Corrosion inhibition studies of copper in highly concentrated NaCl solutions

The influence of the concentration of sodium succinate (SS) on the corrosion and spontaneous dissolution of copper in aerated non-stirred highly concentrated (5.0 M) NaCl solutions was studied at different temperatures (10–60 °C). The investigations involved weight loss as well as potentiodynamic polarization and impedance measurements. The inhibition efficiency increases with increase in the concentration of SS and decreases with temperature. The inhibition mechanism involves adsorption of SS on the copper surface. An adherent layer of inhibitor is postulated to account for the protective effect. Energy dispersion X-ray (EDX) examinations of the electrode surface confirmed the existence of such an adsorbed film. The potential of zero charge (pzc) of copper was studied by the ac impedance technique and the mechanism of adsorption is discussed.     

A Corrosion Inhibition Study of a Novel Synthesized Gemini Nonionic Surfactant for Carbon Steel in 1 M HCl Solution

In this study, a gemini nonionic surfactant was synthesized as a corrosion inhibitor for carbon steel in 1 M HCl. Surface properties of the synthesized gemini nonionic surfactant were determined by using surface tension. The results showed that the gemini nonionic surfactant has good surface active properties. The corrosion inhibition effect of the synthesized inhibitor on carbon steel was evaluated by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss methods. The characterization of the film formed on the steel surface was carried out by scanning electron microscope (SEM) methods. The inhibitor molecules were adsorbed physically onto a carbon steel surface according to the Langmuir adsorption isotherm. The results revealed that the inhibitor acted as a mixed-type inhibitor. It was found that the inhibition efficiency increases with an increase in inhibitor concentration and decreases with increasing temperature. Thermodynamic parameters were calculated to elucidate the inhibitive mechanism.     

Phenothiazine as inhibitor of the corrosion of cadmium in acidic solutions

The corrosion of cadmium in 0.5m HClO4, CH3COOH or 0.25m H2SO4 in the absence and presence of small amounts of phenothiazine (10–6–10–4 m) as an inhibitor has been studied using both electrochemical impedance spectroscopy (EIS) and Tafel-plot techniques. Measurements were carried out at cathodic, open circuit and anodic potentials at different temperatures. In HClO4 and H2SO4 solutions the inhibition efficiency increases as both the concentration of phenothiazine and the temperature are increased. The effect of temperature in CH3COOH solution gives an opposite effect, that is, a decrease in the inhibition efficiency with increasing temperature. This behaviour is attributed to competitive adsorption between the inhibitor molecules and the acetate ions at the metal–solution interface. Phenothiazine can be considered as an inhibitor of mixed type with more pronounced effects in the anodic direction. The thermodynamic parameters in HClO4 containing the inhibitor were evaluated using the Bockris–Swinkels adsorption isotherm with n=4 as the configurational function. These parameters reveal that phenothiazine is adsorbed on the cadmium surface in molecular form with a strong interaction between the metal and the inhibitor.     

Inhibition by <Emphasis Type="Italic">Jasminum nudiflorum</Emphasis> 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.     

Aqueous extract of leaves of Morinda tinctoria as a corrosion inhibitor for aluminum in sulphuric acid medium

The corrosion inhibition of aluminum in sulphuric acid using an aqueous extract of leaves of Morinda tinctoria (MT) was studied with weight loss and electrochemical techniques. It was found that the MT extract acts as a good inhibitor for aluminum corrosion in the sulphuric acid medium. The inhibition efficiency of the inhibitor is found to increase with the increase in concentration of the acid. Synergistic effect increased the inhibition efficiency of MT in the presence of halide additives. The process of adsorption of the inhibitor on the metal surface is found to obey Freundlich isotherm. The adsorbed film on the metal surface has been analyzed by FT-IR and SEM-EDXS studies. Polarization measurements showed that MT extract is a mixed type inhibitor. Impedance results indicate adsorption of the MT on the Al surface is through charge transfer.     

Inhibition effect of methyl violet on the corrosion of cold rolled steel in 1.0 M sulfuric acid solution

The inhibition effect of methyl violet (MV) on the corrosion of cold rolled steel (CRS) in 1.0 M sulfuric acid (H₂SO₄) was investigated by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results show that MV is a good inhibitor, and inhibition efficiency increases with inhibitor concentration, while decreases with the temperature. The adsorption of MV on CRS surface obeys Langmuir adsorption isotherm equation. The thermodynamic parameters of adsorption enthalpy (ΔH°), adsorption free energy (ΔG°) and adsorption entropy (ΔS°) are calculated and discussed. Potentiodynamic polarization curves show that MV acts as a mixed-type inhibitor in sulfuric acid. EIS exhibits one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. Inhibition efficiency values obtained from weight loss, polarization and EIS are in reasonably good agreement. The adsorbed film on CRS surface containing optimum dose of MV was investigated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Depending on the results, the inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

Understanding the inhibitory effect of sodium oleate on the corrosion of Al and Al–Cu alloys in 1.0 M H<Subscript>3</Subscript>PO<Subscript>4</Subscript> solution—Polarization studies

Polarization measurements were employed, as a first step towards studying the corrosion behaviour of Al and two Al–Cu alloys, namely Al–4.5%Cu, and Al–7.5%Cu alloys in deaerated stirred 1.0 M H₃PO₄ solution at 25 °C. Inhibition of Al and Al–Cu alloys corrosion in 1.0 M H₃PO₄ solution, using sodium oleate (SO) as an anionic surfactant inhibitor, was also studied. Polarization curves showed that SO acted as a mixed-type inhibitor to Al corrosion, while it acted mainly as a cathodic inhibitor to the acid corrosion of Al–4.5%Cu, and Al–7.5%Cu alloys. Inhibition is accomplished by inhibitor adsorption on the electrode surface without detectable changes in the chemistry of corrosion. The relationship between surfactant concentration, surfactant critical micellar concentration (CMC), and corrosion inhibition is also discussed based on the Langmuir isotherm assumption, commonly applied in corrosion inhibition evaluations. The protection efficiency increases with increase in surfactant concentration and %Cu in Al samples. Maximum protection efficiency of the surfactant is observed at concentrations around its CMC. The mechanism of adsorption is discussed based on the surface charge of the electrode surface.     

Investigation of corrosion inhibitory effect of hydroxyl propyl alginate on mild steel in acidic media

The anti‐corrosion effect of hydroxyl propyl alginate (HPA) on mild steel in 1M HCl has been studied by chemical (weight loss) and electrochemical (polarization and electrochemical impedance spectroscopy) methods. From all the three methods, it is inferred that there is an increase in inhibition efficiency with increase in concentration of the inhibitor. Polarization studies revealed the mixed mode of inhibition by HPA. The mode of adsorption is physical in nature. The adsorption of HPA on mild steel followed Frumkin adsorption isotherm. The thermodynamic and kinetic parameters have been calculated and discussed. Surface morphological studies have been carried out with Scanning electron microscopy (SEM) and Atomic force microscopy (AFM). Fourier transform infrared spectroscopy (FTIR) is utilized to characterize the adsorbed film. SEM and AFM methods confirm the presence of inhibitor on the surface of the metal. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43004.     

Electrochemical characterization of the protective film formed by the unsymmetrical Schiff's base on the mild steel surface in acid media

The corrosion inhibition efficiency of a newly synthesized Schiff's base for the corrosion of mild steel was studied in 1.0 M HCl and 0.5 M H₂SO₄ solutions. The results of weight loss measurements, electrochemical impedance and potentiodynamic polarization measurements consistently demonstrated that the Schiff's base synthesized is a good corrosion inhibitor with an inhibitory efficiency of approximately 92% at an optimum inhibitor concentration of 600 mg/L. The inhibition in both of the corrosive media was observed to be a mixed type. The potential of zero charge (PZC) at the metal–solution interface was determined for both the inhibited and uninhibited solutions to provide the mechanism of inhibition. The inhibitor formed a film on the metal surface through chloride or sulfate bridges depending upon the medium. The temperature dependence of the corrosion rate was also studied in the temperature range from 27 to 50 °C. The value of the activation energy (E_a) calculated showed that the inhibition film formation on the metal surface occurred through chemisorption. The thermodynamic parameters such as the adsorption equilibrium constant (K_ads) and the free energy of adsorption (ΔG_ads) were calculated and discussed. Several adsorption isotherms were tested and the experimental data fit well with the Langmuir adsorption isotherm.     

3-Methyl-4-amino-5-mercapto-1,2,4-triazole as corrosion inhibitor for 6061 Al alloy in 0.5?M sodium hydroxide solution

3-Methyl-4-amino-5-mercapto-1,2,4-triazole (MAMT) was synthesized, and its inhibition action on the corrosion of 6061 Al alloy in 0.5 M sodium hydroxide was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The effect of inhibitor concentration, temperature, and concentration of the corrosion medium on the inhibitor action was investigated. The surface morphology of the metal surface was investigated by scanning electron microscopy (SEM). The inhibition efficiency increased with the increase in the concentration of the inhibitor, but decreased with the increase in temperature. Both thermodynamic and kinetic parameters were calculated and discussed. The adsorption of MAMT on the base alloy was found to be through physisorption, obeying Langmuir’s adsorption isotherm. The results obtained from both the techniques were in good agreement with each other.     

过期药呋塞米在醋酸溶液中对冷轧钢的缓蚀作用

通过电导率测量、pH测量、同步热分析(STA)、Tafel极化曲线法和电化学交流阻抗谱法研究了不同浓度和温度下过期药呋塞米在1 mol/L的醋酸溶液中对冷轧钢缓蚀作用。实验结果表明:过期药呋塞米在1 mol/L的醋酸溶液中对冷轧钢有较好的缓蚀效果,且缓蚀率随着缓蚀剂浓度和温度的增加而增大。该缓蚀剂在醋酸中对钢是一种抑制阴极和阳极的混合型缓蚀剂。缓蚀剂在冷轧钢表面的吸附符合Langmuir吸附等温式,其吸附是自发、物理吸附过程。同步热分析还说明了该缓蚀剂易稳定吸附在冷轧钢表面。     

The inhibition of low carbon steel corrosion in hydrochloric acid solutions by succinic acid: Part I. Weight loss, polarization, EIS, PZC, EDX and SEM studies

The effect of succinic acid (SA) on the corrosion inhibition of a low carbon steel (LCS) electrode has been investigated in aerated non-stirred 1.0 M HCl solutions in the pH range (2-8) at 25 °C. Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behaviour in the absence and presence of different concentrations of SA under the influence of various experimental conditions. Measurements of open circuit potential (OCP) as a function of time till steady-state potentials (E_st) were also established. Surface analysis using energy dispersive X-ray (EDX) and scanning electron microscope (SEM) allowed us to clarify the mechanistic aspects and evaluate the relative inhibition efficiency. Results obtained showed that SA is a good “green” inhibitor for LCS in HCl solutions. The polarization curves showed that SA behaves mainly as an anodic-type inhibitor. EDX and SEM observations of the electrode surface confirmed existence of a protective adsorbed film of the inhibitor on the electrode surface. The inhibition efficiency increases with increase in SA concentration, pH of solution and time of immersion. Maximum inhibition efficiency (≈97.5%) is obtained at SA concentrations >0.01 M at pH 8. The effect of SA concentration and pH on the potential of zero charge (PZC) of the LCS electrode in 1.0 M HCl solutions has been studied and the mechanism of adsorption is discussed. Results obtained from weight loss, polarization and impedance measurements are in good agreements.     

Evaluation of cysteine as environmentally friendly corrosion inhibitor for copper in neutral and acidic chloride solutions

The efficiency of cysteine as a non-toxic corrosion inhibitor for copper metal in 0.6 M NaCl and 1.0 M HCl has been investigated by electrochemical studies. Potentiodynamic polarization measurements and electrochemical impedance spectroscopy “EIS” were used to study the effect of cysteine on the corrosion inhibition of copper. Inhibition efficiency of about 84% could be achieved in chloride solutions. The presence of Cu²⁺ ions increases the inhibition efficiency to 90%. Potentiodynamic polarization measurements showed that the presence of cysteine in acidic and neutral chloride solutions affects mainly the cathodic process and decreases the corrosion current to a great extent and shifts the corrosion potential towards more negative values. The experimental impedance data were analyzed according to a proposed equivalent circuit model for the electrode/electrolyte interface. Results obtained from potentiodynamic polarization and impedance measurements are in good agreement. Adsorption of cysteine on the surface of Cu, in neutral and acidic chloride solutions, follows the Langmuir adsorption isotherm. The adsorption free energy of cysteine on Cu (−25 kJ mol⁻¹) reveals a strong physical adsorption of the inhibitor on the metal surface.     

Mitigation of corrosion of zinc with amylopectin: Electrochemical,adsorption, and surface studies

Carbohydrate polymers are proven to be potential green corrosion inhibitors because of their outstanding structural features and eco-friendliness. Work undertaken reflects the effectiveness of biopolymer amylopectin (AMP) as an eco-friendly green inhibitor to mitigate the deterioration of zinc in 0.1 M sulphamic acid (NH₂SO₃H). Electrochemical studies like potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were applied for corrosion rate measurement in the absence and presence of AMP. Thermodynamic and kinetic parameters were calculated and described in detail. The results were fitted into a suitable adsorption isotherm model, and an appropriate mechanism was proposed for the corrosion inhibition process. A detailed surface morphology study was done using scanning electron microscopy (SEM), electron-dispersive X-ray (EDX), and atomic force microscopy (AFM) techniques. The inhibition efficacy of AMP increased with an increase in its concentration and temperature. Upon the addition of the inhibitor, corrosion potential shifted more towards the positive side, indicating more control of the anodic process. The adsorption of AMP over zinc conformed to the Freundlich adsorption isotherm. For the concentration of 0.1 gL⁻¹, maximum corrosion inhibition efficiency of 74% could be accomplished. Surface studies reaffirmed the adsorption of AMP on the surface of the metal. Thus, AMP turned out to be an effective green inhibitor with economic benefits.     

Adsorption and inhibition effect of vanillin on cold rolled steel in 3.0 M H3PO4

The adsorption and inhibition effect of vanillin (4-hydroxy-3-methoxy-benzaldehyde) on cold rolled steel (CRS) in 3.0 M H₃PO₄ at 30–60 °C was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The results show that inhibition efficiency increases with the inhibitor concentration, while decreases with temperature. The adsorption of vanillin obeys Temkin adsorption isotherm. The thermodynamic parameters (adsorption enthalpy ΔH_ads, adsorption free energy ΔG_ads and adsorption entropy ΔS_ads) have been calculated and discussed in detail. Polarization curves show that vanillin acts as a mixed-type inhibitor. EIS shows that charge transfer resistance increases while the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The adsorbed film on CRS surface containing vanillin was examined by atomic force microscope (AFM). Quantum chemical calculation was applied to elucidate the adsorption mode of the inhibitor molecule onto steel surface. Depending on the results, the inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

Investigation of some oleochemicals as green inhibitors on mild steel corrosion in sulfuric acid

The inhibitive effect of four oleo chemicals (namely; 2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI)), regarded as green inhibitors, were studied for the corrosion protection of mild steel in 0.5 M H₂SO₄. The methods employed were weight loss, potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopy (SEM) was carried out on the inhibited and uninhibited metal samples to characterize the surface. The purity of synthesized inhibitors was checked by FT-IR and NMR studies. The inhibition efficiency increased with increase in inhibitor concentration, immersion time and decreased with increase in solution temperature. No significant change in IE values was observed with increase in acid concentration. The best performance was obtained for UDI possessing 96.2% inhibition efficiency at 500 ppm concentration. The adsorption of the compounds on the mild steel surface in the presence of sulfuric acid obeyed Langmuir’s adsorption isotherm. The values obtained for free energy of adsorption and heats of adsorption suggest physical adsorption. The addition of inhibitor decreased the entropy of activation suggesting that the inhibitors are more orderly arranged along the mild steel surface. The potentiodynamic polarization data indicate mixed control. The electrochemical impedance study further confirms the formation of a protective layer on the mild steel surface through the inhibitor adsorption.     

An experimental and theoretical investigation of adsorption characteristics of a Schiff base compound as corrosion inhibitor at mild steel/hydrochloric acid interface

This study investigates the effect of a Schiff base namely 2-[2-(2-(3-phenylallylidene)hydrazine carbonothioyl)hydrazinecarbonyl]benzoic acid (SB), on corrosion inhibition of mild steel in 1 M HCl. Electrochemical impedance measurement, potentiodynamic polarization and weight loss methods were applied to study adsorption of SB at metal/solution interface. Results revealed that SB is an excellent inhibitor for mild steel corrosion in 1 M HCl; showing a maximum efficiency 99.5% at concentration of 1.36 × 10⁻⁶ M. Fourier transform infrared spectroscopy (FTIR) observations of the mild steel surface confirmed the formation of protective film on the metal surface by studied compound. Polarization studies showed that SB is a mixed-type inhibitor. Adsorption process obeyed Langmuir’s model with a standard free energy of adsorption (∆G°_ads) of −46.7 kJ mol⁻¹. Energy gaps for interactions between mild steel surface and inhibitor were found to be close to each other showing that SB possess capacity to behave as both electron donor and acceptor.     

Synthesis and Inhibition Effect of a Novel Tri-cationic Surfactant on Carbon Steel Corrosion in 0.5 M H2SO4 Solution

A novel Tri-cationic surfactant was synthesized, purified and characterized. The critical micelle concentration value of the prepared surfactant was determined by surface tension and conductivity measurements. The surface parameters were calculated by surface tension measurements. The relationship between the surface properties and the corrosion inhibition efficiency of the prepared surfactant was discussed. The inhibition effect of the novel Tri-cationic surfactant on carbon steel corrosion in 0.5 M H₂SO₄ was studied by potentiodynamic polarization, electrochemical impedance spectroscopy and weight loss techniques. Potentiodynamic polarization studies revealed that the inhibitor acted as a mixed-type inhibitor. The high inhibition efficiency was attributed to the blocking of active sites on the steel surface through the adsorption of inhibitor molecules. Inhibitor adsorption on the carbon steel surface was in accordance with the Langmuir adsorption isotherm model. Thermodynamic adsorption and kinetic parameters were obtained from weight losses at different temperatures (20–60 °C).     

Amikacin disulfate: an aminoglycoside antibiotic drug as a corrosion inhibitor for copper in 1 M nitric acid medium

The effect of commercially available pharmaceutically active compound amikacin disulfate (AMK) against the corrosion of copper in 1 M HNO₃ solution was investigated using Tafel polarization, electrochemical impedance spectroscopy (EIS), and weight loss techniques. The results show that inhibition efficiency (IE %) increases with increasing inhibitor concentration from 0.1 to 1.0 mM. Increasing the temperature increased the corrosion rate, and results decreased the inhibition efficiency. The adsorption of inhibitor obeyed Langmuir adsorption isotherm model via physisorption mechanism. EIS technique exhibits one capacitive loop, indicating that the corrosion reaction is controlled by charge transfer process. Polarization measurements showed that the AMK is mixed-type inhibitor. The surface morphologies were studied by scanning electron microscopy and atomic force microscopic techniques. The corrosion mechanism were explained by Fourier transform infrared spectroscopy.     

Corrosion inhibition of aluminum with a 3‐(10‐sodium sulfonate decyloxy) aniline monomeric surfactant and its analog polymer in a 0.5M hydrochloric acid solution

The inhibitory effect of a 3‐(10‐sodium sulfonate decyloxy) aniline monomeric surfactant and the analog polymeric surfactant poly[3‐(decyloxy sulfonic acid) aniline] (PC₁₀) on the corrosion of aluminum in 0.5M hydrochloric acid was studied with weight loss and potentiodynamic polarization techniques. The results show that the inhibition occurred through the adsorption of inhibitor molecules on the metal surface. The inhibition efficiency was found to increase with increasing inhibitor concentration and decrease with increasing temperature. It was found that these inhibitors acted as mixed‐type inhibitors with anodic predominance. The adsorption of these compounds on the metal surface obeyed the Langmuir and Frumkin adsorption isotherms. Thermodynamic functions for both the dissolution and adsorption processes were determined. The obtained results from the weight loss and potentiodynamic polarization techniques were in a good agreement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011