Computational and electrochemical investigation for corrosion inhibition of nickel in molar nitric acid by piperidines

The adsorption and corrosion inhibition behaviour of four selected piperidine derivatives, namely piperidine (pip), 2-methylpiperidine (2mp), 3-methylpiperidine (3mp), and 4-methylpiperidine (4mp) at nickel in 1.0 M HNO₃ solution were studied computationally by the molecular dynamics simulation and quantum chemical calculations and electrochemically by Tafel and impedance methods. The results indicate a strong dependence of the inhibition performance on the nature of the metal surface, in addition to the structural effects of piperidines. Inhibition is accomplished by adsorption of piperidines on the metal surface without detectable changes in the chemistry of corrosion. Adsorption is predominantly chemisorptive in the active region and by hydrogen bond formation in the passive region. The potential of zero charge (PZC) of the nickel electrode was determined in 1.0 M HNO₃ solutions in the absence and presence of 10⁻² M 2mp, and the electrostatic (physical) adsorption was discussed. The inhibition efficiency of these compounds increases in the order: 4mp > 3mp > 2mp > pip. Molecular simulation studies were applied to optimize the adsorption structures of piperidine derivatives. The nickel/inhibitor/solvent interfaces were simulated and the charges on the inhibitor molecules as well as their structural parameters were calculated in the presence of solvent effects. Quantum chemical calculations based on the ab initio method were performed to determine the relationship between the molecular structure of piperidines and their inhibition efficiency. Results obtained from Tafel and impedance methods are in good agreement and confirm theoretical studies.     

噻二唑衍生物分子结构与其缓蚀性能的关系

利用交流阻、Tafel极化曲线和原子力显微镜（AFM）,研究2-氨基-1,3,4-噻二唑（ATD）、5-甲基-2-氨基-1,3,4-噻二唑（MATD）、5-苯基-2-氨基-1,3,4-噻二唑（PATD）和2,5-二苯基-1,3,4-噻二唑（DPTD）4种具有不同取代基的噻二唑衍生物在50 mg·L^-1硫溶液中对金属银的缓蚀性能。实验结果表明：缓蚀剂成功地吸附到了金属表面,金属腐蚀受到明显的抑制,且4种缓蚀剂的缓蚀效率的大小顺序是：MATD>PATD>ATD>DPTD。位于噻二唑环2,5位置上非极性和极性基团结构的变化,极性基团均对缓蚀剂的缓蚀性能有较大影响。因极性基团更容易吸附到金属表面,所以当噻二唑环上存在极性基团时,其抗腐蚀性能明显增强;当环上存在非极性基团时,与芳基相比,非极性基团为烷基时,其缓蚀性能更好,原因可能是由于芳基的体积较大,在吸附过程中受到的阻力较大。通过动力学分析可知：4种缓蚀剂在金属表面的吸附遵循Langmuir吸附等温方程,吸附类型属于化学吸附为主的混合吸附。通过分子动力学模拟,进一步研究了4种缓蚀剂的抗腐蚀机理,结果表明缓蚀剂与金属界面发生吸附时,4种缓蚀剂的噻二唑环和环上亲水支链中的极性基团优先吸附到金属银表面,理论计算和实验结果一致。     

ac impedance, X-ray photoelectron spectroscopy and density functional theory studies of 3,5-bis(n-pyridyl)-1,2,4-oxadiazoles as efficient corrosion inhibitors for carbon steel surface in hydrochloric acid solution

The corrosion inhibition properties of a new class of oxadiazole derivatives, namely 3,5-bis(n-pyridyl)-1,2,4-oxadiazoles (n-DPOX) for C38 carbon steel corrosion in 1 M HCl medium were analysed by electrochemical impedance spectroscopy (EIS). An adequate structural model of the interface was used and the values of the corresponding parameters were calculated and discussed. The experimental results showed that these compounds are excellent inhibitors for the C38 steel corrosion in acid solution and that the protection efficiency increased with increasing the inhibitors concentration. Electrochemical impedance data demonstrate that the addition of the n-DPOX derivatives in the corrosive solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of an adsorbed layer over the steel surface. Adsorption of these inhibitors on the steel surface obeys to the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy (XPS) and the thermodynamic data of adsorption showed that inhibition of steel corrosion in normal hydrochloric solution by n-DPOX is due to the formation of a chemisorbed film on the steel surface. Quantum chemical calculations using the Density Functional Theory (DFT) and the Quantitative Structure Activity Relationship (QSAR) approach were performed on n-DPOX derivatives to determine the relationship between molecular structure and their inhibition efficiencies. The results of the quantum chemical calculations and experimental inhibition efficiency were subjected to correlation analysis and indicate that their inhibition effect is closely related to E_HOMO, E_LUMO, and dipole moment (μ).     

Experimental and quantum chemical studies of the effect of poly ethylene glycol as corrosion inhibitors of aluminum surface

The corrosion inhibition of poly ethylene glycol (PEG) toward the aluminum surface in 1.0 M HCl has been studied by weight loss and polarization techniques. The results showed that the PEG acts as a good inhibitor and the inhibition efficiency is due to the anodic and cathodic inhibition (mixed type). The thermodynamic functions were calculated to find a good correlation with the inhibition efficiency. Quantum chemical parameters were calculated using ab initio and DFT methods to find a good correlation with the inhibition efficiency. A good correlation was found between the theoretical calculations and experimental observations.     

Experimental and theoretical study of the effect of some heterocyclic compounds on the corrosion of low carbon steel in 3.5% NaCl medium

The efficiency of three heterocyclic compounds, 3-amino-1,2,4-triazole, 4-hydroxy-2H-1-benzopyran-2-one and 4-hydroxy-3-(1H-1,2,4-triazole-3-ylazo)-2H-1-benzopyran-2-one (abbreviated 3-ATA, 4-HQ and 3-ATA-Q, respectively) as steel corrosion inhibitors in 3.5% NaCl has been investigated by Tafel extrapolation and linear polarization methods. Corrosion parameters and adsorption isotherms were determined from current-potential curves. It was found that inhibition efficiencies (η%) and surface coverage (θ) increase with an increase in the concentration of 3-ATA and 3-ATA-Q. However, 4-HQ accelerates the corrosion rate as its concentration increases. The adsorption of 3-ATA and 3-ATA-Q on the steel surface obey Langmuir isotherm. A clear correlation was found between corrosion inhibition efficiency and theoretical parameters obtained by the density functional B3LYP/6-31g(d) method. The experimental results are supported by the theoretical data.     

Copper corrosion inhibitors in near neutral media

The efficiency of nontoxic imidazole derivatives as copper corrosion inhibitors in sodium chloride solutions was studied by electrochemical polarization methods (Tafel extrapolation and polarization resistance method) and weight-loss measurements. Results obtained during this study show that inhibitors with higher molecular weight, especially those with a phenyl ring, have better inhibiting properties. The values of free energy of adsorption, as calculated from Freundlich isotherm, indicate that investigated imidazole derivatives physisorbe on the copper surface.     

Chromenes as efficient corrosion inhibitor for mild steel in HCl solution

The Chromene derivatives having heteroatoms as active sites were investigated for scaling downthe corrosion process in mild steel (MS). The effectiveness of the inhibitors was monitored by gravimetric potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. Observations suggested that the mechanism of inhibition is mainly due to the adsorption of the inhibitor molecules on the MS surface. Adsorption of both inhibitors follows the Langmuir adsorption isotherm. Tafel curve shows that both inhibitors act as mixed type inhibitor. Morphological studies were done by FESEM and AFM instruments. These images indicated the formation of a protective layer on the MS surface which slows down the process of corrosion. DFT calculation provides the valuable quantum chemical parameters for both inhibitors which are supportive of the results obtained from gravimetric and EIS methods.     

Humic Acid from Livestock Dung: Ecofriendly Corrosion Inhibitor for 3SR Aluminum Alloy in Alkaline Medium

Humic acids (HAs) extracted from cow, goat, and poultry dung were studied. Extraction was performed by treating the source materials with acid hydrolysis using hydrochloric acid (HCl) before alkaline extraction with sodium hydroxide (NaOH). Yields of 3.33, 2.67, and 1.28% dry weight were obtained from cow, goat, and poultry dung respectively. The extracted humic acids were characterized using Fourier transform-infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopy techniques. The results obtained were in good agreement with commercial HA (Sigma-Aldrich). The humic acid extracted from cow dung was used to evaluate its corrosion inhibition potential for alkaline-induced corrosion of 3SR aluminum alloy using weight loss and electrochemical (potentiodynamic polarization) techniques at 30°–60°C. Results obtained show that the humic acid functions as an excellent corrosion inhibitor for aluminum alloy in 0.1 M NaOH solution. Corrosion inhibition efficiency increased with increase in humic acid concentration but decreased with rise in temperature. Results from potentiodynamic polarization measurements show that the HA behaved mostly as a mixed-type inhibitor. Adsorption of the humic acid was found to obey the Langmuir adsorption isotherm at all concentrations and temperatures studied. The mechanism of physical adsorption has been proposed based on the trend of inhibition efficiency with temperature. The proposed mechanism was also corroborated by kinetic and thermodynamic parameters obtained.     

Experimental and computational investigations of corrosion and corrosion inhibition of iron in acid solutions

The corrosion inhibition of iron in 1.0 M HNO₃ by some benzimidazole derivatives, namely 2-(aminomethyl)benzimidazole, 2-(chloromethyl)benzimidazole, and 2-(methylthio)benzimidazole has been studied using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results showed that the inhibition efficiency increased with the increase of benzimidazole derivatives concentration and the higher inhibition efficiency is obtained for 2-(aminomethyl)benzimidazole. Quantum chemical calculations and molecular dynamics (MD) simulations were used to evaluate the structural, electronic, and reactivity parameters of the selected benzimidazole derivatives. The MD method has also been used to simulate the adsorption of the selected benzimidazole derivatives and solvent ions on the iron surface.     

长链烷基咪唑作用下铝箔的腐蚀行为

研究了长链烷基咪唑缓蚀剂在铝箔腐蚀中的作用。结果表明,温度、盐酸浓度和长链烷基咪唑浓度对铝箔腐蚀有重要的影响。随盐酸浓度加大,腐蚀速率逐步加大;发现离子液体浓度较小时,缓蚀效率变化明显。高温时长链烷基咪唑仍呈现出良好的缓蚀性能。对腐蚀作用机制进行了初步探讨。     

Piperazine derivatives as inhibitors of the corrosion of mild steel in 3.9 M HCl

The inhibitory action of two piperazine derivatives, 1-benzyl piperazine (P1) and bis(1-benzylpiperazine) thiuram disulfide (P2) on the corrosion of mild steel in 3.9 M HCl at different concentrations has been investigated in the temperature domain 298–333 K. Both weight loss measurements and potentiodynamic polarization methods showed that P2 was the best inhibitor and that its inhibition efficiency increased with concentration to a value >92% at 10⁻³ M. Potentiodynamic polarization studies clearly revealed that P2 acts as cathodic-type inhibitor. The activation energy for the corrosion rates was evaluated in the temperature range 298–333 K. Adsorption of P2 on the mild steel surface in 3.9 M HCl followed a Langmuir isotherm model. A physical adsorption phenomenon is proposed.     

月桂基咪唑啉对Q235钢的缓蚀吸附作用

采用失重法和电化学方法研究了月桂基咪唑啉（IM-11）、1-氨乙基-2-月桂基咪唑啉（AIM-11）和1-羟乙基-2-月桂基咪唑啉（HIM-11）三种化合物在CO₂饱和的3%NaCl溶液中对Q235钢的缓蚀性能,探讨了其在Q235钢表面的吸附行为。结果显示,3种化合物均具有较好的抗相似文献   

Plant derived cationic dye as an effective corrosion inhibitor for 7075 aluminum alloy in 3.5% NaCl solution

The inhibition of the corrosion of 7075 aluminum alloy in 3.5 wt.% NaCl solution by 5,6-dihydro-9,10-dimethoxybenzo[g]-1,3-benzodioxolo[5,6-a]quinolizinium (berberine) has been studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM). Inhibition efficiency was found to increase with increasing concentration of berberine. The adsorption of the berberine on the 7075 aluminum alloy surface obeyed the Langmuir adsorption isotherm. The adsorbed film on 7075 aluminum alloy surface containing inhibitor was confirmed by the SEM, and SECM. The results obtained showed that the berberine could serve as an effective inhibitor of the corrosion of 7075 aluminum alloy in 3.5% NaCl.     

Synergistic inhibition between the gemini surfactant and bromide ion for steel corrosion in sulphuric acid

The inhibitive synergistic effect between a cationic gemini surfactant, 1,3-propane-bis(dimethyl dodecylammonium bromide) (12-3-12), and bromide ion for the corrosion inhibition of cold rolled steel in 0.5 mol L⁻¹ H₂SO₄ was investigated by weight loss, potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The inhibition system composed by 12-3-12 and bromide ion is efficient. The adsorption mechanism of the 12-3-12 and bromide ion on steel in acidic medium is discussed on the basis of experimental data and an adsorption model is proposed. Adsorption of inhibitor system on the mild steel surface in acidic medium obeys Langmuir’s adsorption isotherm. In addition, potentiodynamic polarization studies show that the system acts as a mixed-type inhibitor. Electrochemical impedance spectroscopy also suggests the formation of a protective layer on the steel surface by the adsorption of surfactant molecules and bromide ions.     

Protection of copper surface in acidic chloride solution by non-toxic thiadiazole derivative

This paper deals with electrochemical properties of copper in the presence of the non-toxic compound 2-amino- 5-ethyl- 1,3,4-thiadiazole (AETDA) in acidic chloride solution. Electrochemical techniques: open circuit potential measurements, linear potentiodynamic measurements, cyclic voltammetry measurements and chronoamperometric measurements in addition to SEM–EDS analysis were used during the work. Results show that inhibition efficiency of 2-amino-5-ethyl-1,3,4-thiadiazole depends on inhibitor concentration and immersion time of copper electrode in inhibitor solution. Cyclic voltammetry and linear potentiodynamic measurements beside chronoamperometric measurements indicate formation of protective layer on copper surface. Moreover, results obtained by electrochemical measurements point out that the stability of formed layer depends primarily on the concentration of inhibitor and of potential values at which protective film is formed. Also, potentiodynamic measurements show that AETDA in acidic chloride solutions acts as mixed-type inhibitor. Inhibition mechanism of 2-amino-5-ethyl-1,3,4-thiadiazole includes adsorption of inhibitor on active sites on electrode surface which was confirmed by SEM–EDS analysis of the electrode surface. Adsorption of the AETDA in HCl solution obeys Langmuir adsorption isotherm.     

Electrochemical behavior of nickel in nitric acid and its corrosion inhibition using some thiosemicarbazone derivatives

The adsorption and corrosion inhibition behavior of three selected thiosemicarbazone derivatives, namely 3-pyridinecarboxaldehyde thiosemicarbazone (META), isonicotinaldehyde thiosemicarbazone (PARA) and 2-pyridinecarboxaldehyde thiosemicarbazone (ORTHO) at the nickel surface were studied electrochemically by Tafel and impedance methods and computationally by carrying out Monte Carlo searches of configurational space on nickel/thiosemicarbazone derivative system. Electrochemical measurements showed that the inhibition efficiency of these compounds increased with increase in their concentration. The recorded inhibition efficiencies of the three tested thiosemicarbazone increase in the order: META > PARA > ORTHO. Polarization studies showed that these compounds act as mixed-type inhibitors for nickel corrosion in 1.0 M HNO₃ solutions. Results obtained from Tafel and impedance methods are in good agreement. Thiosemicarbazone derivatives have been simulated as adsorbate on Ni (1 1 1) substrate and the adsorption energy, binding energy and the low energy adsorption sites have been identified on nickel surface.     

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.     

Surface protection of copper in acid medium by azoles and surfactants

The influence of derivatives of 1,2,4 triazole, 3-amino 1,2,4-traizole (ATA), 3-amino 5-mercapto 1,2,4 triazole (AMT) and 3-amino 5-methylthio 1,2,4 triazole (AMTT) and ionic surfactants cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) on the corrosion control of copper in acidic solution was investigated by gravimetric and electrochemical methods. The combined effect of triazoles and surfactants was also evaluated. Electrochemical parameters like corrosion potentials corrosion current density, corrosion rates and inhibition efficiencies were determined. The results reveal the fact that of all triazoles AMTT shows best inhibition and anionic surfactant SDS protects the surface better than the cationic surfactant CTAB. The polarisation data reveal that all inhibitors behave as a mixed type inhibitor. Adsorption of these inhibitors on the surface of copper is found to obey the Langmuir adsorption isotherm. A marked inhibition synergism effect is shown by all the combinations of triazole and surfactant.     

Corrosion inhibition of carbon steel in hydrochloric acid by furan derivatives

The efficiency of three furan derivatives (2-methylfuran, furfuryl alcohol and furfurylamine), as corrosion inhibitors for carbon steel in 1 M HCl, has been determined by gravimetric and electrochemical measurements. These compounds inhibit corrosion even at very low concentrations, and furfuryl alcohol is the best inhibitor. Polarization curves indicate that all compounds are mixed inhibitors, affecting both cathodic and anodic corrosion currents. Adsorption of furan derivatives on the carbon steel surface is in agreement with the Langmuir adsorption isotherm model, and the calculated Gibbs free energy values confirm the chemical nature of the adsorption. The structural and electronic properties of these inhibitors, obtained using AM1, PM3, MNDO and MINDO/3 semi-empirical self-consistence field methods, are correlated with their experimental efficiencies.     

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.