Corrosion Mitigation Research Articles

Viable FA based bacterial cells as sustainable solution for corrosion prevention in RC structures

Reinforcement corrosion is one of the biggest challenges faced by the construction industry, with billions of dollars spent on corrosion remediation and prevention. Recently, microbially induced calcium carbonate precipitation (MICCP) has been considered a novel method in corrosion mitigation of reinforced concrete (RC) structures. In the current investigation, fly ash (FA) based inoculum for construction industry was developed and tested for cell viability to define the shelf life of the carrier product. The results indicated that FA-based inoculum possessed a shelf life of 180 days with an effective cell count required to induce MICCP in reinforced concrete. FA-based inoculum was immobilized in fresh concrete supplemented with nutrients to study the corrosion mitigation potential. The prepared specimens were cured for 28 days and then subjected to impressed current-induced chloride corrosion. For corrosion assessment, well established electrochemical technique and a newly emerged electromechanical impedance (EMI) technique were employed separately on different RC specimens. In the electrochemical technique, open circuit potential (OCP), corrosion potential (Ecorr), corrosion current density (Icorr) were obtained over the test exposure; whereas in EMI technique, admittance signatures were acquired for the entire testing duration at an interval of 7 days. Further to examine the changes in admittance signatures, root mean square deviation (RMSD) was used to quantify the corrosion process. Results indicated that Icorr and RMSD were linearly increasing over the test exposure. The results clearly prove that the FA-based carrier material can be effectively used for the corrosion prevention and the emerging EMI technique can efficiently monitor the corrosion process.

Comparison of the Corrosion Inhibition Ability of Different Coumarate-Based Compounds Incorporated into Waterborne Binders

One of the most widely applied methods for the mitigation of corrosion is to cover metallic surfaces with polymeric coatings; however, the barrier properties provided by the polymer may not be enough to prevent corrosion. To improve the performance of the coatings, the incorporation of corrosion inhibitors in their formulation can be done to provide active protection to the system. Among the organic corrosion inhibitors, p-coumaric acid (p-CA) is promising for corrosion protection. Therefore, in this work, the corrosion protection efficiency of four p-coumaric-based inhibitors, methyl (H1), butyl (H4), trifluoromethoxy (HCF3), and p-4-ethyloxymethacrylate p-coumaric acid (HMA), is investigated. The inhibitors are incorporated into environmentally friendly waterborne polymeric binders by batch miniemulsion polymerization. The barrier corrosion protection of the coatings produced from these hybrid latexes is analyzed by electrochemical impedance spectroscopy (EIS) of the intact and scratched coated steel substrates. Of the intact coatings, the one with H1 showed the best response, with impedances of 106.3–106.7 Ω and phase angles of 82–84°, considerably higher than the control without inhibitor (105–105.2 Ω and 60–66°, respectively). The better performance of H1 has been attributed to its higher solubility in the media. However, the best impedance results for the scratched films have been obtained for the coating with HMA, as the impedance was maintained at ∼104.3 Ω for 24 h, while the impedance drops from ∼104.6 to 104.1 Ω for the control scratched sample. As HMA is attached to the polymeric chains, it is likely able to protect the exposed metallic area without completely leaching from the coating, thus explaining why it is able to maintain its performance. The EIS analysis also strongly suggests that the inhibitors have an additional protective effect through increasing pore resistance and decreasing metal corrosion as indicated from the higher Rpore and lower Cdl data extracted from the fits.

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.

Pepper extract effectiveness as a natural inhibitor against corrosion of steel samples (SS) in 1 M hydrochloric acid; Theoretical (DFT calculation – MD simulation), thermodynamic, and electrochemical-surface studies

Recently, researchers have tried to find potential approaches for mitigating the metals' corrosion rate in aggressive environments. In the present study, the exploration of the Pepper extract's impact on the steel samples (SS) dissolution rate reduction in HCl media was done. The extract ingredients were detected by Raman, UV-Vis, and FT-IR approaches. The Pepper extract mechanism and effectiveness in corrosion mitigation were examined by polarization approach and EIS exam. Adsorption of the inhibitive components in the Pepper extract over a steel surface was theoretically studied by DFT calculation and MD simulation. Around 92% efficiency with mixed protection activity was recorded after 6 h of sample exposure to the 800 ppm Pepper extract-included solution at ambient temperature. The FE-SEM and AFM records confirmed the considerable surface degradation reduction on the Pepper extract-containing HCl solution-attacked samples. The weight loss test results have reflected 91% efficiency at 800 ppm and ambient temperature. However, by raising the harsh media temperature up to 55 ºC the anti-corrosion index was reduced 90%. The thermodynamic computation proved the exothermic adsorption of the molecules according to the Langmuir-type isotherm proving the monolayer Pepper extract molecules' interaction with the iron surface. • The Pepper extract's impact on the steel dissolution rate reduction in HCl media was studied. • Adsorption of the inhibitive components in Pepper extract over steel surface was theoretically studied. • Around 92% efficiency with mixed protection activity was recorded after 6 h sample exposure to the 800 ppm Pepper extract.

Evaluation of expired linezolid and norfloxacin drugs as proficient environmentally safe inhibitors for mitigation of aluminum corrosion in sodium chloride medium

This paper highlighted how the expired linezolid and norfloxacin drugs can inhibit the corrosion of aluminum in 1.0 M NaCl. Chemical, electrochemical and microscopic tools were employed. The calculated inhibition efficiencies (% IEs) of the drugs were raised with their concentrations. The corrosion rate of aluminum was increased with rising [NaCl] and the% IEs were increased with the drugs’ concentration and reduced with rising temperature. The acquired higher% IEs were ascribed to strong adsorption of the drugs’ molecules on the aluminum surface and such adsorption was agreed with Langmuir isotherm. Thermodynamic and kinetic parameters were calculated that confirm the mechanism of physical adsorption. The used expired drugs behaved as mixed-kind inhibitors with cathodic priority. The kinetics and mechanisms of corrosion of aluminum and its inhibition by such drugs were explained. The gained results regarding to% IEs illuminated a good concordance between all utilized techniques.

Designing an epoxy composite coating having dual-barrier-active self-healing anti-corrosion functions using a multi-functional GO/PDA/MO nano-hybrid

The graphene oxide, functionalized with polydopamine (PDA) bio-polymers and molybdate (MO) ions, was incorporated into the epoxy coating. The FT-IR, Raman, UV-visible, XRD, and FE-SEM/EDS analyses were utilized for the GO/PDA/MO nanoparticle characterization. The sequence of inhibitors' release from the nano-hybrid and their effect on the electrochemical behavior of the steel sample was explored by the OCP, polarization, and, EIS analyses in the aquatic saline media. EIS analyses revealed inhibition efficiency of 88% for the sample immersed in the GO/PDA/MO-contained solution after 48 h immersion. The polarization results showed a 91% corrosion mitigation index for the sample submerged in the GO/PDA/MO extract-containing solution after 48 h immersion. An increase of the scratched coating Nyquist diameter, the lower corrosion product, and coating blister formation after exposure to the salt spray chamber, as well as the lower adhesion loss in the pull-off test (26%), revealed that the epoxy coating reinforced with GO/PDA/MO nano-hybrids could mitigate the mild steel corrosion by improving the barrier performance and active corrosion protection (self-healing mechanism) behavior.

The Potential of Tinospora cordifolia Extracts as Antibacterial Material against Pseudomonas aeruginosa

Mitigation and control of bacterial corrosion must have been prioritized for failure anticipation by corrosion associated with microorganisms. Using synthetic inhibitor for material protection from corrosion have problems because it is not eco-friendly. This work conducted preliminary studies on T. cordifolia stem extracts at various methanol ratios against P. aeruginosa biofilm as a new eco-friendly inhibitor. The T. cordifolia stem was extracted by the maceration method with a different ratio of methanol solvent (100, 75 and 50 %). The bacterial activity was assessed using the dilution method (MTT assay) to determine the minimum inhibitory concentration (MIC). The total phenolic and flavonoid contents were determined using Follin-Ciocalteu and aluminum chloride (AlCl3) colorimetric, respectively. Meanwhile, the structure of the active compounds in the extract was identified by using the liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). The yields of T. cordifolia extracts are 9.45, 7.56 and 8.40 % at 100, 75 and 50 % of methanol ratios, respectively. The total phenolic content (TPC) in crude methanol extract of T. cordifolia is 11.20, 9.46 and 6.56 % for 100, 75 and 50 % of methanol ratios. Meanwhile, the flavonoid content (TFC) was obtained is about 5.25, 0.64 and 0.33 % for 100, 75 and 50 % of methanol concentrations, respectively. The T. cordifolia extract has antibacterial activity against P. aeruginosa in all ratios of methanol concentrations. The minimum inhibitory concentration (MIC) of T. cordifolia methanol extract was found at 4096 µg/mL. Methanol solvent concentration with the most active antibacterial activity of the extract was 50 %, followed by 75 and 100 %. The structures of the active compound in the methanolic extract of T. cordifolia are a phenolic group, and it is in the alkaloid derivatives (Calopiptin, d-Lirioferine (Lirioferine), Moupinamide, Piperanine, and Yuanhunine). HIGHLIGHTS The crude methanol extract of Tinospora cordifolia stem has potential against aeruginosa in the marine environment The minimum inhibitory concentration (MIC) was found at 4096 µg/mL of extract in a ratio of 50:50 (v/v) of methanol to water The compound structures in cordifolia methanol extracts are Calopiptin, d-Lirioferine (Lirioferine), Moupinamide, Piperanine, and Yuanhunine GRAPHICAL ABSTRACT

Synthesis of gemini cationic surfactants-based pyridine Schiff base for steel corrosion and sulfate reducing bacteria mitigation

Three gemini cationic surfactant with different hydrophobic tails labeled GSBO, GSBD, and GSBH based azomethine and pyridine nuclei have been synthesized and confirmed spectroscopy via FTIR, 1HNMR, and mass spectroscopy. The surface and thermodynamic study were conducted via measurement the surface tension measurements at different temperatures for well examining their corrosion inhibition efficiency. The affinity of the GSBO, GSBD, and GSBH toward micelle formation and adsorption at interface were hydrophobic and temperature dependent. The C-steel corrosion suppression via the synthesized GSBO, GSBD, and GSBH in 1 M H2SO4 were evaluated using electrochemical impedance spectroscopy, weight loss and polarization techniques, demonstrating their efficient affinity to mitigate the steel corrosion. Increasing the surfactant hydrophobicity exhibit higher ability to suppress the corrosion, as confined by the higher inhibition efficiency achieved by GSBH of 94.5 % that matched with higher adsorption affinity as claimed from the surface and thermodynamic investigation. The Tafel examination clarified GSBO, GSBD, and GSBH behaves as mixed type inhibitors following modified Langmuir isotherm. The inhibitors adsorption on C-steel was confirmed by XPS and SEM surface examination. Ultimately the synthesized azomethine based pyridine nuclei showed affinity to mitigate the sulfate reducing bacteria (SRB) with cut-off point observed for GSBO.

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

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

Application of green active bio-molecules from the aquatic extract of Mint leaves for steel corrosion control in hydrochloric acid (1M) solution: Surface, electrochemical, and theoretical explorations

Due to environmental awarenesses and strict restrictions, industries are forced to bring their processes closer to the considered eco-friendly standards. Without a doubt, corrosion is the most obvious problem in industries and inhibitors are among the most applicable materials for metals' corrosion retardation. For this reason, extensive studies have been conducted in the field of green corrosion inhibitors in recent years. The present work concentrated on the evaluation of the bio-molecules from Mint leaves extract on the steel corrosion mitigation in HCl solution. The Mint extract (ME) structures were investigated by FTIR, UV-Vis, and Raman spectroscopies. It was shown by a polarization experiment that Mint extract at 800 ppm caused the current density (icorr) reduction from 1.03 mA/cm2 (for the blank sample) to 0.11 mA/cm2 which was aided by a mixed inhibition (cathodic – anodic) mechanism. The EIS results illustrated that at the optimum condition around 91 % inhibition degree was reached after introducing 800 ppm Mint extract. The weight loss investigations, however, affirmed that a 92 % efficiency was achievable at 25 °C, which was mitigated to 89 % at 55 °C. Eventually, the thermodynamic and adsorption isotherm records represented that Mint extract molecules mono-layer was constructed by utilizing the exothermic interactions. Via the MD and DFT simulations, the interfacial interactions and corrosion inhibitors' adsorption mechanism over the steel surface was exhibited.

Laser-induced carbonization of stainless steel as a corrosion mitigation strategy for high-temperature molten salts applications

New heat transfer fluids are necessary to shift the operation temperature of concentrating solar power plants (CSP) to higher temperatures. Ternary carbonate salts (Li2CO3-K2CO3-Na2CO3) are a promising candidate. However, higher temperature translates to harsher operating conditions for CSP structural components as corrosion is more prevalent. In this work, we explore, for the first time, the use of laser micro-machining technology as a surface modification method to inhibit corrosion of CSP structural materials by molten salts. The corrosion behaviour of SS310 in molten ternary carbonate salt is investigated through static immersion for 600 h. Nanosecond laser treatment results in the adhesion of organic groups in the form of hydrocarbons. These then decompose into carbon and contribute to corrosion inhibition through carbonization and the formation of carbide layers. This is confirmed by the reduced diffusion of Li + ions in the SS310, the formation of denser corrosion products and the protection of chromium oxide layers.

Synergistic anticorrosion effect of Brassica Hirta phytoconstituents and cerium ions on mild steel in saline media: Surface and electrochemical evaluations

Among all the issues that industries will encounter, corrosion is the most concerning. Up to now, corrosion left notable problems in industrial processes and that is why the researchers proposed various methods for limiting its drawbacks. The present work aim is to analyze the impact of Brassica Hirta extract, which is popularly called Mustard, on steel corrosion mitigation and its synergistic effect in mixture with cerium (Ce) cations by using electrochemical and morphological methods. One of the advantages of this inhibitor is its low cost, which is caused by the two factors of the water-based extraction process and the initial cost of the plant purchasing. Moreover, due to the mentioned extraction process, the ME can be considered an eco-friendly inhibitor. In addition, the ME is accessible in most parts of the world. The film composition screening was done by EDS, mapping, and GIXRD techniques, and by FE-SEM and AFM technics, both surface morphology investigation and topographical explorations were done.The findings confirm that the Mustard extract (ME) inhibition impact was boosted in the presence of Ce cations and the mixture performance was optimized at 200:600 ppm ME:Ce mixture concentration. The electrochemical impedance spectroscopy (EIS) and polarization records illustrated that the mixture could retard the corrosion by 94% and 92% of steel corrosion after 48 h of steel immersion, respectively. Also, the synergistic index value of 200:600 ppm ME:Ce ascended steadily from 2.50 until reaching 7.44. The morphology of the film deposited on the surface and its microstructure including ME:Ce complex was demonstrated. The GIXRD analysis outcomes besides EDS and mapping detections confirmed that the protective layer formed includes ME phytochemicals and Ce oxide/hydroxides.

Characterization and evaluation of stable localized corrosion in a 7075-T6 aluminum alloy FSW joint before and after anodizing treatment

The microstructure and corrosion processes of a friction stir welded (FSW) 7075-T6 aluminum alloy joint, before and after anodizing surface treatment, have been characterized by advanced techniques, and the feasibility of anodizing treatment as a corrosion mitigation method has been evaluated. The results showed that different zones of the FSW joint had distinctly different microstructure and consequently different corrosion behavior in NaCl solution. Stable localized corrosion occurred in the transitional regions between the thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ), and was characterized by intergranular corrosion. The intergranular corrosion was ascribed to the galvanic coupling effect between Cu-rich grain boundary precipitates and the precipitates free zones (PFZs). Although anodizing and the subsequent sealing treatments could greatly improve the corrosion resistance of the base metal, the TMAZ/HAZ transition regions still showed much higher corrosion susceptibility than other regions. The high corrosion susceptibility of the FSW joint after anodizing treatment is not ascribed to the difference of the anodic oxide film in the regions, but the heterogeneous microstructure of the alloy beneath the anodic film. The present paper has shown that the stable localized corrosion in the FSW joint is intrinsically stemmed from the welding process itself and traditional mitigation method such as anodizing treatment cannot solve the problem; more effective corrosion mitigation methods are still awaited.

Hybrid Polyurethane/Polypyrrole Composite Coatings on Passivated 316L SS for Surface Protective Action against Corrosion in Saline Medium

Hybrid treatments consisting of surface modification and subsequent protective coatings have gained extensive attention among corrosion mitigation approaches for a wide variety of structural metallic materials. This study aims to review the enhancement of the corrosion protection performance of polyurethane (PU) coatings on 316L stainless steel (SS) specimens. This was achieved via a two-step strategic treatment, primarily by electrochemical passivation and subsequent deposition of PU composite coatings with the different feed ratio of synthesized polypyrrole (PPy) nanoparticles. The effect of different applied voltage on the surface features and the corrosion behavior of the passivated SS surfaces was systematically investigated using surface characterization techniques and a potentiodynamic polarization test in a NaCl solution. Surface morphological images revealed the porous structure on the passivated surface. It is inferred from the topographical surface results that homogeneous surface roughness was achieved with the applied voltage of 5 V. Infra-red spectroscopic results validate the formation of PU/PPy composite coatings and the intermolecular chemical interaction between the PU and PPy moieties. Furthermore, corrosion measurements corroborate the improved corrosion resistance of PU/30PPy coatings with higher values of charge transfer resistance, Rct (1.0869 × 107 Ω cm2), and film resistance, Rf (2.258 × 105 Ω cm2), with the lowest values of corrosion, icorr (4.7 × 10−3 µA cm−2) compared to that of the PU/Bare specimen. In conclusion, it is confirmed that the passivated surface enhances the corrosion resistance performance of PU coated SS, and this performance is further increased with the incorporation of PPy particles.

Protection of Reinforced Concrete Steel Exposed to a Marine Environment: A Preliminary Onsite Study of the Performance of a New Generation of Surface-Applied Corrosion Inhibitors

Reinforcement corrosion is the risk most frequently cited to justify concrete durability research, especially where it is induced by chlorides. Surface-applied corrosion inhibitors are widely used to mitigate the corrosion process both for carbonation and chlorides of steel reinforcement in concrete. They are applied onto the surface of hardened concrete and penetrate towards steel reinforcement. This paper discusses the corrosion inhibition performance of a new generation of a dual-phase surface-applied corrosion inhibitor (DP-SACI), and its efficiency in corrosion induced by chlorides over 3% referred to cement mass, and also in pre- and post-cracked structures. This corrosion mitigation activity was evaluated onsite for almost four years, in a sea wall exposed to XS1 ambiance. The electrochemical techniques used were based on the determination of the electrical resistivity of concrete, the half-cell corrosion potential and the steel corrosion rate (from linear polarization resistance measurements). All of these electrochemical parameters provide accurate information for on-site structures about the efficiency over the time of surface-applied corrosion inhibitors. The effectiveness of the dual-phase surface-applied corrosion inhibitor proved to be up to 99%, even with ongoing corrosion and 0.3 mm cracks near the rebar. The use of DP-SACI provides a non-destructive repair method that inhibits the corrosion process and increases the service life of the element.

Synthesis and Characterization of the Mixed Metal Oxide of ZnO-TiO2 Decorated by Polyaniline as a Protective Film for Acidic Steel Corrosion: Experimental, and Computational Inspections.

In this work, the preparation, characterization, and evaluation of a novel nanocomposite using polyaniline (PANi) functionalized bi-metal oxide ZnO-TiO2 (ZnTiO@PANi) as shielding film for carbon steel (CS)-alloy in acidic chloride solution at 298 K was studied. Different spectroscopic characterization techniques, such as UV-visible spectroscopy, dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) approaches, as well as other physicochemical methods, such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and field emission scanning electron microscope (FESEM), were used to describe the produced nanocomposites. The significance of these films lies in the ZnO-TiO2 nanoparticle's functionalization by polyaniline, a material with high conductivity and electrochemical stability in acidic solutions. The mechanistic findings of the corrosion inhibition method were obtained by the use of electrochemical methods including open-circuit potentials (OCP) vs. time, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The results indicate that the synthesized ZnTiO@PANi is a powerful acidic corrosion inhibitor, and its inhibition effectiveness is 98.86% in the presence of 100 ppm. Additionally, the charge transfer resistance (Rp) value augmented from 51.8 to 432.7, and 963.7 Ω cm2 when the dose of PANi, and ZnTiO@PANi reached 100 ppm, respectively. The improvement in Rp and inhibition capacity values with an increase in nanocomposite dose is produced by the nanocomposite additives covering a larger portion of the surface, resulting in a decrease in alloy corrosion. By identifying the probable regions for molecule adsorption on the steel substrate, theoretical and computational studies provided significant details regarding the corrosion mitigation mechanism. The possibility of substituting old poisonous small substances with inexpensive and non-hazardous polymeric materials as shielding layers for utilization in the oilfield sectors is an important suggestion made by this research.

Investigation of the corrosion inhibition potentials of some 2-(4-(substituted)arylidene)-1H-indene-1,3-dione derivatives: density functional theory and molecular dynamics simulation

BackgroundCorrosion is a threat to material strength and durability. Electron-rich organic inhibitor may offer good corrosion mitigation potentials. In this work, anti-corrosion potentials of nine derivatives of 1H-indene-1,3-dione have been investigated using density functional theory (DFT) approach and molecular dynamics (MD) simulation. Chemical reactivity descriptors like energies of lowest unoccupied molecular orbital (ELUMO), highest occupied molecular orbital (EHOMO), electron affinity (A), ionization potential (I), energy gap (ΔEgap), global hardness (η), global softness (σ), electronegativity (χ), electrophilicity (ω), number of transferred electrons (ΔN) and back-donation (ΔEback-donation) were computed at DFT/B3LYP/6-31G(d) theoretical level. The local reactive sites and the charge partitioning on the compounds were studied using Fukui indices and molecular electrostatic potential (MEP) surface analysis. The adsorption behavior and the binding energy of the inhibitors on Fe (110) surface in hydrochloric acid solution were investigated using MD simulation.ResultsThe high chemical reactivity, kinetic instability and good corrosion inhibition potentials demonstrated by the inhibitors are rationalized based on their high EHOMO, A, σ, ΔN, ΔEback-donation, and low ΔEgap, ELUMO, I and η. A wide difference of approximately 2.4–3.2 eV between the electronegativities of iron and the 1H-inden-1,3-diones suggests good charge transfer tendency from the latter to the low-lying vacant d-orbitals of iron. The heteroatoms (O and N) and the aromatic moieties are the nucleophilic sites on the inhibitors for effective adsorption on the metal surface as shown by condensed Fukui dual functions and MEP analysis. The MD simulation shows good interaction and strong binding energy between the inhibitor and Fe (110) surface.ConclusionsEffective surface coverage and displacement of H3O+, Cl− and water molecules from Fe (110) surface by the inhibitors indicate good corrosion inhibition properties of the inden-1,3-diones. 2-((4,7-dimethylnaphthalen-1-yl)methylene)-1H-indene-1,3(2H)-dione display low energy gap, strongest binding interaction and most stabilized iron-inhibitor configuration, hence, the best anti-corrosion potential.Graphical abstract

Novel textured surfaces for superior corrosion mitigation in molten carbonate salts for concentrating solar power

Corrosion of metals in contact with molten salts used for thermal energy storage and heat transport at high temperatures is a serious impediment to the development of next-generation concentrating solar thermal systems. Toward addressing this limitation, novel multiscale fractal-textured Ni coatings on a variety of substrate alloys are presented in this study for exceptional corrosion mitigation in molten carbonate salts at a high temperature. Strongly adherent, durable, single-layer, and double-layer multiscale fractal coatings were fabricated using the electrodeposition method. Corrosion performance of the coatings on SS310, SS316, SS347, and In800H was studied in molten carbonate salt (32% Li2CO3+33% Na2CO3+35% K2CO3) at 750 °C. Single-layer coatings are stable up to 300 h immersion, whereas double-layer coatings are stable beyond 750 h. The corrosion rate of double-layer Ni coatings on ferrous alloys was reduced by as much as 60% from that of uncoated surfaces and was about 18% below that of higher cost, high Ni content Ha230. The study represents the first-ever report of corrosion characteristics of alloys in carbonate salts at 750 °C and the first demonstration of a means of dramatically reducing corrosion in carbonate salts at a high temperature. The article is significant in that it provides a viable approach for low-cost structural alloys to be corrosion-resistant to molten carbonate heat transfer fluids and storage media in high-temperature concentrating solar thermal applications. The corrosion-resistant coatings provide opportunities for the use of low-cost, ferritic alloys instead of the expensive nickel-based alloys in practice.

Structural evaluation of graphene oxide/Zinc oxide nanocomposite for corrosion mitigation

Owing to the impermeability, high hardness, and hydrophobicity of graphene oxide, there is a growing demand for the development of graphene oxide-based nanocomposite. In this research, GO/ZnO nanocomposite is prepared through a sol–gel route and further spin-coated onto copper to study its potential in corrosion mitigation. This research aims to investigate the structural properties of the nanocomposite formed by various GO sheet sizes and correlate them to the corrosion mitigation mechanism. The different GO sheet sizes were obtained by ultrasonication at 1 h, 3 h and 5 h and the samples were termed as 1 h-GO/ZnO, 3 h-GO/ZnO and 5 h-GO/ZnO, respectively. The X-ray diffraction (XRD) analysis of all samples showed the diffraction peaks at 31.8°, 34.5°, and 36.3° due to the nucleation of ZnO into the graphene structure. The crystallite size of the nanocomposite has decreased with decreasing GO sheet sizes. The Fourier transform infrared (FTIR) spectrometer revealed a strong new peak at 443 cm−1 due to Zn-O characteristic vibrations as compared to as-synthesized GO. The Brunauer-Emmett-Teller (BET) analysis showed that the GO/ZnO nanocomposites exhibited a larger surface area when the GO sheet sizes decreased. The spin-coated sample of 5 h-GO/ZnO showed a higher potential for corrosion protection at 0.017 mm/yr corrosion rate.

Synthesis and structure design of novel unsaturated copolyesters based on indazole moiety in the main chain with good thermal stability for catalytic activity and anti-corrosion applications

Novel unsaturated polyesters based on indazole moiety in the main chain are prepared by interfacial polycondensation of two different indazoline monomers with an acid chloride. The producing copolyesters were confirmed and described by different techniques including Fourier-transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H-NMR). Their crystallinity and thermal stability are measured through X-ray powder (XRD) and thermogravimetric analysis (TGA) and show that they have good thermal stability which is affected by their crystallinity. The morphological features of the synthesized copolyesters were tested by scanning electron microscopy (SEM). Moreover, the resulting copolyesters were intended to be utilized as a catalyst in the preparation of polysubstituted imidazoles produced by three-component ammonium, and acetate 1,2-diketone with an aldehyde under mild conditions. The corrosion mitigation features of the fabricated unsaturated copolyesters as inhibitors for mild steel corrosion in molar hydrochloric acid were investigated. The unsaturated copolyesters exhibited respectable inhibition characteristics owing to robust adsorption on the metal interface and the construction of a defensive layer. The maximum protection capacity values ranged from 94.87 to 98.41% in the presence of 100 ppm of copolyesters. Adsorption of the unsaturated polyesters followed the Langmuir isotherm. Potentiodynamic polarization (PDP) examinations showed that the studied unsaturated polyesters were mixed-kind inhibitors.