Investigation on the inhibition effect of aspartic acid and Zn2+ ions on carbon steel surface in aqueous solution

A protective film has been formed on the surface of carbon steel in aqueous environment using a synergistic mixture of an environment-friendly inhibitor, aspartic acid, and Zn²⁺. The synergistic effect of aspartic acid (AS) in controlling corrosion of carbon steel has been investigated by gravimetric studies in the presence of Zn²⁺. The formulation consisting of AS and Zn²⁺ has an excellent inhibition efficiency. The results of potentiodynamic polarization revealed that the formulations are of mixed-type inhibitor. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous environment. X-ray photoelectron spectroscopic analysis of the protective film showed the presence of the elements iron, nitrogen, oxygen, carbon, and zinc. The spectra of these elements in the surface film showed the presence of oxides/hydroxides of iron(III), Zn(OH)₂, and [Fe(III)/Fe(II)–Zn(II)-AS] complex. Further, surface characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy are used to ascertain the nature of the protective film formed on the carbon steel surface.     

SYNERGISTIC EFFECT OF N,N-BIS(PHOSPHONOMETHYL) GLYCINE AND ZINC IONS IN CORROSION CONTROL OF CARBON STEEL IN COOLING WATER SYSTEMS

A protective film has been developed on the surface of carbon steel in low chloride aqueous environment using a synergistic mixture of an environmentally friendly phosphonic acid, N,N-bis(phosphonomethyl) glycine (BPMG), and zinc ions. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the chosen environment. Potentiodynamic polarization studies showed that the inhibitor is a mixed inhibitor. X-ray photoelectron spectroscopic analysis (XPS) of the film showed the presence of the elements iron, phosphorus, nitrogen, oxygen, carbon, and zinc. Deconvolution spectra of these elements in the surface film showed the presence of oxides/hydroxides of iron(III), Zn(OH)₂, and [Zn(II)-BPMG] complex. This inference is further supported by the reflection absorption Fourier transform infrared spectrum of the surface film. Analysis by SEM is presented for both the corroded and protected metal surfaces. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.     

CORROSION INHIBITION OF CARBON STEEL IN LOW CHLORIDE MEDIA BY AN AQUEOUS EXTRACT OF HIBISCUS ROSA-SINENSIS LINN

The inhibition efficiency (IE) of an aqueous extract of white flower, namely, Hibiscus rosa-sinensis Linn., in controlling corrosion of carbon steel immersed in an aqueous solution containing 60 ppm of Cl^-has been evaluated by the mass loss method. The flower extract (FE) shows good IE. In the presence of Zn²⁺, excellent IE is shown by the flower extract. A synergistic effect exists between the flower extract and Zn²⁺. The mechanistic aspects of corrosion inhibition have been investigated by polarization study and AC impedance spectra. Polarization study reveals that the formulation consisting of flower extract and Zn²⁺ functions as a mixed inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. The active principle in the flower extract is quercetin-3-O-glucoside. This has been confirmed by UV-visible absorption spectra. The protective film formed on the metal surface has been analyzed by FT-IR and AFM spectra. It is found that the protective film consists of Fe²⁺-quercetin-3-O-glucoside complex and Zn(OH)₂.     

Synthesis,Characterization and Inhibition Performance of Vanillin‐Modified Chitosan Quaternary Ammonium Salts for Q235 Steel Corrosion in HCl Solution

In order to enhance the solubility of chitosan in water and its corrosion inhibition performance on Q235 steel in 1 M HCl solution, N‐vanillyl‐O‐2′‐hydroxypropyltrimethylammonium chloride chitosan (VHTC) was synthesized. The structure of VHTC was characterized by FT‐IR and ¹H‐NMR spectroscopy. The corrosion inhibition performance of VHTC on Q235 steel in 1 M HCl solution was studied by weight loss, polarization, electrochemical impedance spectroscopy (EIS) and stereo microscope analysis. Experimental results indicate that VHTC shows better inhibition efficiency compared to chitosan. When the concentration of VHTC increases to 200 mg L^?1, the inhibition efficiency reaches 90 %, which is almost equal to the conventional corrosion inhibitors (e.g., imidazoline). The polarization study demonstrates that VHTC is a mixed‐type inhibitor caused by a geometrical blanketing effect. The charge transfer resistance is proportional to the inhibitor concentration as revealed by the EIS results, indicating that the protective film on the Q235 steel surface is formed by adsorption of the inhibitor molecules. The inhibition efficiency of VHTC achieves the maximum value within 24 h when the concentration of VHTC is 200 mg L^?1. The morphology observation of the corroded steel surface indicates that the corrosion of Q235 steel in 1 M HCl solution is significantly inhibited after introducing VHTC into the acidic solution.     

Amphiphilic amido-amine as an effective corrosion inhibitor for mild steel exposed to CO2 saturated solution: Polarization, EIS and PM-IRRAS studies

The corrosion behavior of mild steel in CO₂-saturated 5% NaCl solution with N-[2-[(2-aminoethyl) amino] ethyl]-9-octadecenamide corrosion inhibitor at 25 °C has been studied by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) measurements. Both potentiodynamic polarization and EIS measurements reveal that this amido-amine precursor inhibits the carbon steel corrosion and the inhibition efficiency increases with increasing the inhibitor concentration. The corrosion inhibitor exhibits high corrosion efficiencies as a mixed-type inhibitor, with a predominant influence on the anode process. The organic inhibitor acts blocking surface sites at low concentrations and by modifying the adsorption mechanism forming a protective barrier against corrosive ions at high concentrations. EIS results show that the mechanism of its corrosion inhibition at concentrations higher than 0.82 × 10⁻⁵ M is by forming a protective bilayer with small pore sizes that hinders the passage of the reactive species. PM-IRRAS measurements demonstrate that the inhibitor is chemisorbed to surface steel. Therefore, its spectrum reveals that the inhibitor monolayer has an amorphous structure.     

In depth analysis of anti corrosion behaviour of eco friendly gum exudate for mild steel in sulphuric acid medium

The current research work was keen to examine the corrosion inhibition efficiency of mild steel (MS) in presence of aqueous extract of Araucaria heterophylla Gum (AHG) in 1?M H₂SO₄ medium. The phytoconstituents of the AHG were interpreted by GC-MS and corrosion inhibition efficiency was deduced using other techniques like weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Adsorption of inhibitor molecules on the mild steel surface was supported by Density Functional Theory (DFT) studies, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). It is seen from the results that the inhibitor exhibits optimum efficiency of 78.57% at 0.05% v/v on mild steel specimen in 1?M H₂SO₄ medium at room temperature. Tafel polarizations clearly show that the aqueous extract of AHG acts as a mixed type inhibitor. The change in the EIS parameters in presence of inhibitor is investigative of the protective layer formation of the mild steel surface. The adsorption is found to obey Langmuir adsorption isotherm. Thermodynamic and activation parameters for the corrosion inhibition process supported the physical adsorption mechanism.     

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.     

Electrochemical synthesis of polyaniline films on zinc-cobalt alloy deposited carbon steel surface in sodium oxalate

Polyaniline (PANI) coatings were electropolymerized on zinc-cobalt alloy deposited carbon steel (CS/ZnCo) electrode from an aqueous sodium oxalate solution using three different scan rates in cyclic voltammetric technique. Scanning electron microscopy (SEM) was used to analyze the surface morphology of the polymer film. The SEM images showed that the increase in scan rate induced an increase in grain size of the PANI film. The corrosion behavior of CS/ZnCo electrodes with and without PANI film in 3.5% NaCl solution were investigated through electrochemical impedance spectroscopy (EIS) and anodic polarization studies. The results of the study showed that the PANI coatings provided significant and effective protection for the CS/ZnCo electrode, in preventing corrosion. In addition, the PANI film that was synthesized at a high scan rate, exhibited the best anti-corrosive performance due to the formation of protective oxide layers through its catalytic efficiency.     

4-氨基苯甲酸席夫碱自组装缓蚀膜对20#钢在饱和CO2油田水中的缓蚀性能

利用邻氧乙酸苯甲醛缩4-氨基苯甲酸钾盐席夫碱(K₂L1)缓蚀剂在20#碳钢表面制备了自组装单分子膜(SAMs),通过电化学方法研究了缓蚀剂的合成条件、自组装时间等因素对成膜的影响,结果表明,合成中KOH与邻氧乙酸苯甲醛按2:1摩尔比进行反应得到的K₂L1缓蚀剂在碳钢表面自组装3 h后,可以形成稳定、致密的缓蚀膜。缓蚀性能的研究表明,碳钢表面K₂L1-SAMS抑制了碳钢的阴极还原过程,改变了电极表面双电层结构,具有良好的缓蚀效果(最高缓蚀效率可达95%以上),交流阻抗和极化曲线得到的结论是一致的。同时研究表明K₂L1的吸附行为符合Langmuir吸附等温式,吸附机理是典型的化学吸附。量子化学计算结果表明,K₂L1分子具有多个吸附活性中心,这些活性原子的前线轨道能与碳钢表面铁原子的前线轨道相互作用,因而使得K₂L1分子在碳钢表面形成吸附膜,阻止了碳钢在饱和CO₂油田水介质中的溶解。X射线光电子能谱(XPS)分析表明,K₂L1通过配位键在碳钢表面形成了稳定的缓蚀膜。     

硫脲基松香咪唑啉季铵盐 对A3碳钢的缓蚀性能研究

合成了硫脲基松香咪唑啉季铵盐,对其结构进行了红外和核磁表征。采用失重法、动电位极化曲线、交流阻抗以及接触角测试分析了目标产物在质量分数为15%HCl溶液中对A3碳钢的缓蚀性能。采用AFM以及XPS测试对产物的吸附膜进行了表征。结果表明：目标产物的缓蚀效率随添加质量分数的增加先增大后减小,当目标产物质量分数增加到占盐酸质量的0.4%时,缓蚀效率最高达到90.78%;此物质是一种阴极控制为主的混合型缓蚀剂;AFM以及XPS结果证实目标产物确实可以在碳钢表面形成缓蚀剂吸附膜。     

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).     

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。     

Corrosion inhibition performance of threonine-modified polyaspartic acid for carbon steel in simulated cooling water

Green polymers as corrosion inhibitors are gradually used to protect metal in solution environment. A polyaspartic acid threonine derivative (PASP-Thr) was synthesized and its structure was characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance. The corrosion inhibition effect of polyaspartic acid (PASP) and PASP-Thr on carbon steel in simulated cooling water was investigated by weight loss tests and electrochemical measurements. Experimental results show PASP-Thr as a mixed-type inhibitor exhibits higher corrosion inhibition efficiency than PASP, and the inhibition efficiency of PASP-Thr reached 93.06% at the dosage was 200 mg L⁻¹. The carbon steel surface in different situations was analyzed using atomic force microscope, scanning electronic microscope/energy dispersive X-ray, and FTIR, demonstrates the formation of a protective film on carbon steel surface. The inhibition effect of PASP-Thr was primarily attributed to the protective film formed on steel surface by physical and chemical adsorption. Moreover, quantum chemical calculation elaborated the relationship between the inhibition efficiency and the PASP-Thr molecular structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47242.     

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.     

一种高效盐酸酸化缓蚀剂的性能评价

采用静态挂片失重法和电化学法考察了缓蚀剂的缓蚀性能,讨论了缓蚀剂加量、温度对腐蚀速率的影响。静态腐蚀评价可知:结果表明,温度为90℃时,在15%工业盐酸介质中N80钢片的腐蚀速率随着缓蚀剂加量的增大而减小、随着温度的升高而增大。当缓蚀剂的加量为1.0%时,仍可获得光亮钢片表面,该缓蚀剂对N80钢片的缓蚀率可达到98%。电化学极化曲线和交流阻抗图谱结果表明:该缓蚀剂对金属腐蚀的阴、阳极过程均有抑制作用,属于混合型缓蚀剂,缓蚀机理属于"负催化效应"。通过电镜扫描照片可知腐蚀容易发生在钢片有局部缺陷的地方,且缓蚀剂的加入可有效的在钢片表面形成保护膜,阻止了腐蚀介质与钢片的接触,抑制金属的腐蚀。     

Effect of H2S on the CO2 corrosion of carbon steel in acidic solutions

The objective of this study is to evaluate the effect of low-level hydrogen sulfide (H₂S) on carbon dioxide (CO₂) corrosion of carbon steel in acidic solutions, and to investigate the mechanism of iron sulfide scale formation in CO₂/H₂S environments. Corrosion tests were conducted using 1018 carbon steel in 1 wt.% NaCl solution (25 °C) at pH of 3 and 4, and under atmospheric pressure. The test solution was saturated with flowing gases that change with increasing time from CO₂ (stage 1) to CO₂/100 ppm H₂S (stage 2) and back to CO₂ (stage 3). Corrosion rate and behavior were investigated using linear polarization resistance (LPR) technique. Electrochemical impedance spectroscopy (EIS) and potentiodynamic tests were performed at the end of each stage. The morphology and compositions of surface corrosion products were analyzed using scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that the addition of 100 ppm H₂S to CO₂ induced rapid reduction in the corrosion rate at both pHs 3 and 4. This H₂S inhibition effect is attributed to the formation of thin FeS film (tarnish) on the steel surface that suppressed the anodic dissolution reaction. The study results suggested that the precipitation of iron sulfide as well as iron carbonate film is possible in the acidic solutions due to the local supersaturation in regions immediately above the steel surface, and these films provide corrosion protection in the acidic solutions.     

Corrosion inhibition of mild steel by aerobic biofilm

Mild steel electrodes were incubated in phosphate-buffered basal salt solution (BSS) having two different aerobic bacteria, viz. Pseudomonas alcaligenes and Pseudomonas cichorii. In the medium containing P. cichorii, significant reduction in the corrosion rate was observed due to the surface reaction leading to the formation of corrosion inhibiting bacterial biofilm. With a view to understand the mechanism of microbially influenced corrosion/corrosion inhibition, electrochemical and biological experiments such as electrochemical impedance spectroscopy (EIS) measurements and biochemical analysis were made. The exposed surfaces were examined using scanning electron micrographs (SEM), energy dispersive spectroscopy (EDS) and electron spectroscopy for chemical analysis (ESCA). The scraped surface film was also examined using FT-IR spectroscopy. The results suggested that mild steel surface contained iron oxide-phosphate layer covered with bacteria and exo polymeric substance (EPS)/iron-EPS complex for P. cichorii and iron oxides and iron phosphate for P. alcaligenes.     

Synergistic Influence of Poly(4-Vinylpyridine) and Potassium Iodide on Inhibition of Corrosion of Mild Steel in 1M HCl

The corrosion and inhibition behavior of mild steel in 1 M HCl in the presence of poly(4-vinylpyridine)(P4VP) and potassium iodide (KI) was investigated using weight loss measurements, potentiodynamic polarization studies and impedance measurements. The inhibition efficiency increased with increasing P4VP concentration. The inhibiting action of P4VP is considerably enhanced by the addition of potassium iodide. The adsorption of this compound either alone or in combination with iodide ions on the metal surface is found to obey Lamgmir's adsorption isotherm. The experimental results suggest that the presence of iodide ions in the solution increases the surface coverage and, therefore, indicate the joint adsorption of P4VP and iodide ions. On the other hand, it was found that the inhibiting effect of P4VP and (P4VP + KI) increased with increasing temperature of the corrosion medium. The presence of these species in the solution decreases the double layer capacitance and increases the charge transfer resistance, both derived from Nyquist plots obtained from a.c. impedance studies. The variation of charge transfer resistance with time suggests that the inhibitive action of (P4VP + KI) depends mainly on the protective inhibitor film formed on the steel surface.     

Effectiveness of some non ionic surfactants as corrosion inhibitors for carbon steel pipelines in oil fields

The ability of new synthesized non ionic surfactants (I and II) to protect carbon steel in acid chloride solution was investigated using potentiostatic polarization, open circuit potential, weight loss and surface tension measurements. The experimental results showed that these inhibitors revealed a very good corrosion inhibition even at low concentrations. The percentage inhibition efficiency (η%) increases by increasing the inhibitor concentration until the critical micelle concentration (cmc) is reached. It was found that, the adsorption ability of the surfactant molecules on carbon steel surface increased with the increase of the molecular size of the surfactant. Potentiostatic polarization curves indicate that the inhibitors under investigation act as mixed type. Finally, the mechanism of carbon steel dissolution in acidic medium was discussed both in absence and presence of the inhibitor molecules.     

CORROSION INHIBITION OF STEEL PIPELINES IN OIL WELL FORMATION WATER BY A NEW FAMILY OF NONIONIC SURFACTANTS

A new family of nonionic surfactants was synthesized and evaluated as corrosion inhibitors for steel pipelines in oil well formation water. Polarization data show that the selected surfactants act as mixed-type inhibitors. EIS results show that the change in impedance parameters (R_t and C_dl) with the concentration of the surfactants studied is indicative of the adsorption of surfactant molecules on carbon steel surface, leading to formation of a good protective film. The properties of this film were studied by various surface analysis tools. Finally, the relation between the surface properties of the inhibitor molecules and corrosion inhibition efficiency is discussed.