INHIBITION OF THE CORROSION OF NICKEL AND ITS ALLOYS BY NATURAL CLOVE OIL

The corrosion behavior of nickel, Inconel 600, and Inconel 690 in different concentrations of HCl solutions and its inhibition by clove oil was studied using potentiostatic polarization measurements. As the acid concentration increases, the rate of corrosion increases, indicating that HCl accelerates the dissolution of nickel and its alloys. The inhibition efficiency of the clove oil was found to increase with increase of its concentration. The inhibitive action of this oil was discussed in view of adsorption onto the metal surface. The adsorbed layer acts as a barrier between the metal surface and aggressive solution, leading to a decrease in corrosion rate. The adsorption process follows Langmuir adsorption isotherms. It was found that the clove oil provides good protection to nickel and its alloys against pitting corrosion in chloride-containing solution using potentiodynamic anodic polarization techniques.     

The Inhibitory Effect and Adsorption Mechanism of Roasted Elaeis guineensis as Green Inhibitor on the Corrosion Processof Extruded AA6063 Al-Mg-Si Alloy in Simulated Solution

The green roasted Elaeis guineensis oil was tested as a natural inhibitor for Al-Mg-Si in simulated 3.5 % sodium chloride solution by linear potentiodynamic polarization and gravimetric method in the inhibited concentration variation between 5 % and 15 %. SEM/EDX studies were used to examine the surface morphology of the corrosion process and adsorption corrosion product that retards the degradation activities. From the experimental result, the adsorption of surface active compounds at the metal surface proved to create an organic protective film leading to efficient corrosion inhibition. The inhibitory effect significantly improved with about 98 % efficiency and the adsorption of Elaeis guineensis surfactants extract was found to follow the Langmuir adsorption isotherm.     

CHAMOMILE (Matricaria recutita) EXTRACT AS A CORROSION INHIBITOR FOR MILD STEEL IN HYDROCHLORIC ACID SOLUTION

The corrosion inhibition of mild steel in hydrochloric acid solution by chamomile (Matricaria recutita) extract (CE) was investigated through electrochemical (polarization, EIS) and surface analysis (optical microscopy/AFM/SEM) techniques. The effects of inhibitor concentration, temperature, and pH were evaluated. Thermodynamic parameters were calculated and adsorption studies were carried out. Finally, the surface morphology was investigated. The electrochemical studies showed that CE acts as a mixed-type corrosion inhibitor with predominantly anodic behavior. CE was adsorbed physically on the metal surface and obeyed the Langmuir adsorption isotherm. It impeded the corrosion processes by changing the activation energy. In the presence of CE, the metal surface was more uniform than the surface in the absence of inhibitor. Maximum inhibition efficiency (IE) was 93.28%, which was obtained at 22°C in 7.2 g/L of inhibitor in 1 M HCl solution.     

INHIBITION OF MILD STEEL CORROSION IN SULFURIC ACID MEDIUM BY HYDROXYETHYL CELLULOSE

The inhibitive effect of hydroxyethyl cellulose (HEC) on mild steel corrosion in aerated 0.5 M H₂SO₄ solution was studied using gravimetric and electrochemical techniques. The effect of temperature on corrosion and inhibition was also investigated. The results show that hydroxyethyl cellulose functioned as a good inhibitor in the studied environment and inhibition efficiency increased with concentration of inhibitor. Potentiodynamic polarization measurements revealed that HEC inhibited both the cathodic and anodic partial reactions of the corrosion processes. Impedance results clearly show that HEC inhibited the corrosion reaction by adsorption onto the metal/solution interface by significantly decreasing the double layer capacitance (C _dl ). This result was greatly pronounced in the presence of the inhibitor system (HEC + KI) that contains halide additive. Temperature studies revealed an increase in inhibition efficiency with rise in temperature. The adsorption behavior was found to obey the Freundlich isotherm. The values of activation energy, heat of adsorption, and standard free energy suggest that there was transition from physical to chemical adsorption mechanism of HEC on the mild steel surface. Quantum chemical calculations using the density functional theory (DFT) was employed to determine the relationship between molecular structure and inhibition efficiency.     

SURFACE ANALYSIS OF INHIBITOR FILMS FORMED BY N-(2-HYDROXYBENZILIDENE) THIOSEMICARBAZIDE ON CARBON STEEL IN ACIDIC MEDIA

The corrosion and behavior of carbon steel in 2 M HCl in the presence of N-(2-hydroxybenzilidene) thiosemicarbazide (HBTC) was investigated using weight loss and electrochemical studies. The morphology of carbon steel surface was investigated using scanning electron microscopy (SEM) and Mössbauer spectrometry. The corrosion current was determined using Tafel polarization. The inhibition efficiency increased with HBTC concentration; the experimental results suggest that the presence of HBTC in the solution increases the surface coverage (θ); a decrease in the corrosion spot with the increase of the HBTC concentration indicates good adsorbability of HBTC on the metal surface. The adsorption of this compound on the metal surface is found to obey Langmuir's adsorption isotherm. Mössbauer spectroscopy showed at this stage the main product of corrosion is a non-stoichiometric amorphous Fe³⁺ oxyhydroxide, consisting of a mixture of α, β, and γ-FeOOH, where γ-FeOOH is the main phase.     

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.     

INHIBITING EFFECT OF N-CYCLOHEXYL-N′-PHENYL THIOUREA ON THE CORROSION OF 304 SS IN HYDROCHLORIC ACID SOLUTION

The inhibiting action of N-cyclohexyl-N′-phenyl thiourea (CPTU) on the corrosion behavior of 304 SS in 3 M hydrochloric acid solution has been investigated using potentiodynamic polarization technique at four different temperatures. The results obtained reveal that CPTU acts as an efficient anodic inhibitor for the corrosion of 304 SS. Good inhibition efficiency (>92%) was evident in the acidic solution, and it was found to vary with temperature and concentration of the inhibitor. The adsorption of this compound on the 304 SS surface was found to obey the Temkin adsorption isotherm, and the inhibition was governed by physical adsorption mechanism. The thermodynamic parameters of adsorption deduced revealed a strong interaction and spontaneous adsorption of CPTU on the steel surface. Scanning electron microscopic study (SEM) was done to investigate the surface characterization of inhibited and uninhibited 304 SS specimens.     

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   

CORROSION INHIBITION OF CuNi10Fe ALLOY WITH PHENOLIC ACIDS

The purpose of this study was to investigate the efficiency of two phenolic acids, namely p-hydroxybenzoic acid (HBA) and protocatechuic acid (PCA), as corrosion inhibitors for CuNi10Fe alloy in a 0.5 mol dm^?3 NaCl solution. In these investigations, open circuit potential measurements, potentiodynamic polarization measurements, and the linear polarization method have been used. It was found that both phenolic acids had similar corrosion inhibition effects on the CuNi10Fe alloy dissolution. The inhibition efficiency (IE) increased with increase in inhibitor concentration. The polarization shows that both compounds functioned as cathodic corrosion inhibitors by adsorption on the surface of CuNi10Fe alloy according to the Freundlich adsorption isotherm. The numerical values of free energies of adsorption indicate physical adsorption of the compounds on the electrode surface. DFT-based quantum chemical computations and molecular dynamics (MD) simulations revealed identical electronic and adsorption structures for both HBA and PCA, which could account for the similarities in the experimentally observed inhibiting effects.     

Inhibiting Effect of Ionic Liquids on the Corrosion of Mild Steel in H2S and HCl Solution

Four imidazolium-based ionic liquids (ILs) were selected to investigate the inhibiting effect of ILs with various alkyl chain lengths on the corrosion of mild steel in H₂S and HCl solution using electrochemical experiments, weight loss and surface analyses, and quantum chemical study. The results demonstrated that these ILs acted as mixed-type inhibitors and efficiently inhibited the corrosion of mild steel in H₂S and HCl solution. Their excellent corrosion inhibition ability was due to their adsorption process on the metal surface, which followed the Langmuir adsorption isotherm. Furthermore, extending the alkyl chain length in the ILs could improve their inhibition performance.     

6种燕尾形苝二酰亚胺类双子表面活性剂对碱性锌电极缓蚀机理理论研究

为了研究燕尾型苝二酰亚胺类双子表面活性剂对碱性锌电极缓蚀机理,利用密度泛函理论（DFT）和分子动力学模拟（MD）方法,探讨了两类共6种燕尾型苝二酰亚胺类双子表面活性剂的吸附行为。DFT计算结果表明,前线分子轨道分布主要位于分子核心的苝二酰亚胺骨架上,且苝二酰亚胺骨架上的N原子为分子的反应活性中心。分子动力学模拟表明,6种燕尾型苝二酰亚胺类双子表面活性剂均能与水溶液中的金属锌表面发生相互作用,N₂、P₂在两类双子表面活性剂中均表现出有较高的吸附能和较大的扩散系数,吸附能分别为-11315.868 kcal/mol、-10785.698 kcal/mol,扩散系数分别为2.5、1.32;研究结果同时表明,N₂和P₂形成的双子表面活剂膜层对腐蚀粒子OH^-的阻止效果较好,能够在金属锌表面起到很好的缓蚀效果。     

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.     

磷对锌-镍合金耐蚀性的影响

以次磷酸钠为磷元素来源,研究了磷对锌-镍合金的电化学过程、成分、表面形貌和耐蚀性的影响。实验发现:磷需要在镍表面的催化作用下才能析出,镍和磷的沉积过程属于协同效应。磷的质量分数提高,有利于增大锌-镍合金中镍的质量分数,改善锌-镍合金的耐蚀性。然而,次磷酸钠过量会使得镀液的稳定性下降,锌-镍合金表面疏松、发黑,耐蚀性变差。     

Corrosion inhibition of mild steel in acidic media by Basic yellow 13 dye

The inhibition performance of Basic yellow 13 dye on mild-steel corrosion in hydrochloric acid solution was studied at 25 °C using weight loss and electrochemical techniques. The effect of inhibitor concentration on inhibition efficiency has been studied. Inhibition efficiency increased with increase of Basic yellow 13 concentration. The results showed that this inhibitor had good corrosion inhibition even at low concentrations (95% for 0.005 M Basic yellow 13) and its adsorption on mild-steel surface obeys Langmuir isotherm. ΔG _ads was calculated and its negative value indicated spontaneous adsorption of the Basic yellow 13 molecules on the mild-steel surface and strong interaction between inhibitor molecules and metal surface. The value of ΔG _ads was less than 40 kJmol⁻¹, indicating electrostatic interaction between the charged inhibitor molecules and the charged metal surface, i.e., physical adsorption.     

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.     

盐酸介质中头孢硫脒对碳钢的缓蚀作用

采用动电位极化曲线和交流阻抗实验,研究了抗生素——头孢硫脒的缓蚀剂在盐酸介质中对碳钢的缓蚀性能和缓蚀作用机理。结果表明,头孢硫脒对碳钢在1.0 mol/L盐酸溶液中具有良好的缓蚀性能,当头孢硫脒浓度为0.4 mmol/L时,缓蚀率达86%以上,为抑制阴极反应为主的混合型缓蚀剂。头孢硫脒在碳钢表面的吸附符合Langmuir等温式,属于单分子层吸附,其吸附行为是以化学吸附为主的物理和化学混合吸附。     

Effects of different nitrogen doses on thymoquinone and fatty acid composition in seed oil of black cumin (Nigella sativa L.)

Black cumin, Nigella sativa L. belonging to Ranunculaceae, is a valuable medicinal plant because of the curative effects of seed and oil. Despite studies on black cumin, there are few studies on the effects of nitrogen on fatty acid composition, no records on thymoquinone yield, and the thymoquinone content of the seed oil. In this study, the effects of different nitrogen doses on the seed oil yield, thymoquinone ratio/yield, and fatty acid compositions were investigated. Field studies with nitrogen doses (0, 40, 60, 80, and 100 kg/ha) were studied using the randomized plot design. As a result of the research, nitrogen doses significantly affected the oil and thymoquinone yields while insignificant on the thymoquinone ratio. The highest oil yield with 501.6 kg/ha was obtained from 80 kg/ha of the nitrogen doses, while the highest thymoquinone yield with 10.24 kg/ha was obtained from the control plots. Thymoquinone yields were in the same statistical group with other nitrogen doses, except for means of 100 kg/ha nitrogen doses. Linoleic, oleic, and palmitic acids were major fatty acids of black cumin, and their variations were insignificant in nitrogen applications. The values of butyric, capric, and linolenic acids varied significantly in different nitrogen doses. As a result of the study, it was determined that the highest oil yield was obtained from 80 kg/ha nitrogen application. It has been determined that nitrogen doses above 60–80 kg/ha should be avoided for the seed oil and thymoquinone yields in black cumin.     

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.     

Novel Gemini Cationic Surfactants: Thermodynamic,Antimicrobial Susceptibility,and Corrosion Inhibition Behavior against Acidithiobacillus ferrooxidans

The Egyptian oil and gas industry is suffering from severe metal corrosion problems, particularly microbial-induced corrosion. There is limited knowledge on the corrosion inhibition of carbon steels in the presence of an acidophilic, iron-oxidizing bacterial species Acidithiobacillus ferrooxidans. Therefore, in this study, novel Gemini cationic surfactants, in three forms depending on variation in alkyl chains of 8, 12, and 16 carbon atoms named FHPAO, FHPAD, and FHPAH, respectively, were synthesized and characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopy. The surface parameters and the thermodynamic of the synthesized surfactants were evaluated at three different temperatures, 20, 40, and 60 °C. The synthesized Gemini cationic surfactants were tested as broad-spectrum antimicrobial, antibacterial and anticandida agents. They evaluated as biocides and corrosion inhibitors against Acidithiobacillus ferrooxidans. FHPAD showed higher adsorption ability at the solution interface and higher affinity to construct micelles than FHPAO and FHPAH. Both adsorption and micellization processes were hydrophobic and temperature dependent. FHPAO, FHPAD and FHPAH exhibited wide-spectrum antimicrobial activities, and the highest activity and the lowest minimum bactericidal/fungicidal inhibitory concentrations were attributed to FHPAD. Furthermore, synthesized FHPAD demonstrated the highest metal corrosion inhibition efficiency of 95.5% at 5 mM in comparison to 87.5% and 81.7% for FHPAO and FHPAH, respectively. In conclusion, this study provides novel synthesized cationic surfactants with many applications in the oil and gas industry, such as broad-spectrum antimicrobial, biocides, and corrosion inhibitors for acidophilic, iron-oxidizing bacterial species Acidithiobacillus ferrooxidans.     

盐酸介质中Tw-20与聚丙烯酸对铁腐蚀的协同缓蚀作用

运用稳态极化曲线、电化学阻抗谱和恒电位方波测极化阻力 (Rp)等电化学测试方法 ,研究了 0 .5mol·L-1HCl介质中非离子表面活性剂吐温 - 2 0 (Tw - 2 0 )在铁表面的吸附特征及其与聚丙烯酸 (PAAC)对铁腐蚀的协同缓蚀作用 ,证明Tw - 2 0在铁表面的吸附遵循修正的Langmuir吸附等温式 ,探讨了铁 /盐酸体系中Tw - 2 0与PAAC协同缓蚀作用的特点和机理