Excellent Corrosion Inhibition Research Articles

Inhibition mechanism of air nanobubbles on brass corrosion in circulating cooling water systems

Air nanobubbles (A-NBs) were used to inhibit the brass corrosion in circulating cooling water for the first time in the study. The results of mass loss method and electrochemical method showed that A-NBs had the obvious corrosion inhibition effect. The inhibition rate reached 52% at 35 °C. The impedance and surface characterization results of corrosion samples indicated that the corrosion inhibition mechanisms of A-NBs mainly included adsorption of corrosion ions, promoting the formation of the passivation film on metal surface and the formation of the bubble layer and scale film on metal surface. A-NBs are potential excellent corrosion inhibitors.

Polymeric smart coatings containing modified capped halloysite nanotubes for corrosion protection of carbon steel

A newly designed smart self-healing epoxy coating system comprised of modified halloysite nanotubes (HNTs) having capping is proposed for corrosion protection of steel. In the first step, HNTs were loaded with 8-hydroxyquinoline (8HQ), used as a corrosion inhibitor. Then the HNTs were sealed/capped using cobalt (II), aiming for an efficient and controlled release of the loaded inhibitor. The smart coatings were developed by reinforcing loaded HNTs into the epoxy matrix. The structural, thermal, mechanical, and electrochemical properties of capped modified HNTs and smart coatings were studied using various techniques. UV–Vis analysis depicted that the capping of the metal-inhibitor complex was decomposed at acidic pH resulting in a controlled release of the loaded inhibitor into HNTs. Electrochemical impedance spectroscopic (EIS) analysis of blank and smart coatings demonstrated that the low-frequency impedance modulus of smart coatings is 109 Ω.cm2 for 20 days compared to blank coatings (105 Ω.cm2), reflecting their excellent corrosion inhibition performance. The superior corrosion protection properties of these smart coatings can be ascribed to the controlled and efficient release of the loaded inhibitor from the capped HNTs. Finally, X-ray photoelectron spectroscopy (XPS) analysis of the steel substrate after the corrosion analysis revealed the adsorption of 8HQ on the steel surface, confirming the formation of iron complex due to the release of loaded inhibitor. This work demonstrated the adeptness of 8HQ in mitigating the corrosion due to the controlled and effective release of the inhibitor from capped HNTs because of dissociation of the metal-inhibitor complex (Co-8HQ).Graphical abstract

Drugs as corrosion inhibitors for the environment

Recently, corrosion-inhibiting compounds have been discovered in a number of medications. In the past, corrosion inhibitors were used by researchers. Corrosion is a significant issue since it is difficult to eradicate completely. When metals interact with their surroundings, their chemical composition and physical properties change. Non-toxic antioxidants, such as organic and inorganic inhibitors, have been prohibited from use in corrosion prevention due to environmental concerns. Drugs can be utilized as corrosion inhibitors due to their minimal toxicity and impact on the environment. Corrosion inhibitors have been evaluated with a wide range of materials, including mild steel, carbon steel, and aluminum (melatonin, cephapirin and tramadol among them). By developing on the surface of mild steel, an insoluble compound has been discovered to inhibit corrosion. Because mass and charge transfer are blocked by the adsorption of modified dapsone medicine on mild steel, corrosion is inhibited. The corrosion inhibition was investigated using EFM, linear polarization resistance, and electrochemical impedance spectroscopy. XRD, SEM, and AFM techniques were utilized to evaluate the Metal surface morphology before to and following drug addition. Researchers discovered that expired Dapsone can be used to make a new corrosion inhibitor. According to an EIS investigation, during the inhibition phase, a charge transfer mechanism is at action. As the inhibitor concentration grew, so did the corrosion rate. Researchers used weight loss and electrochemical technologies to study the effect of cephapirin medications on carbon steel corrosion (CS). Density functional theory simulations revealed that cephapirin is an excellent carbon steel corrosion inhibitor (DFT).

Corrosion inhibition effect of 1-phenyl-5-mercaptotetrazole on nickel-aluminum bronze in seawater: A combined experimental and theoretical study

A combined experimental and theoretical study was performed on corrosion inhibition effect of 1-Phenyl-5-mercaptotetrazole (PMT) on nickel-aluminum bronze (NAB) in seawater. Gravimetric measurement and electrochemical method, such as the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), Tafel polarization curve were used to verify the corrosion inhibition effect of PMT. It was found that the corrosion inhibition efficiency (IE) of PMT achieved 94.4 %, 99.5 %, 98.7 % at a concentration of 1.12 mM, respectively. The slump of the degree of corrosion on NAB surface was also revealed based on SEM and AFM images analysis with the addition of PMT. According to the Langmuir isotherm model based on EIS, PMT was confirmed as a mixed-type corrosion inhibitor between −20 kJ mol–1 and −40 kJ mol–1. Besides, the successful adsorption of PMT on NAB has been revealed by the results of XPS and the change of water contact angle on NAB surface. In combination XPS with quantum chemistry calculations, PMT molecules are adsorbed on the surface of NAB by the active S atom and the tetrazole ring as the major adsorption groups, thus, the protective barrier formed by PMT on the surface of NAB can effectively insulate NAB from contact with seawater. The research results in this paper have showed that PMT as a drug intermediate has an excellent corrosion inhibition effect on the NAB at extremely low concentration in seawater.

A novel phthalocyanine based discotic liquid crystal for efficient corrosion inhibition of mild steel

ABSTRACT Discotic liquid crystals have been extensively investigated for their applications in electro-optical devices. Very recently their potential as corrosion inhibitor has been realised. Effective methods for the prevention of corrosion of mild steel (MS) are still challenging research for industrial chemists. In the present work, MS samples in 1.0 M HCl medium were used to test the corrosion inhibition capacity of a metal-free phthalocyanine (Pc)-based discotic liquid crystal (DLC) using potentiodynamic and electrochemical impedance parameters. The phthalocyanine discotic liquid crystal (PcDLC) exhibited an excellent corrosion inhibition with a maximum inhibition efficiency of 89.61%. This superior ability was attributed to the strong adsorption of PcDLC on to the surface of mild steel as confirmed from the potentiodynamic polarisation data that fit into the cathodic inhibitor category. The protective layer of inhibitors generated on the MS surface was examined using scanning electron microscopy (SEM) and FTIR. The density function theory (DFT) approach was used to investigate the relationship between molecular structures and inhibitory efficacy, which indicated a strong interaction between the inhibitor and the surface iron atoms.

Corrosion Inhibition Mechanism of Ultra-High-Temperature Acidizing Corrosion Inhibitor for 2205 Duplex Stainless Steel

The acidizing corrosion inhibitors reported so far have a poor effect on duplex stainless steel in high-temperature and high-concentration acid systems and cannot effectively inhibit the occurrence of selective corrosion. In this paper, a new acidizing corrosion inhibitor was designed, which was mainly composed of Mannich base and antimony salt. The inorganic substance in the corrosion inhibitor had good stability at high temperatures and could quickly form a complex with the metal matrix to enhance the binding ability. The organic substance can make up for the non-dense part of the inorganic film. The properties of developed corrosion inhibitors were analyzed by quantum chemical calculation, molecular dynamics simulation, and scanning electron microscopy. The results showed that a double-layer membrane structure could be constructed after adding the corrosion inhibitor, which could play a good role in blocking the diffusion of acid solution at high-temperature. The uniform corrosion rate of 2205 duplex stainless steel after adding acidizing corrosion inhibitor immersion in a simulated service condition (9 wt.% HCl + 1.5 wt.% HF + 3 wt.% CH3COOH + 4~6 wt.%) at 140 °C, 160 °C and 180 °C for a 4 h test is 6.9350 g·m-2·h-1, 6.3899 g·m-2·h-1 and 12.1881 g·m-2·h-1, respectively, which shows excellent corrosion inhibition effect and is far lower than that of the commonly accepted 81 g·m-2·h-1 and no selective corrosion could be detected.

Study on Scale and Corrosion Inhibition Performance of Phosphorus-Free Copolymer Hydroxyethyl Methacrylate-Acrylic Acid-Sodium Allyl Sulfonate

A free radical polymerization method was used to synthesize the phosphorus-free copolymer hydroxyethyl methacrylate-acrylic acid-sodium allyl sulfonate (HEMA-AA-SAS). The structure of HEMA-AA-SAS was characterized, and the scale inhibition performance of the copolymer was determined. Near 100% of scale inhibition was achieved when the copolymer concentration was 6 mg/L, suggesting that HEMA-AA-SAS had a significant effect on the inhibition efficiency. The corrosion inhibition performance of the copolymer and the effects under different water quality conditions were determined using a rotating sample method. When the copolymer with 7.5 mg/L was implemented, the corrosion inhibition effect on the carbon steel hanging sheet reached 88.12%. The effects of copolymers on calcium carbonate crystals were analyzed using scanning electron microscopy (SEM) and X-ray powder diffraction (XRD), which showed that the copolymers could destroy crystal morphology effectively. Through the calculation of the corrosion activation energy, the results show that the corrosion activation energy increases and the corrosion reaction rate decreases after the copolymer has been added. The copolymer HEMA-AA-SAS has excellent scale and corrosion inhibition performance.

Potential sustainable electrochemical corrosion inhibition study of Citrus limetta on mild steel surface in aggressive acidic media

Green corrosion inhibitors are of recent interest because of their cost-effectiveness, biodegradability, and eco-friendly characteristics. Plant extracts have been recognized as valuable resources for the corrosion inhibition of metallic alloys. Out of those, one of the most important properties is to exhibit excellent corrosion inhibition on metal surfaces. In the present paper, the corrosion inhibition efficiency of Citrus limetta, commonly known as Mosambi peel extract on mild steel surfaces in an acidic environment has been reported through investigation by some electrochemical methods such as weight loss, potentiodynamic polarization and electrochemical impedance. The investigated green inhibitor was found to exhibit corrosion inhibition efficiency of 93% on the mild steel surfaces in hydrochloric acid media. The adsorption mechanism of the peel extract on a mild steel surface was interpreted and it confirms there is a combination of both physisorption and chemisorption associated with the interaction between the Citrus limetta peel extract and mild steel surface. The extract was characterized using fourier infrared spectroscopy and scanning electron microscopy.

Ambient-stable polyethyleneimine functionalized Ti3C2Tx nanohybrid corrosion inhibitor for copper in alkaline electrolyte

Polyethyleneimine (PEI) was decorated on Ti3C2Tx (M@nP) to solve its oxidation bottleneck in aqueous solutions, and the functionalized Ti3C2Tx could be re-dispersed in 0.5 M NaOH solution as an excellent corrosion inhibitor for copper. Assisted by Coulomb attraction, the ensuing Ti-N bond was responsible for grafted PEI. The anchored polymer chain efficiently capped the oxidation-sensitive defects on Ti3C2Tx, and thus improved its colloidal stability. When the mass ratio of PEI/Ti3C2Tx attained 0.33 (M@0.33P), the aqueous dispersion exhibited the robust shelf-life for 30 days at 25 °C. M@nP acted as a mixed-type inhibitor with dominant anodic effect for copper in NaOH solutions; and M@0.33P can also be the optimal prototype that furthest mitigated copper dissolution. Interfacial cupric/cuprous species reduction by Ti3C2Tx, electrostatic adsorption and electrons sharing of PEI constituted the protective mechanism of M@nP for copper in alkaline electrolyte.

Assessment of the MICP potential and corrosion inhibition of steel bars by biofilm forming bacteria in corrosive environment

The porous network and micro-cracks of concrete facilitate the movement of deleterious ions inside the concrete cover which could corrode the embedded steel. The calcifying bacteria fill up the pore spaces and cracks through a self-healing mechanism, however their capability to precipitate CaCO3 in chlorides rich environment and impact on the corrosion of rebars was unknown. Therefore, the influence of 0%–5% NaCl contents was investigated on the CaCO3 producing capability of four Bacillus strains in this study. In addition, corrosion attributes of steel bars were explored upon interacting with bacteria in the simulated cracked concrete exposed to the 3.5% NaCl solution. The results indicated that on average 1.5% of NaCl content positively affects the bacterial CaCO3 production capability and B. subtilis and B. pumilus produced more CaCO3 at 7 days and 15 days, respectively. Besides, increase in NaCl content significantly altered the type of produced CaCO3 polymorph, microstructure, and crystallinity. The bacterial biofilm forming potential and effect of biofilm on corrosion of steel bars was evaluated through Tafel polarization and electrochemical impedance spectroscopy. The B. subtilis and B. safensis were the optimum strains in developing strong and sticky biofilms during both in-vitro and in-vivo studies and appeared as excellent corrosion inhibitors of reinforcing steel bars compared to the control specimen under an exposure of 3.5% NaCl. Increase in the concentration of NaCl aggregated more bacterial cells together and resulted in the secretion of maximum amount of extracellular polymeric substances. Besides, the biofilm formed by B. safensis was comparatively more uniform and thicker without any blemishes thus considered optimum strain to prevent the corrosion of rebars.

Ethyl ester/acyl hydrazide-based aromatic sulfonamides: facile synthesis, structural characterization, electrochemical measurements and theoretical studies as effective corrosion inhibitors for mild steel in 1.0 M HCl.

In this research paper, aromatic sulfonamide-derived ethyl ester (p-TSAE) and its acyl hydrazide (p-TSAH) were directly synthesized, characterized, and employed for the first time as prospective anticorrosive agents to protect mild steel in 1.0 M HCl conditions. The corrosion efficiency was probed by electrochemical methods including polarization, impedance, and frequency modulation measurements. Optimal efficiencies of 94% and 92% were detected for the hydrazide and ester, respectively, revealing excellent corrosion inhibition. Moreover, both the hydrazide and ester molecules combat the cathodic and anodic reactions correspondingly in a mixed-type manner. The electron transfer (ET) at the inhibitor/metal interface was evaluated using DFT at the B3LYP/6-31g(d,p) level. Natural bond orbital analysis (NBO) and frontier molecular orbital analysis (FMO) calculations showed superior capabilities of the synthesized inhibitors to easily reallocate charge into the metal surface. However, the hydrazide molecules showed slightly better inhibition efficiency than the ester due to the strong interaction between the lone pairs of the nitrogen atoms and the d-orbitals of the metal. The chemical hardness of the hydrazide and ester are 2.507 and 2.511 eV, respectively, in good accordance with the recorded electrochemical inhibition efficiencies for both molecules. Good and straightforward correlations between the experiments and calculations are obtained.

Effect of syzygium cumini leaf extract as a green corrosion inhibitor on API 5l carbon steel in 1M HCL

Corrosion in API 5L steel under 1M HCl is a common issue; hence, creating a more effective and naturally-based inhibitor is critical. In this research, Syzygium Cumini leaf extract (SCLE) was used as a new green corrosion inhibitor under acidic conditions. The inhibition properties of the novel cumini extract were thoroughly characterized using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), Fourier-transform infrared spectroscopy (FTIR), and atomic force microscope (AFM). The results show that the cumini inhibitor has excellent corrosion inhibition with 93 % inhibition efficiency. The adsorption behavior of the inhibitor follows the Langmuir Adsorption Isotherm due to the nearness of R2 to unity. The potentiodynamic and electrochemical measurements demonstrate the mixed type of corrosion inhibitor. Thermodynamic calculation of ΔGads is – 18.41 kJ mol-1 showing the physical adsorption process between the inhibitor and metals. Further inspection of ΔHads at ‒58.93 kJ mol-1 considers releasing energy during adsorption. The FTIR results agree with the increased growth of passive layers due to the adsorption of polyphenol and flavonoids on metals. Remarkably, the adsorption peak at 3266.59 cm-1 corresponds to the adsorption of –OH. The peak at 1612.56 and 1698.4 cm-1 is attributed to C=C and C=O functional groups. The above functional groups serve as adsorption centers to reduce the corrosion effect. The surface treatment of AFM indicated a good relationship with the functional group characterization and confirmed the significant corrosion rate reduction. This work can be used as a benchmark to develop a natural plant as a corrosion inhibitor.

Facile Preparation of a Robust Superhydrophobic SiO2/Epoxy Composite Coating with Favorable Corrosion and Scale Inhibition Performance

Superhydrophobic surfaces with good water repellency are widely studied, but their complex preparation process and poor durability limit their practical application. Herein, a simple and environmentally friendly method to prepare a robust superhydrophobic coating is proposed and its application in the field of corrosion prevention and scale inhibition is explored. Environmentally friendly and low‐cost SiO2 nanoparticles modified by octadecyl trimethoxysilane (ODMS) are mixed with epoxy resin and sprayed onto the surface of metal substrates. The prepared ODMS–SiO2/epoxy resin composite coating has a water contact angle (WCA) of 161.5°, exhibiting excellent superhydrophobicity. In addition, the prepared coating maintains the original microstructure and good superhydrophobicity (WCA is 155°) after 30 cycles of wear test under 200 g load, showing excellent mechanical stability. The inherent superhydrophobic property also endows the coating with excellent corrosion and scale inhibition. The impedance of the composite coating is two orders of magnitude higher than that of the pure epoxy coating. The scaling amount of superhydrophobic composite coating in 24 h is 47% of that of epoxy resin coating. This work provides a new strategy for constructing multifunctional superhydrophobic coatings with excellent mechanical stability, corrosion resistance, and scale inhibition.

Superior Long-Term Corrosion Inhibition of N80 Steel by New Eco-friendly Hydrazone-Based Compounds in a Simulated Oil Well Acidizing Environment: Establishing the Mechanism at the Molecular Level

The acid treatment process of production wells is one of the most acid-induced corrosive processes. Corrosion inhibitors are an effective tool to inhibit the acids employed in acidizing treatments. Herein, new eco-friendly hydrazone-based compounds, namely, 2-(4-isobutylphenyl)-N-((1E,2E)-3-phenylallylidene) propanehydrazide (IPP) and N'-cyclohexylidene-2-[4-(2-methylpropyl)phenyl] propanehydrazide (CIP), were prepared through the functionalization of ibuprofen (IBF) and applied for corrosion mitigation of N80 steel in 15 wt % HCl (referred to hereafter as blank). The anticorrosion performance of selected compounds was investigated by employing weight loss (WL), potentiodynamic polarization curves (PPCs), and electrochemical impedance spectroscopy (EIS), complemented by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. In addition, density functional theory-based tight-binding (DFTB) modeling was conducted to get molecular-level insights into inhibitor-metal bonding. Experimental results revealed excellent long-term corrosion inhibition efficiency at very low concentrations of inhibitors and a mixed-type inhibition process. Numerically, N80 steel polarization resistance increased from 5.51 Ω cm2 in blank to 608.4 and 396 Ω cm2 in blank inhibited with 5 × 10-3 mol/L of IPP and CIP, respectively, equivalent to 99% and 98% inhibition efficiency based on EIS experiments. Besides, SEM and AFM images showed that, after addition to 15 wt % HCl, inhibitors could effectively prevent the acid attack on the N80 steel surface. The fitting of experimental data to adsorption isotherms indicated that inhibitors' adsorption followed the Langmuir isotherm model and mixed physicochemical adsorption on the metal surface. The DFTB simulation revealed that inhibitor molecules can create covalent and physical interactions with iron atoms, which is further confirmed by partial density of states (PDOSs) analysis.

Anti-corrosion performance of novel pyrazole derivative for carbon steel corrosion in 1 M HCl: Computational and experimental studies

• EMPC show excellent corrosion inhibition performance for CS. • Surface morphology of CS samples were examined by UV–Visible, SEM, EDS and XRD. • The Langmuir adsorption isotherm governs the adsorption of EMPC. • DFT and molecular dynamics simulations backed up the experimental findings. The inhibition influence of synthesized ethyl 5-methyl-1-(((6-methyl-4-nitropyridin-3-yl)amino)methyl)-1 H -pyrazole-3-carboxylate (EMPC) on corrosion of carbon steel (CS) in 1 M HCl solution was investigated using mass loss measurements, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements (PDP) techniques. The experimental results show that the inhibition efficiency of EMPC increased with the increase in inhibitor concentration but decreased with an increase in temperature, reaching a maximum of 92 % with 10 −3 M at 303 K. The PDP measurement illustrates the anodic-type behavior of EMPC. The Nyquist plots showed that polarization resistance increased and double-layer capacitance decreased on increasing the concentration of the studied inhibitor due to the adsorption of inhibitor molecules on the CS surface. The adsorption of EMPC on the surface of CS obeyed Langmuir isotherm. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), were employed to examine corrosion products and results indicate a layer being formed on the CS by EMPC that protects the CS from further corrosion. The mechanism of the inhibition process was discussed in light of the chemical structure and quantum chemical calculations of the investigated inhibitor.

Long-term high-temperature resistant biotemplated composite coating for AZ91D magnesium alloy protection

Integrating different active substances through carriers and fully exerting their synergistic corrosion inhibition ability is an efficient anticorrosion strategy. Biotemplate (diatomite) was used to integrate polyaniline and sodium phosphate, an active antiseptic filler (PANI/DM/SP) was prepared in this work. Moreover, active fillers were combined with epoxy resins to prepare high-efficiency anti-corrosion coatings for magnesium alloy protection. The stability of the corrosion inhibitor (sodium phosphate) released by the active filler was analyzed by establishing a mathematical model. Simultaneously, electrochemical impedance spectroscopy tests demonstrate excellent corrosion inhibition properties of active fillers and the impedance modulus of composite coatings was three orders of magnitude higher than that of the EP coating, due to the synergistic effect of each component of the active filler. In addition, the mechanical properties of the composite coating were significantly improved, with tests showing a 51.31% increase in rub resistance and two grades of adhesion improvement (ASTM standard). The key of this work was to give full play to the slow-release characteristics of diatomite through scientific methods and promote the synergistic anticorrosion effect of sodium phosphate and polyaniline.

A Mannich-base imidazoline quaternary ammonium salt for corrosion inhibition of mild steel in HCl solution

The inhibition performance of a novel Mannich base-type imidazoline quaternary salt, namely [N, N-bis(propiophenone), N(-1-polyethyleneployamine-2-stearic-imidazole)] benzyl ammonium chloride (PPLC) for mild steel in 0.5 M HCl was investigated. The experimental results show that PPLC is an excellent corrosion inhibitor, which can retard both the anodic and cathodic reactions through strong chemisorption on the surface. The theoretical results from DFT and MD simulations imply that the active site of PPLC was concentrated on the imidazole ring, carbonyl group and benzene ring, and the PPLC could spontaneously adsorb on the surface of metal in a manner parallel.

Fabrication of multiwalled carbon nanotube‐reinforced rapeseed‐oil‐based polyurethane coatings for anticorrosive applications

AbstractThis work describes the synthesis of a hydroxy‐terminated oligomer for polyurethane preparation (HTO‐PU) from rapeseed oil, salicylic acid and toluene diisocyanate. HTO‐PU was further incorporated with different amounts of multiwalled carbon nanotubes (MWCNTs) to produce HTO‐PU@MWCNT nanocomposites. These nanocomposites were then converted to coatings using mild steel strip as a substrate and allowed to cure at room temperature. Fourier transform infrared and NMR spectroscopic techniques were used for structural elucidation. Surface morphology was determined using scanning electron microscopy and X‐ray photoelectron spectroscopy. Thermal stability (>300 °C) of these coatings was evaluated through thermogravimetric analysis and differential scanning calorimetry. Contact angle values suggest that incorporation of MWCNTs enhanced the hydrophobicity of HTO‐PU coatings. Physicomechanical results reveal that these coatings are highly glossy, scratch resistant and impact resistant possessing good adhesion and excellent pencil hardness. The optimum concentration of MWCNTs was found to be 1.0 wt. %, below and above which the coating performance was observed to deteriorate. The corrosion resistance and barrier properties of these coatings were examined using electrochemical impedance spectroscopy, the results of which suggest excellent corrosion inhibition efficiency of HTO‐PU@MWCNT‐1.0 coatings until 28 days. This study suggests a step towards synthesis of MWCNT‐incorporated green PU coatings for protective applications. © 2022 Society of Industrial Chemistry.

Piroxicam: 2‐hydroxypropyl‐β‐cyclodextrin complex as corrosion inhibitor for the aluminum anode in extremely alkaline‐based primary batteries

AbstractThe corrosion inhibitive capabilities of an aluminum anode in 6 M KOH solution at 50°C with single piroxicam: 2‐hydroxypropyl‐β‐cyclodextrin molecular inclusion complex (PIR: HP‐β‐CD) and mixed PIR: HP‐β‐CD + Na2SnO3 additives are investigated using hydrogen gas collection, weight loss measurement, electrochemical tests, infrared spectra, and scanning electron microscopy (FESEM). The results indicate that the corrosion inhibition efficiency of PIR: HP‐β‐CD additive is increased to 10 ppm concentration (33%). The PIR: HP‐β‐CD adsorbs on the aluminum surface and impedes the accessibility of water to the surface. On the other hand, using only 0.002 M Na2SnO3 reduced aluminum's anodic dissolution and did not provide sufficient efficiency in inhibiting hydrogen evolution. However, adding 10 PIR: HP‐β‐CD to KOH solution containing 0.002 M Na2SnO3 has created a synergistic effect in corrosion inhibition. The highest electrochemical activity, the lowest hydrogen evolution rate (4.48 ml cm−2 s−1), the highest inhibition efficiency (81.14%), and the highest capacity are attained in the 6 M KOH solution with the mixed additives. Indeed, the 10 ppm PIR: HP‐β‐CD + 0.002 M Na2SnO3 additives could be recommended as an excellent corrosion inhibitor in extremely alkaline electrolytes for the aluminum anode at high current densities.

A new 1,2,4-triazole derivative as an excellent corrosion inhibitor: Electrochemical experiments with theoretical validation

In the present investigation a triazole derivative, 4-{(E)-[(4-hydroxy-3-methoxyphenyl)methylidene]amino}-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (HMPT) has been synthesized. The inhibition efficacy of HMPT has been studied on carbon steel in 1 M hydrochloric acid solution by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization techniques (PDP), electrochemical frequency modulation (EFM), and linear polarization resistance (LPR) techniques. The results revealed that HMPT has significant inhibitory effects for the corrosion of carbon steel in an acid medium and displayed around 95% inhibition efficiency at optimum HMPT concentration with decrease in the current density value from 279.9 μA/cm2 to 153.8 μA/cm2. PDP studies signified mixed-type inhibition of HMPT. The mechanism of inhibition is believed to be occur by the adsorption of HMPT on the carbon steel surface and obeyed Langmuir adsorption isotherm. The values of Gibbs free energy of adsorption indicated that the adsorption of HMPT molecules on carbon steel takes place by both physical and chemical adsorption processes. The SEM/EDX studies confirmed the adsorption of HMPT on the carbon steel surface. The quantum chemical studies have provided good support to the experimental results. The promising results indicate the proposed inhibitor HMPT as a possible corrosion inhibitor for protecting the metallic components effectively from corrosion.