mild steel, which inhibited both anodic and cathodic corrosion rates, relying on it's physically adsorption on the metal solution interface and protection ability was increased with increasing PTCA concentration. The obtained adsorption equilibrium constant was 11.11 × 10³ M^-1 and calculated standard free energy of adsorption was ?33.03 kJ mol^?1. The determined activation energy values were 55.58 kJ mol^?1 and 96.86 kJ mol^?1 in 0.5 M HCl in the absence and presence of 10 mM PTCA, respectively. PTCA demonstrated a strong inhibition efficiency of 98.3%, after 168 h immersion, according to the EIS results. As a consequently, we recommend that PTCA is a convenient inhibitor in 0.1 M HCl for mild steel protection against corrosion.     

On the corrosion inhibition of iron in hydrochloric acid solutions,Part I: Electrochemical DC and AC studies

The inhibitive action of 4-methyl pyrazole (4MP) against the corrosion of iron (99.9999%) in solutions of hydrochloric acid has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). At inhibitor concentration range (10^?3–10^?2 M) in 1.0 M acid, the results showed that 4MP suppressed mainly the anodic processes of iron corrosion in 1.0 M HCl by adsorption on the iron surface according to Temkin adsorption isotherm. Both potentiodynamic and EIS measurements reveal that 4MP inhibits the iron corrosion in 1.0 M HCl and that the efficiency increases with increasing inhibitor concentration. Data obtained from EIS were analyzed to model the corrosion inhibition process through an equivalent circuit.     

Influence of bis-(2-benzothiazolyl)-disulfide on corrosion inhibition of mild steel in hydrochloric acid media

The inhibiting behavior of bis-(2-benzothiazolyl)-disulfide on mild steel corrosion was evaluated in 1?M HCl solution. Weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques were used in this study. In EIS technique, by performing Kramers–Kronig transformations, the experimental results validated, before fitting any theoretical model on them. The obtained results showed that the inhibition efficiency (%IE) increases by increasing the concentration of bis-(2-benzothiazolyl)-disulfide up to 2.02?×??0^???M (%IE?～??2??8). Between the results obtained from various used techniques, a good agreement was found. Polarization curves indicate that the inhibition of the inhibitor is a mixed anodic–cathodic nature and Langmuir isotherm is found as an accurate isotherm describing the adsorption behavior. It also found that its inhibition mechanism of bis-(2-benzothiazolyl)-disulfide is at the interval of physical adsorption and chemical binding. The inhibition efficiency of the inhibitor decreased by rising of temperature in the range of 25??5?°C and these results, verified adsorption behavior of the inhibitor.     

Experimental study of inhibition of corrosion of mild steel in 1 M HCl solution by two newly synthesized calixarene derivatives

Inhibition of the corrosion of mild steel in molar hydrochloric acid by two calixarenes, including the effect of inhibitor concentration and temperature, has been investigated by use of weight loss and electrochemical measurements (polarisation and impedance). The results obtained showed that the rate of corrosion decreased substantially in the presence of the compounds, with maximum inhibition of 98.2 % by one of the compounds at a concentration of 10^?3 M. The effect of temperature on corrosion behaviour in the presence of different concentrations of the two new calixarenes was studied in the range 45–75 °C. The efficiency of inhibition by the compounds increased with increasing inhibitor concentration and was independent of temperature. Polarisation curves revealed that the calixarenes are mixed-type inhibitors. Adsorption of the inhibitors by the carbon steel surface obeyed the Langmuir adsorption isotherm. Some thermodynamic data for the dissolution and adsorption processes were also determined.     

Aqueous extract of <Emphasis Type="Italic">Argemone mexicana</Emphasis> roots for effective protection of mild steel in an HCl environment

The inhibition effect of aqueous Argemone mexicana root extract (AMRE) on mild steel corrosion in 1 M HCl has been studied by weight loss, Tafel polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy techniques. Results indicate that inhibition ability of AMRE increases with the increasing amount of the extract. A maximum corrosion inhibition of 94 % is acknowledged at the extract concentration of 400 mg L^?1. Polarization curves and impedance spectra reveal that both cathodic and anodic reactions are suppressed due to passive layer formation at the metal–acid interface. It is also confirmed by SEM micrographs and FTIR studies. Furthermore, the effects of acid concentration (1–5 M), immersion time (120 h) and temperature (30–60 °C) on inhibition potential of AMRE have been investigated by the weight loss method and electrochemical techniques. An adsorption mechanism is also proposed on the basis of weight loss results, which shows good agreement with the Langmuir isotherm.     

Stearate as a green corrosion inhibitor of magnesium alloy ZE41 in sulfate medium

The efficiency of stearate as a corrosion inhibitor for magnesium alloy ZE41 has been studied in sodium sulfate medium, employing electrochemical techniques like potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of polarization study imply that stearate functions as a mixed-type corrosion inhibitor with a predominant anodic control. The adsorption of stearate on alloy surface is found to obey the Langmuir adsorption isotherm. The proposed inhibition mechanism involved adsorption of stearate onto metal surface, followed by precipitation of magnesium stearate within the microdefects of Mg(OH)₂ surface film which enhanced the barrier effect of an otherwise porous partially protective film.     

Inhibition of mild steel corrosion in 5 % HCl solution by 5-(2-hydroxyphenyl)-1,2,4-triazole-3-thione

A new corrosion inhibitor, namely 5-(2-hydroxyphenyl)-1,2,4-triazole-3-thione (5-HTT), has been synthesized and its influence on corrosion inhibition of mild steel in 5 % HCl solution has been studied using weight loss method and electrochemical measurements. Potentiodynamic polarization measurements clearly reveal that the investigated inhibitor is of mixed type, and it inhibits the corrosion of the steel by blocking the active site of the metal. Changes in impedance parameters were indicative of adsorption of 5-HTT on the metal surface, leading to the formation of protective films. The degree of the surface coverage of the adsorbed inhibitors was determined by weight loss measurements, and it was found that the adsorption of these inhibitors on the mild steel surface obeys the Langmuir adsorption isotherm. The effect of the temperature on the corrosion behavior with addition of 5 × 10^?4 M of the inhibitor was studied in the temperature range 30–60 °C. The reactivity of this compound was analyzed through theoretical calculations based on density functional theory to explain the different efficiency of these compounds as a corrosion inhibitor.     

Inhibiting effects of 2-mercapto-1-methylimidazole on copper corrosion in 0.5 M sulfuric acid

The inhibiting efficiency of 2-mercapto-1-methylimidazole (MMI) on copper corrosion in sulfuric acid was investigated at 30 °C. Its effectiveness was assessed through electrochemical impedance spectroscopy, potentiodynamic polarization and gravimetric measurements. The results of study reveal that the inhibition efficiency of MMI depends on its concentration and attains approximately 81% at 10^?4 M. The inhibitor was adsorbed on the copper surface according the Langmuir adsorption isotherm model. The value of standard free energy of adsorption was calculated from this isotherm.     

Corrosion inhibition of steel in molar HCl by triphenyltin2–thiophene carboxylate

The effect of triphenyltin2–thiophene carboxylate (TTC) on the corrosion of steel in hydrochloric acid medium was studied using gravimetric, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor to reach 97% at 10^?3 M. Polarisation study shows that TTC is an efficient inhibitor and acts as a mixed-type inhibitor. EIS results indicate the increase of resistance transfer (R_T) and the decrease of double layer capacitance (C_dl) with TTC concentration. Triphenyltin2–thiophene carboxylate molecules lead to the formation of a protective layer on the surface of steel. The inhibitor is adsorbed on the steel surface according to Langmuir isotherm.     

Comparative inhibition study of mild steel corrosion in hydrochloric acid by new class synthesised quinoxaline derivatives: part I

7-Cchloro-3-(4-methoxystyryl)quinoxalin-2(1H)-one (CMOSQ) and 7-chloro-2-(4-methoxyphenyl)thieno(3.2-b)quinoxaline (CMOPTQ) have been investigated for mild steel corrosion in 1 M HCl at different concentrations using weight loss measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy methods. Generally, inhibition efficiency of the investigated compounds was found to depend on inhibitor concentration and their structures. Comparitive results showed that CMOPTQ was the best inhibitor and the inhibition efficiency increased with increasing the concentration and attained 86 and 87 % at 10^?3 M of CMOPTQ and 10^?3 M of CMOSQ, respectively. Potentiodynamic polarization studies clearly reveal that these inhibitors act essentially as cathodic-type inhibitors. The inhibition efficiency increases with immersion time and reaches 95 % CMOPTQ at 24 h. The electrochemical impedance spectroscopy result showed that these compounds act by formation of film.     

Influence of purine on copper behavior in neutral and alkaline sulfate solutions

The effect of purine (concentration range of 1.00 × 10^?6?C1.00 × 10^?2 M) on the behavior of copper in a 0.5 M Na₂SO₄ solution (pH 7 and pH 9) was studied using the open circuit potential measurement, potentiodynamic polarization, and chronoamperometry. Potentiodynamic polarization shows that purine acts as a copper corrosion inhibitor in both alkaline and neutral sulfate solutions. The efficiency of inhibition increases as the purine concentration increases. Chronoamperometric results follow the same trend as the results of potentiodynamic polarization. The inhibition effect can also be observed visually by microscopic examination of the electrode surface. Purine is adsorbed on copper surface according to the Langmuir adsorption isotherm.     

Hydroclathrus clathratus marine alga as a green inhibitor of acid corrosion of mild steel

The corrosion inhibitive and adsorption behaviors of Hydroclathrus clathratus on mild steel in 1 M HCl and 1 M H₂SO₄ solutions at 303, 313 and 323 K were investigated by weight loss, electrochemical, and surface analysis techniques. The results show that H. clathratus acts as an inhibitor of corrosion of mild steel in acid media. The inhibition efficiency was found to increase with increase in inhibitor concentration but to decrease with rise in temperature, suggestive of physical adsorption. The adsorption of the inhibitor onto the mild steel surface was found to follow the Temkin adsorption isotherm. The inhibition mechanism was further corroborated by the results obtained from electrochemical methods. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses supported the inhibitive action of the alga against acid corrosion of mild steel.     

Experimental and theoretical studies on protecting steel against 0.5 M H2SO4 corrosion by new schiff base

In this study, a novel green corrosion inhibitor called 2,2'-((1Z,1′Z)-((piperazine-1,4-diylbis(2,1-phenylene))bis(methanylylidene))bis(azanylylidene)) (PMA) has been tested against corrosion of carbon steel in 0.5 M H₂SO₄. Quantum and electrochemical methods were used to evaluate PMA's ability to inhibit the deterioration of carbon steel in an acidic environment. The results revealed that PMA acted as a mixed inhibitor, primarily anodic, whose inhibition action was enhanced by increasing its concentration. At 298.15 K, the maximum efficiency was around 91% with 1 × 10^?3 M PMA in 0.5 M H₂SO₄. The results showed that the inhibition occurred due to adsorption of the PMA molecules on the surface. The adsorbed layer of PMA satisfied the Langmuir adsorption isotherm. The morphology of the surface was examined using scanning electron microscopy.     

Electropolymerization of Mefenamic Acid on Copper and Copper Based Alloy as a New Strategy to Control the Release of Copper Ions from Copper Containing Devices

Poly-2-(2,3-dimethylanilino) benzoic acid (PMF) coatings on copper and brass alloy were synthesized by electrochemical oxidation of 2-(2,3-dimethylanilino) benzoic acid in the presence of oxalic acid as the reaction medium. Electrodeposition was carried out using the cyclic voltammetry technique using a silver/silver-chloride standard electrode, with a scan rate of 600 mV min^–1. Smooth and well adhered PMF coatings were electrosynthesized during sequential scanning of the potential in the range–500 mV to 1400 mV on copper and brass alloy. The electrodeposited coatings were characterized by recording the oxidation peaks at 122 mV for Cu and–0.7 mV for brass, in cyclic voltammetry and using scanning electron microscopy (SEM). Corrosion inhibition efficiency of coated copper and brass alloy was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The impedance results showed that the inhibition efficiency of coated copper is 89% and for coated brass 79.4% compared to the uncoated copper and brass in 0.1 M H₂SO₄.