Exploration of natural polymers for use as green corrosion inhibitors for AZ31 magnesium alloy in saline environment

Zwitterion modified chitosan as a high-performance corrosion inhibitor for mild steel in hydrochloric acid solution

Herein, a novel chitosan Schiff base (CS-FGA) as a sustainable corrosion inhibitor has been successfully synthesized via a simple amidation reaction by using an imidazolium zwitterion and chitosan (CS). The corrosion inhibition property of CS-FGA for mild steel (MS) in a 1.0 M HCl solution was studied by various electrochemical tests and physical characterization methods. The findings indicate that the maximum inhibition efficiency of CS-FGA as a mixed-type inhibitor for MS in 1.0 M HCl solution with 400 mg L-1 reaches 97.6 %, much much higher than the CS and the recently reported chitosan-based inhibitors. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and water contact angle (WCA) results reveal that the CS-FGA molecules firmly adsorb on the MS surface to form a protective layer. The adsorption of CS-FGA on the MS surface belongs to the Langmuir adsorption isotherm containing both the physisorption and chemisorption. According to the X-ray photoelectron spectroscopy (XPS) and UV-vis spectrum, FeN bonds presented on the MS surface further prove the chemisorption between CS-FGA and Fe to generate the stable protective layer. Additionally, theoretical calculations from quantum chemical calculation (DFT) and molecular simulations (MD) were performed to reveal the inhibition mechanism of CS-FGA.

Control and prevention of microbially influenced corrosion using cephalopod chitosan and its derivatives: A review

Microbially influenced corrosion (MIC) of metals is an important industrial problem, causing 300-500 billion dollars of economic loss worldwide each year. It is very challenging to prevent or control the MIC in the marine environment. Eco-friendly coatings embedded with corrosion inhibitors developed from natural products may be a successful approach for MIC prevention or control. As a natural renewable resource, cephalopod chitosan has a number of unique biological properties, such as antibacterial, antifungal and non-toxicity effects, which attract scientific and industrial interests for potential applications. Chitosan is a positively charged molecule, and the negatively charged bacterial cell wall is the target of its antimicrobial action. Chitosan binds to the bacterial cell wall and disrupts the normal functions of the membrane by, for example, facilitating the leakage of intracellular components and impeding the transport of nutrients into the cells. Interestingly, chitosan is an excellent film-forming polymer. Chitosan may be applied as an antimicrobial coating substance for the prevention or control of MIC. Furthermore, the antimicrobial chitosan coating can serve as a basal matrix, in which other antimicrobial or anticorrosive substances like chitosan nanoparticles, chitosan silver nanoparticles, quorum sensing inhibitors (QSI) or the combination of these compounds, can be embedded to achieve synergistic anticorrosive effects. A combination of field and laboratory experiments will be conducted to test this hypothesis for preventing or controlling MIC in the marine environment. Thus, the proposed review will identify new eco-friendly MIC inhibitors and will assay their potential in future applications in the anti-corrosion industry.

Corrosion inhibition study of 6061 aluminium alloy in the presence of ethyl 5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazole-4-carboxylate (NTE) in hydrochloric acid

The inhibitory effect of an ethyl 5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazole-4-carboxylate (NTE) was investigated on the corrosion of Al (AA6061) alloy at different temperatures (303-333 K) by Electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization (PDP), and weight loss techniques. It was found that NTE molecules protect the aluminium against corrosion and its ability increases with increasing concentrations, and temperature resulting in better inhibitory performance. At all concentrations and temperature ranges, NTE exhibited mixed inhibitor action and complied with the Langmuir isotherm. At 100 ppm and 333 K, NTE demonstrated the highest inhibition efficiency (94%). The EIS results and the PDP results had a good level of concordance. A suitable mechanism for the corrosion prevention of AA6061 alloy was proposed. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to confirm the adsorption of an inhibitor onto the aluminium alloy surface. The electrochemical results were validated by morphological examination, which demonstrated that NTE prevents uniform corrosion of aluminium alloy in acid chloride solutions. The activation energy and thermodynamic parameters were computed, and the results were discussed.

Heteropolysaccharides in sustainable corrosion inhibition: 4E (Energy, Economy, Ecology, and Effectivity) dimensions

Carbohydrate polymers (polysaccharides) and their derivatives are widely utilized in sustainable corrosion inhibition (SCI) because of their various fascinating properties including multiple adsorption sites, high solubility and high efficiency. Contrary to traditional synthetic polymer-based corrosion inhibitors, polysaccharides are related to the 4E dimension, which stands for Energy, Economy, Ecology, and Effectivity. Furthermore, they are relatively more environmentally benign, biodegradable, and non-bioaccumulative. The current review describes the SCI features of various heteropolysaccharides, including gum Arabic (GA), glycosaminoglycans (chondroitin-4-sulfate (CS), hyaluronic acid (HA), heparin, etc.), pectin, alginates, and agar for the first time. They demonstrate impressive anticorrosive activity for different metals and alloys in a variety of corrosive electrolytes. Through their adsorption at the metal/electrolyte interface, heteropolysaccharides function by producing a corrosion-protective film. In general, their adsorption follows the Langmuir isotherm model. In their molecular structures, heteropolysaccharides contain several polar functional groups like -OH, -NH₂, -COCH₃, -CH₂OH, cyclic and bridging O, -CH₂SO₃H, -SO₃OH, -COOH, -NHCOCH₃, -OHOR, etc. that serve as adsorption centers when they bind to metallic surfaces.

Natural Coatings and Surface Modifications on Magnesium Alloys for Biomedical Applications

Magnesium (Mg) alloys have great potential in biomedical applications due to their incomparable properties regarding other metals, such as stainless steels, Co-Cr alloys, and titanium (Ti) alloys. However, when Mg engages with body fluids, its degradation rate increases, inhibiting the complete healing of bone tissue. For this reason, it has been necessary to implement protective coatings to control the rate of degradation. This review focuses on natural biopolymer coatings used on Mg alloys for resorbable biomedical applications, as well as some modification techniques implemented before applying natural polymer coatings to improve their performance. Issues such as improving the corrosion resistance, cell adhesion, proliferation, and biodegradability of natural biopolymers are discussed through their basic comparison with inorganic-type coatings. Emphasis is placed on the expected biological behavior of each natural polymer described, to provide basic information as a reference on this topic.

Inerting Waste Al Alloy Dust with Natural High Polymers: Sustainability of Industrial Waste

A large amount of waste dust will be produced in the process of metal grinding, resulting in a waste of resources and environmental pollution. Therefore, we present a new method of inerting waste aluminum (Al) alloy dust for recycling purposes. Three natural high polymers-starch, pectin, and hydroxypropyl cellulose-were selected to inert waste metal dust in order to prevent the alloy from hydrolyzing and keep the dust pure enough for reuse. The particles of the Al base alloy before and after dust reaction were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infra-red (FTIR), and the relevant reaction mechanism was clarified. The hydrogen evolution test indicated that, across the temperature interval of 313-333 K, 0.75 wt% pectin inerted hydrogen evolution most efficiently (90.125%). XRD analysis indicated that the inerted product is composed of Al monomer and Al₃Mg₂, with no detectable content of Al hydroxide. The purity of the Al alloy dust was preserved. SEM and FTIR analyses indicated that the -OH, -COOH, and -COOCH₃ functional groups in the high polymer participated in the coordination reaction by adsorbing on the surface of the waste Al alloy particles to produce a protective film, which conforms to Langmuir's adsorption model. Verification of the inerted Al alloy dust in industrial production confirmed the possibility of reusing waste Al alloy dust. This study provides a simple and effective method for recycling waste Al alloy dust.

Traditional Chinese medicine extracts as novel corrosion inhibitors for AZ91 magnesium alloy in saline environment

Zingiber officinale Roscoe extract, Raphanus sativus L. extract, Rheum palmatum extract, Coptis chinensis extract, Glycyrrhiza uralensis extract (GUE), Potentilla discolor extract (PDE) and Taraxacum officinale extract (TOE) were screened for the green corrosion inhibitors of AZ91 alloy in saline environment. The experiment results demonstrated that GUE, PDE and TOE can significantly enhance the corrosion resistance of AZ91 alloy by 73.4, 87.6 and 84.6%, respectively. Surface characterization using FTIR, UV–Vis and XPS revealed that the organic compounds of GUE, PDE and TOE can interact with the alloy surface to form a protective physisorbed film, effectively mitigating the corrosion process of AZ91 alloy. The present results may be helpful to discover the new green inhibitors with high inhibition efficiency for AZ91 alloy.

Enhanced Corrosion Resistance of Layered Double Hydroxide Films on Mg Alloy: The Key Role of Cationic Surfactant

In this study, dense anticorrosion magnesium–aluminum layered double hydroxide (MgAl-LDH) films were prepared for the first time by introducing a cationic surfactant tetradecyltrimethyl ammonium bromide (TTAB) in the process of in situ hydrothermal synthesis of Mg-Al LDH films on an AZ31 magnesium alloy. Results of XRD, FTIR, and SEM confirmed that TTAB forms the MgAl-LDH-TTAB, although TTAB cannot enter into LDH layers, and MgAl-LDH-TTAB powders are much smaller and more homogenous than MgAl-CO₃²⁻-LDH powders. Results of SEM, EDS, mapping, and XPS confirmed that TTAB forms the MgAl-LDH-TTAB films and endows LDH films with denser structure, which provides films with better shielding efficiency. Results of potentiodynamic polarization curves (PDP) and electrochemical impedance spectroscopy (EIS) confirmed that MgAl-LDH-TTAB_{x g} films have better corrosion resistance than an MgAl-CO₃²⁻-LDH film. The corrosion current density (i_corr) of the MgAl-LDH-TTAB_{0.35 g} film in 3.5 wt.% NaCl solution was reduced to 1.09 × 10⁻⁸ A.cm⁻² and the |Z|_{f = 0.05 Hz} value was increased to 4.48 × 10⁵ Ω·cm². Moreover, the increasing concentration of TTAB in MgAl-LDH-TTAB_{x g} (x = 0.025, 0.05, 0.1, 0.2 and 0.35) provided denser outer layer LDH films and thereby increased the corrosion resistance of the AZ31 Mg alloy. Additionally, the |Z|_{f = 0.05 Hz} values of the MgAl-LDH-TTAB_{0.35 g} film still remained at 10⁵ Ω·cm² after being immersed in 3.5 wt.% NaCl solution for 168 h, implying the good long-term corrosion resistance of MgAl-LDH-TTAB_{x g} films. Therefore, introducing cationic surfactant in the process of in situ hydrothermal synthesis can be seen as a novel approach to creating efficient anticorrosion LDH films for Mg alloys.

Na2SnO3 functions as outstanding magnesium alloy passivator by synergistic effect with trace carboxymethyl chitosan for Mg–air batteries for standby protection

Coordination of Na2SnO3 with trace carboxymethyl chitosan contributes to standby protection and high utilization efficiency of the AZ61 anode.

Calcite Scale Inhibition Using Environmental-Friendly Amino Acid Inhibitors: DFT Investigation

Scale prevention is a long-term challenge. It is essential for ensuring the optimum utilization of oil and gas wells and minimizing economic losses due to disruptions in the hydrocarbon flow. Among the commonly precipitated scales is calcite, especially in oilfield production facilities. Previous studies on scale inhibitors have focused on investigating the performance of several phosphonates and carboxylates. However, the increased environmental awareness has pushed toward investigating environmental-friendly inhibitors. Research studies demonstrated the potential of using amino acids as standalone inhibitors or as inhibitor-modifying reagents. In this study, 10 amino acids for calcite inhibitors have been investigated using molecular simulations. Eco-toxicity, quantum chemical calculations, binding energy, geometrical, and charge analyses were all evaluated to gain a holistic view of the behavior and interaction of these inhibitors with the calcite {1 0 4} surface. According to the DFT simulation, alanine, aspartic acid, phenylalanine, and tyrosine amino acids have the best inhibitor features. The results revealed that the binding energies were -2.16, -1.75, -2.24, and -2.66 eV for alanine, aspartic acid, phenylalanine, and tyrosine, respectively. Therefore, this study predicted an inhibition efficiency of the order tyrosine > phenylalanine > alanine > aspartic acid. The predicted inhibition efficiency order reveals agreement with the reported experimental results. Finally, the geometrical and charge analyses illustrated that the adsorption onto calcite is physisorption in the acquired adsorption energy range.

Controlling Magnesium Self-Corrosion in Mg-Air Batteries with the Conductive Nanocomposite PANI@3D-FCNT

A promising potential device for storage of large amounts of energy is Mg-air batteries. However, the corrosion of the Mg electrode inside the battery electrolyte limits the battery's capacity to store energy. We present a new strategy to protect the Mg electrode from corrosion and increase the life cycle of Mg batteries in this article. The Mg electrode is coated with a conductive nanocomposite (PANI@3D-FCNT) in this technique. To better understand the anticorrosion properties of PANI@3D-FCNTs and their effect on the battery efficiency, electrochemical and battery tests are used. We discovered that PANI@3D-FCNT plays the most promising role in reducing Mg electrode corrosion in 3.5 wt % NaCl electrolyte, with an efficiency of 93.9%. The battery with the coated Mg electrode has a longer discharge time and a slower drop in operating voltage. The PANI@3D-FCNT nanocomposite will prolong the life of the Mg-air battery and keep the Mg electrode active for a long time. This work outstandingly provides an effective strategy to address the defects in the Mg-air batteries arising from electrode corrosion successfully. The work is a great way to open up new avenues for introducing new conductive nanocomposites in metal-air battery designs without using traditional methods.

Date palm leaves extract as a green and sustainable corrosion inhibitor for low carbon steel in 15 wt.% HCl solution: the role of extraction solvent on inhibition effect

Date palm leaves (DPL) was extracted using acetone (ACE), ethanol (ETH), aqueous (AE), butanol (BUT), methanol (METH), isopropanol (ISO), and ethyl acetate (EHY ACT). The extracts were characterized using Fourier-transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-vis) spectroscopy. The various solvent DPL extracts were screened for anticorrosion property against low carbon steel in 15 wt.% HCl solution at 25 °C. ACE, AE, and ETH DPL extracts are found to promote the corrosion of the low carbon steel while BUT, ISO, METH, and EHY ACT DPL extracts exhibit anticorrosion property. However, BUT DPL extract shows the best anticorrosion property with 400 ppm protecting the low carbon steel by 82%. Based on the results from the screening experiments, BUT extract was selected for a comprehensive corrosion inhibition study. Inhibition effectiveness of BUT DPL extract is found to increase with increasing concentration with 1000 ppm affording 97% protection at 25 °C. The inhibition performance increases up to 40 °C but slightly decreases as the temperature was raised to 50 °C and 60 °C. However, BUT DPL extract could afford 86% protection at 60 °C. Scanning electron microscope and atomic force spectroscopy results confirm that BUT DPL extract is indeed an effective inhibitor for X60 carbon steel in 15 wt.% HCl solution.

Quantum Chemical and Monte Carlo Simulation Studies on Inhibition Performance of Caffeine and Its Derivatives against Corrosion of Copper

Performance tests on caffeine’s corrosion inhibition properties and their derivatives against copper corrosion have been previously reported experimentally using gravimetric and electrochemical analyses. The test was able to measure the efficiency of their corrosion inhibition accurately. However, the caffeine and its derivatives’ structure patterns and coating mechanisms when interacting with metals during copper corrosion inhibition have not been explained in detail by experimental studies. In the present study, the theoretical density functional study (DFT), ab initio MP2, and Monte Carlo simulation approaches explain the problem. The geometrical and quantum chemical parameters of inhibitors were compared under normal and protonated conditions in the gas and aqueous environments. Theoretical studies can accurately determine the molecule’s geometrical parameters and successfully explain the quantum parameters of inhibitors. Molecular dynamics are applied to study the mechanism of interaction between inhibitors and metal surfaces in an explicit water molecule environment. The energy absorption of caffeine and its derivatives on metal surfaces was linear, with quantum parameters calculated from the density functional theory and an ab initio approach. Furthermore, these theoretical study results align with the previously reported experimental studies published by de Souza et al. The inhibition efficiency ranking of studied molecules preventing copper corrosion was caffeine > theobromine > theophylline. This theoretical approach is expected to bridge the gap in designing effective corrosion inhibitors.

Synthesis of a non-hazardous/smart anti-corrosion nano-carrier based on beta-cyclodextrin-zinc acetylacetonate inclusion complex decorated graphene oxide (β-CD-ZnA-MGO)

Recently, the high research considerations have been devoted to designing smart coatings with self-healing propensity along with improved anti-corrosion properties, durability, and effectiveness. In the present work, a novel nano-container, namely beta-cyclodextrin (β-CD), was introduced and applied for encapsulating and subsequent controlled release of a metal-organic inhibitor, namely zinc acetylacetonate (ZnA) in the polymeric matrix. The smart release is another principal object which has been lacked in recent reports. For this aim, graphene oxide nanoparticles were employed to carry the inclusion complexes (β-CD-ZnA) to the defected zones of coatings. FT-IR, Raman, XRD, and UV-vis experiments ascertained that the β-CD-ZnA inclusion complex successfully adsorbed onto the GO sheets modified by 3-aminopropyl tri-ethoxysilane (MGO). The electrochemical inspections (i.e., potentiodynamic polarization and EIS) proved that the β-CD-ZnA-MGO particles could remarkably inhibit the steel corrosion in 3.5 % NaCl solution via mixed cathodic/anodic retardation mechanisms with approximately 93 % efficiency after 48 h metal exposure. It was also found that the corrosion protection performance of the polymeric matrix loaded by β-CD-ZnA-MGO nano-particles enhanced markedly, assigning to the significant epoxy defect coverage by β-CD-ZnA. The intelligent transmission was affirmed by EDS-mapping analysis in the defected regions of epoxy coating. The high quantity of the Zn element ensured the successful adsorption of the ZnA on the metal surface. The damage, as well as the delaminated degrees of the un-scratched epoxy coating, was estimated by the EIS experiment outcomes. Achievements reflected that the presence of β-CD-ZnA-MGO nano-filler in the epoxy resin matrix significantly reduced the electrolyte/ion diffusion. Furthermore, the computational results elucidated from DFT-D approach clarified the stronger β-CD-ZnA affinity towards the GO adsorbent compared with the pure β-CD, supporting the experimental findings.

Thermodynamics, adsorption, and response surface methodology investigation of the corrosion inhibition of aluminum by Terminalia chebula Ritz. extract in H3PO4

This study focuses on investigating the effect of Terminalia chebula Ritz. extract (TCE) for corrosion inhibition of Al in phosphoric acid (H3PO4) using potentiodynamic polarization (PDP) technique. In this study, the effect of concentration of TCE extract, the concentration of H3PO4 acid medium, and temperature (T) was investigated on the corrosion current density (icorr) and inhibition efficiency (IE). The TCE was characterized by FTIR analysis, and the adsorption of TCE was justified with the help of kinetic, thermodynamic, adsorption isotherm parameters. The surface morphology study was done using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), and atomic force microscopy (AFM). The study also focuses on identifying the optimum process parameters for obtaining the maximum IE by applying the response surface methodology (RSM) and desirability function approach. The maximum IE of 83.24% was achieved at a temperature of 30 ℃, the concentration of TCE extract of 500 ppm, and H3PO4 acid concentration of 0.5 M. Regression analysis, Pareto chart, normal chart, main effect, and interaction effect plots are employed to acquire an in-depth understanding of process variables on IE. The IE obtained from the experiments and the predicted model is in a close match and a high value of the coefficient of determination (R2 = 99.98%) displays that the generated model was able to estimate the IE accurately from the selected process variables.