Corrosion Inhibition Effect Research Articles

Properties of Salicylidene-Aniline as a Corrosion Inhibitor in Oil and Petroleum Products Transportation Systems

Introduction. Risks of accidents and fires during transportation and pumping of oil and petroleum products is a significant problem of technosphere safety. The reasons may be leaks due to corrosion damage to pipelines, tanks and oil storage tanks. In view of the possible serious financial, environmental and social consequences of such incidents, it is important to constantly seek new, more effective approaches to preventing corrosion processes. It is obvious, for example, that at present not all chemical compounds capable of suppressing or inhibiting the destruction of metals and alloys have been thoroughly studied. The presented scientific work is partly aimed at overcoming the lack of data in this area. The objective is to investigate an insufficiently studied compound salicylidene-aniline, which can be a corrosion inhibitor similar to other nitrogen-containing compounds similar in structure and composition.Materials and Methods. The gravimetric method was used to study the inhibitory, adsorption and complexing properties of salicylidene-aniline. The experiments were carried out with St3 steel plates. The mass of metal samples without an inhibitor and with an inhibitor was recorded before and after exposure in the test media. The effect was determined by the change in the corrosion rate. When setting up experiments, the authors were guided by GOST 9.905–82 "Unified system of corrosion and ageing protection. Corrosion test methods. General requirements". The volume of the corrosive medium was determined according to GOST 9.506–87 "Unified system of corrosion and ageing protection. Corrosion inhibitors of metals in water-petroleum media. Methods of protective ability evaluation". The corrosion criteria were taken from GOST 9.908–85 "Unified system of corrosion and ageing protection. Metals and alloys. Methods for determination of corrosion and corrosion resistance indices". The calculations were based on the valuation principle, which sets the ratio of a multiplicative metrized linear order on a set of particular criteria. An integral indicator based on mathematical and methodological approaches was used for ranking.Results. The effect of hydrochloric acid medium on steel samples St3 was studied. Four concentrations of the inhibitor were taken: 0 %, 0.01 %, 0.1 %, and 0.2 %. The mass of metal samples without an inhibitor and with an inhibitor was recorded before and after exposure in the test media. The effect was determined by the change in the corrosion rate. The mass index of corrosion was calculated. The surface quality during destruction and corrosion inhibition was determined in five stages: the elements to be evaluated were selected, the purpose of the evaluation was formulated, the elements of the technical condition of the object under study were found, the essence of determining the usefulness or value of the criterion was described, and the essence of optimization was explained. The studied properties were ranked with respect to the multiplicative metrized linear order on a set of particular criteria. For the calculations, the task was set — to determine the components of vector B in accordance with one of the evaluation stages. We are talking about the stage when the usefulness or value of the criterion is analyzed by points on the numerical axis indicating the state of the object "better — worse". We constructed an indicator z approximating a known or specified (learning) matrix of paired relationships between objects. The resulting indicator allowed us to assess the technical condition of the surface during the course of corrosion and when it slowed down due to the addition of salicylidene-aniline. The result was obtained for samples with a surface area from 10.1∙10-4 m2 to 11.9∙10-4 m2. During the experiment, the mass of the metal decreased by 0.2–0.8 times with the inhibitor and almost by 3.5 times without it. The mass index of corrosion was recorded from 0.15 g/m2∙h to 0.48 g/m2∙h. At the same time, the protective ability of the inhibitor was quite high: the minimum was 77.4 %, the maximum was 94.8 %. This is a convincing indicator. It is also worth mentioning such an advantage of salicylidene-aniline as a low danger. Its hazard class is III (for comparison: the hazard class of aniline is a level higher — II).Discussion and Conclusion. The authors propose to use salicylidene-aniline as a means to increase the safe service life of oil pipelines and tanks. The potential of this composition as an effective corrosion inhibitor, highly soluble in oil and petroleum products, has been proven. Such properties of salicylidene-aniline as slow oxidation and moderate toxicity are noted.

Effect of Tannic Acid on the Corrosion Behavior of W18Cr4V in a Simulated Wood Environment and Its Inhibition Mechanism

This study explores the effect of tannic acid on the corrosion of woodworking tool material W18Cr4V in a simulated wood environment. The weight loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy were used to study the corrosion and the corrosion inhibition process of W18Cr4V in an environment of acetic acid solution with different concentrations of tannic acid. The results show that after continuous immersion for 20 h, low concentrations (1 wt% and 3 wt%) of tannic acid promoted the corrosion of W18Cr4V, while high concentrations (5 wt% and above) of tannic acid had a significant anti-corrosion effect, with a corrosion inhibition efficiency of about 64% for 10 wt% tannic acid. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy were used to further verify and elucidate the inhibition mechanism. It was found that tannic acid can form a dense and effective corrosion inhibition film composed of iron–tannin complexes on the surface of W18Cr4V. This study not only provides a new perspective on understanding the corrosion effect of tannic acid on woodworking tools but also offers new insights for developing effective bio-corrosion protection strategies.

Tailoring epoxy coating with acetoxime derivative of zinc for advanced anticorrosive performance on mild steel: experimental and computational insights.

In this work, the corrosion inhibitive effect of acetoxime derivative of zinc chloride, (ZnCl2.2HON=C(CH3)2) (ZA), was investigated on mild steel in epoxy/polyamide coating. ZA was used to modify diglycidyl ether of bisphenol A (DGEBA) to yield novel anticorrosive coating (epoxy-ZA) with excellent barrier characteristic. The dispersal of ZA may lead to the formation of Zn-O-C and O-Zn-O linkages in the polymer framework which act as inorganic fillers producing a dense structure of hybrid coating. In electrochemical findings, electrochemical impedance spectroscopy (EIS) and Tafel polarization (TP) indicate higher protection efficiency for epoxy-ZA coatings (99.99 and 99.93 % for EIS and TP, respectively) as compared to others. Using surface analysis and electrochemical data, it was concluded that an inhibition synergy was developed when ZA was taken instead of acetoxime or zinc chloride (ZC) alone in the coating formulation. Fourier transform infrared (FT-IR) was used to investigate epoxy interaction with zinc compounds and scanning electron microscopy (SEM) was used to investigate morphology of the samples. To reinforce the experimental results, reactivity of crosslinked epoxy and epoxy-ZA coatings with metallic surface was also explored using density functional theory (DFT) with basis set B3LYP/6-311G(d,p) and molecular dynamics (MD) methods by using Forcite module. Modification of epoxy with ZA enhances its interaction with steel surface in dry as well as in wet conditions as indicated by the adhesion energy calculated by MD simulations.

Natural chitosan-based carbon dots as an eco-friendly and effective corrosion inhibitor for mild steel in HCl solution

Polysaccharide chitosan and L-histidine were applied to synthesize chitosan-based carbon dots (CA-CDs) by a simple laser ablation method. After characterization of the CA-CDs by FT-IR, UV–vis, Raman, XRD, TEM, and XPS, the CA-CDs were introduced as an eco-friendly and high-performance corrosion inhibitor for mild steel (MS) in 1.0 M HCl solution. The inhibition action and mechanism of CA-CDs were determined by weight loss and electrochemical measurements, in combination with SEM, AFM, and XPS. The results show that CA-CDs as mixed-type inhibitors could effectively weaken the corrosion of MS in 1.0 M HCl solution, and their maximum inhibition efficiency reaches 97.4 % at 40 mg L−1. The adsorption behavior of CA-CDs well obeys the Langmuir adsorption isotherm containing both chemisorption and physisorption. The chemisorption mainly results from the multiple adsorption sites in the CA-CDs, and the physical adsorption is due to the blocking and barrier effect of CA-CD nanoparticles. Both adsorption behaviors were proposed to elucidate the corrosion inhibition mechanism of CA-CDs.

Synthesis, description, and application of novel corrosion inhibitors for CS AISI1095 in 1.0 M HCl based on benzoquinoline derivatives

This study aims to synthesize and evaluate the corrosion inhibition properties of three newly prepared organic compounds based on benzo[h]quinoline hydrazone derivatives. The compounds structure were characterised using FTIR, 1H-NMR, 13C-NMR and Mass spectroscopy. Electrochemical methods, including Potentiodynamic Polarization (PP), Electrochemical Frequency Modulation (EFM), and Electrochemical Impedance Spectroscopy (EIS) were employed to evaluate the compounds as corrosion inhibitors in HCl (1.0 M) for carbon steel (CS). Additionally, surface examination techniques such as scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to investigate the surface morphology and elemental composition of the CS before and after exposure to the synthesized compounds. The electrochemical measurements showed that compound VII achieved corrosion inhibition efficiency. SEM and EDX analysis further confirmed the creation of a passive film on the CS surface. These findings demonstrated the potential of benzo[h]quinoline hydrazone derivatives as effective organic corrosion inhibitors for CS in aggressive solution.

Correlation between experimental and theoretical approaches in the performance of new epoxy resin as an effective corrosion inhibitor for mild steel in acid pickling bath

In this recent work, novelty epoxy resin namely 1,3,4,5,6-pentaglycidyloxy hexan-2-one (PGH) was synthesized characterized and studied as a potential anticorrosive protection for mild steel (MS) in 1 M HCl solution. The corrosion inhibition for MS was examined by “potentiodynamic” polarization (PDP), electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation measurements (EFM), scanning electron microscope coupled with energy dispersive X-ray spectroscopy (MES/EDS) and theoretical approaches (DFT and MD simulation). PGH elaborated was investigated by the Fourier transform infrared (FTIR) spectroscopy. Additionally, the inhibitory efficiencies found at higher concentration (10−3 M of the PGH) are 85.5% (EIS) and 88.6% (PDP), respectively. PDP results indicated that the PGH acted as a mixed-type inhibitor in 1 M HCl medium. SEM/EDS characterization represents a terrific decrease in corrosion of the MS surface within 10−3 M of PGH compared with the 1.0 M HCl pure. DFT calculation provided molecular level insights on the nature and the active centres of the corrosion inhibition efficiency of the PGH elaborated. MD simulation showed that the PGH has the maximum inhibition efficiencies at oxygen atoms.

Constructing bi-functional Ce-MOF on carbon fiber endowing epoxy coating with excellent anti-corrosion and erosion wear resistance

The limited interfacial combination between CF and polymer matrix caused by the chemical inertness of CF surface greatly restricts the protective capability of carbon fiber reinforced polymer coatings (CFRPCs), which could not effectively resist the impact of external forces, especially in the severe and complicated ocean environment (like deep-sea area and splash zone). Hence, it is the crux to enhance the interface compatibility and interface strength between fiber and resin. Based on the reliable compatibility between imidazole and epoxy as well as the corrosion inhibition effects of cerium-based compounds, a kind of bi-functional metal-organic framework (MOF) called the cerium-imidazole framework (Ce-MI) was constructed on the CFs surface via in-situ growth method to improve the interface compatibility and interface strength of fiber and resin and further increase protective performance of epoxy (EP) coating under the simulated deep-sea area and splash zone. After 168 h immersion under alternating hydrostatic pressure, CF@Ce-MI/EP coating displayed impressive impermeability and anti-corrosion performance, and the interfaces of fiber/epoxy adhered firmly. After the erosion wear test, the volume loss and mass loss of CF@Ce-MI/EP were decreased by 23.77% and 14.80%, respectively, compared with CF/EP. Finally, we discussed the protective mechanism of composite coating to reveal the different processes of interface failure caused by the high pressure and the impact of solid particles, respectively.

Corrosion inhibition effect of mebendazole on 5Cr pipeline steel in 1 M HCl solution

In this manuscript, the ability of (5-Benzoyl-1H-benzimidazol-2-yl) carbamicacidmethylester (mebendazole, MBD) as an inhibitor of corrosion on 5Cr pipeline steel in HCl medium was explored. Corresponding electrochemical tests, immersion tests and other experiments were designed, and at the same time, the ability of mebendazole to inhibit corrosion of 5Cr steel in HCl medium was screened and proved by means of molecular weight simulation calculation analysis process, and its possible anticorrosion mechanism was also revealed. Electrochemical test results show that mebendazole can successfully prevent 5Cr steel from dissolving in HCl medium, and the inhibition efficiency is particularly significant with the increase of mebendazole content. According to the electrochemical impedance test, the highest corrosion inhibition efficiency (η) can reach 94.4 %. The results of immersion weight loss experiment are highly consistent with the electrochemical test data and SEM electron microscope morphology. From the theoretical calculation results, it can be found that under neutral conditions and protonated mebendazole molecules have lower energy gaps and higher dipole moments in solvated and unsolvated environments, and can Parallel adsorption on the metal surface, which also corresponds to its efficient corrosion inhibition performance. In addition, through comparison, it is found that the protonated mebendazole molecule under solvation conditions has the highest binding energy, that is, it is the easiest to interact with 5Cr steel and presents the best anti-corrosion performance.

Experimental and computational studies of the corrosion inhibitive effects of Zingiber officinale rhizomes on mild steel corrosion in acidic solutions

The study investigates the anticorrosion potentials of Zingiber officinale (ZO) on mild steel induced in 1.0 M HCl and 0.5 M H2SO4 acid solution respectively using structural characterization (gas chromatography-mass spectroscopy, GC-MS and Fourier transform infrared spectroscopy, FTIR) and electrochemical (electrochemical impedance spectroscopy, EIS and potentiodynamic polarization, PDP) techniques respectively and theoretical simulations. The structural characterization was performed to identify chemical constituents and functional groups present in the plant extract whereas electrochemical techniques and theoretical computations were used to examine the anticorrosion potentials of the extract and validate the experimental results. The GC-MS result revealed the presence of twenty-three (23) compounds within the extract and out of which three (1-(1,5-dimethyl-4-hexenyl)-4-methyl-, dodecanoic acid and 9-Octadecenoic acid (Z)-2-hydroxy-1-(hydroxymethyl)ethyl ester) were selected for computational simulation and the results of FTIR revealed the presence of the following functional groups (O-H, C=C, C=O, C-C and C-H) in the ZO extract. The results of EIS revealed that extract of ZO exhibited corrosion inhibition efficieny of 82.7% and 93.6 % for mild steel in 1 M HCl and 0.5 M H2SO4 solution respectively at maximum inhibitor concentration of 1000 mg/L for mild steel. Also, PDP results revealed that ZO extract functioned as mixed inhibitor because both the anodic and cathodic reaction process was altered. The quantum chemical calculation results revealed that 9- Octadecenoic acid (Z)-2-hydroxy-1-(hydroxymethyl) ethyl ester had a good energy gap (\Delta E) compared to other two compounds, indicating its better adsorption interaction with the metal surface in sulfuric acid environment. This was further confirmed by its good adsorption energy of -355.55 Kcal/mol with mild steel surface in H2SO4 environment compared with -167.81Kcal/mol in HCl environment from the molecular dynamic simulation.

Fish processing discards extract as an eco-friendly corrosion inhibitor for carbon steel in hydrochloric acid

The objective of this study is to extract amino acids from fish processing discards for the preparation of highly effective and degradable corrosion inhibitors. The composition of fish processing discards extract (FPDE) was characterized by HPLC and FTIR. The results showed that the main components of FPDE are amino acids and contain a large number of unsaturated functional groups. Electrochemical techniques (electrochemical impedance spectroscopy (EIS) and Tafel), surface analysis (XPS and AFM), and molecular dynamics simulations (MDS) were conducted to investigate the corrosion inhibition mechanism of FPDE for carbon steel in 1 mol/L HCl. As shown by electrochemical tests, FPDE exhibits mixed-type corrosion inhibition with a maximum inhibition efficiency of 93.3%. FPDE exhibits excellent corrosion inhibition properties on carbon steel surfaces by forming a high coverage film through chemisorption and physisorption. Indeed, the advantages of remarkable inhibition efficiency and facile extraction methods allow FPDE to become a promising corrosion inhibitor for practical applications.

Experimental Investigation of the Weakening Effect of Corrosion Inhibitors on the Performance of Kinetic Hydrate Inhibitors

Experimental Investigation of the Weakening Effect of Corrosion Inhibitors on the Performance of Kinetic Hydrate Inhibitors

Three novel dendritic chitosan derivatives for inhibiting acid corrosion of petroleum pipelines

In the process of exploration and development of oil and gas fields, the acidic environment of oil reservoir, production and transport processes cause corrosion of pipelines and equipment, resulting in huge economic losses and production safety risks. Corrosion inhibitors were widely used in oil industry because of simple operation process and economical. In this study, three environmentally friendly corrosion inhibitors were synthesized based on the natural polysaccharide chitosan. Corrosion inhibition of three dendritic chitosan derivatives (We name them BH, CH and DH) on mild steel in 1 mol/L HCl solution with natural ventilation system was evaluated by weight loss experiment, electrochemical analysis and surface morphology characterization. The experimental results showed that when the three dendritic chitosan derivatives added in the corrosive medium were 500 mg L−1, the corrosion inhibition efficiencies were all more than 80%. Based on quantum chemical calculation, inhibition mechanisms of three dendritic chitosan derivatives were investigated according to molecular structures. The results showed that the benzene ring, Schiff base and N atom contained in the molecule were the active centers of electron exchange, which were more likely to form a film on the carbon steel surface, thereby slowing or inhibiting corrosion. The results also predicted the corrosion inhibition effect BH > DH > CH, which was consistent with the experimental conclusion.

Predicting corrosion inhibition efficiencies of small organic molecules using data-driven techniques

Selecting effective corrosion inhibitors from the vast chemical space is not a trivial task, as it is essentially infinite. Fortunately, machine learning techniques have shown great potential in generating shortlists of inhibitor candidates prior to large-scale experimental testing. In this work, we used the corrosion responses of 58 small organic molecules on the magnesium alloy AZ91 and utilized molecular descriptors derived from their geometry and density functional theory calculations to encode their molecular information. Statistical methods were applied to select the most relevant features to the target property for support vector regression and kernel ridge regression models, respectively, to predict the behavior of untested compounds. The performance of the two supervised learning approaches were compared and the robustness of the data-driven models were assessed by experimental blind testing.

Corrosion inhibition effect of expired ibuprofen drug on copper in sulfuric acid solution

The application of copper as a material in various fields is widely recognized. However, in acidic environments, the electrical and mechanical properties of copper undergo negative alterations, resulting in its dissolution. To protect copper from degradation, the most effective approach is to employ inhibitors. Hence, in this paper, the expired ibuprofen drug has been investigated as a corrosion inhibitor for copper in 0.5 M H2SO4, employing weight loss and electrochemical tests. Compared with the pharmaceutical products used by other researchers in this field, the results showed that ibuprofen is highly effective in protecting copper from corrosion. It was noted that the inhibitory efficacy of ibuprofen increases with concentration. In addition, it was found that its adsorption follows Langmuir isotherm.

Outstanding thermally conductive and anticorrosive polymer composite coating via a multifunctional epoxy curing agent zinc dimethacrylate

Highly thermally conductive metallic materials show great promise in thermal management field. Whereas, inherently high susceptibility of metal materials to corrosion medium would shorten service life and affect heat transfer properties of corresponding materials, thus invalidating their applicability to thermal management devices. This study solves this by preparing an epoxy composite coating with integrated high thermal conductivity (TC) and well long-term corrosion protection performance via synthesizing zinc dimethacrylate (ZDMA) as a novel multifunctional epoxy resin curing agent and designing “point-surface” heterostructure of recrystallized ZDMA nanoparticles-modified boron nitride (BN) sheet with both thermally conductive and anticorrosive functions. The findings reveal that the “double bridging effect” provided by ZDMA and well-dispersed filler result in the formation of efficient heat conduction pathways and barrier effect in the coating. The final coating (h-ZBN/Z/EP) exhibits a high TC of 2.55 W/(m·K), which is more than 11 times that of pure epoxy coating and is much higher than the TC reported for other anti-corrosion polymer coatings. Case calculation and finite element simulation show that the coating can maintain well heat transfer performance of the coated metal material compared to pure epoxy coating. Further combined with the corrosion inhibitory effect of Zn2+ ions, the low-frequency impedance of h-ZBN/Z/EP coating is still as high as 1.32 × 1011 ohm·cm2 after immersion in 3.5 wt% NaCl solution for 360 days. This ingenious strategy provides a fascinating and simple method for preparing multifunctional composite coatings used for long-term protection of heat conduction metallic materials.

Electrochemical explorations, SEM/EDX analysis, and quantum mechanics/molecular simulations studies of sustainable corrosion inhibitors on the Cu-Zn alloy in 3% NaCl solution

Essential oils (EOs) have recently gained attention as sustainable corrosion inhibitors due to their biodegradability, environmental friendliness, low cost, and easy availability. This paper aimed to investigate the synergistic impact of the active green molecules from two essential oils (EO16/EO18) derived from A. visnaga (L.) Lam on the corrosion of Cu-Zn alloy (brass) in a 3% NaCl environment using open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS), surface morphology analysis and computer modelling methods, including density functional theory (DFT) and Monte Carlo (MC) simulations. The electrochemical results demonstrated show that EO18 and EO16 at an ideal concentration of 2 (g/L) and after 6 h of immersion at 298 K, exhibited high inhibition efficiencies (ƞPDP(%), reaching a maximum of 93.04% and 84.57%, respectively. Moreover, the PDP experiments revealed that EO16 and EO18 acted as mixed inhibitors, with a predominant cathodic inhibitory behavior. Additionally, EO16 and EO18 have strong inhibitory efficacy throughout a wide temperature range (298–338 K), especially EO18. Also, the thermodynamic parameters showed a good relationship with the inhibition efficiency of the EO16/EO18. The examination of surface morphology (SEM/EDX) indicated less degradation of the metallic surface in the presence of both EOs in a corrosive environment, with the formation of resistant protective films, particularly notable for EO18. These findings confirmed the adsorption of EOs molecules onto the active sites of the brass surface, facilitated by the synergistic action of various phytochemical elements, including oxygenated monoterpenes/sesquiterpenes (minor compounds) and major compounds (Croweacin/Linalool). Furthermore, computational investigations utilizing DFT and MC simulations revealed a significant adsorption of EO18/EO16 compounds (both major and minor components) onto Cu (111) and Zn (110) surfaces. The MC simulation results further demonstrate that the synergistic effect of EO18 compounds on Cu/Zn surfaces results in the formation of stronger and more protective layers compared to the synergistic effect of EO16 compounds. These computational findings align well with the results obtained from experimental inhibition efficiencies. The combination of experimental and computational approaches enhanced our understanding of the corrosion inhibition mechanism and underscored the potential of EOs as sustainable and effective corrosion inhibitors. These findings can serve as a useful guideline for future research aimed at investigating the synergistic inhibitory impact of the components present in the green extracts.

Development of a promising nontoxic corrosion inhibitor based on Opuntia dillenii seed oil for iron corrosion in 3Wt% NaCl: Experimental and theoretical approaches

This work concentrates on the application of an eco-friendly and non-toxic formulation based on Opuntia dillenii seed oil (labeled FOD) as a new corrosion inhibitor for iron in 3% NaCl solution. We assessed the potential toxicity of FOD through the oral acute toxicity test. Then, the anticorrosion behavior was conducted at different concentrations, temperatures and immersion times using gravimetric and electrochemical methods. The study exhibited a highest inhibition efficiency of 93% obtained at 750 ppm. The formation of a complex between FOD and metallic surface was confirmed by UV-visible spectroscopy. Surface analysis confirmed the ability of the inhibitor to form a film to protect the metal against electrolyte attack. The theoretical aspect elaborated using molecular dynamics (MD) simulation and density functional theory (DFT) supported all experimental results by illustrating similar trend of inhibition efficiencies and revealed that FOD could serve as an effective inhibitor of iron corrosion in 3% NaCl.

The effect of PPY powder on the anticorrosive performance of a duplex cerium/epoxy coating

Polypyrrole powder was chemically synthesized using cerium tartrate as an oxidant. The powder was loaded into an epoxy resin to create a protective coating onto AZ91D Mg alloy. The coatings consisted of an inner cerium-based film and an epoxy layer loaded with different amounts of polypyrrole (0.2–5 wt%) on top. Infrared spectroscopy and Energy Dispersive X-Ray spectroscopy analysis were used to characterize the polymer powder. The anticorrosive properties of the coatings were studied in NaCl containing solution by applying electrochemical measurements such as polarization, electrochemical impedance spectroscopy (EIS), and open circuit potential (OCP). Solution analysis was done to check the electrochemical results obtained. The corrosion resistance was remarkably improved by the addition of the polypyrrole. The best anticorrosive properties were achieved when the epoxy layer was loaded with 1 wt% of PPy. The results show a decrease in corrosion current density from 2.763 × 10-6 to 2.770 × 10-7 mA cm-2 when the polymer was loaded. In addition, the filler reduces the water absorption of the epoxy coating from 9 to 7%. The protective properties were attributed to the barrier behavior of the epoxy film, the corrosion inhibition effect of the PPy, and the self-healing effect of the cerium compounds present in the PPy powder.

Molecular dynamics simulation on the shielding effect of aminopropyl trimethoxysilane film on corrosive media

Aminopropyl trimethoxysilane (APTMS) was used as a silane reagent, and oxygen and water were set as corrosion media, respectively. The mean square displacement (MSD) of oxygen and water molecules in silanized films with different cross-linking degrees (APTMS-OH-1, APTMS-OH-4, APTMS-OH-8, and APTMS-OH-12) were investigated by molecular dynamics simulation to characterize the corrosion inhibition effect of silanized films in different corrosion media. The results showed that compared with in air, the MSD of oxygen and water molecules in silane film was significantly reduced, which indicated that silane film could prevent the diffusion of corrosive medium, thus protecting material. Silane films with various crosslinking degrees have different shielding effects on oxygen and water molecules. The MSD of oxygen in silane films with different crosslinking degrees was: APTMS-OH-1>APTMS-OH-4>APTMS-OH-12>APTMS-OH-8, while the MSD of water in silane films with different crosslinking degrees was: APTMS-OH-1>APTMS-OH-4≈APTMS-OH-12>APTMS-OH-8. The MSD of both oxygen and water molecules was the lowest in silane films with a crosslinking degree of 8, which showed that silane films had the highest shielding effect.

Chitosan/tannic acid phenamine networks-hollow mesoporous silica capsules with reversible pH response: Controlled-releasing amino acid derivatives as “green” corrosion inhibitor

A novel amino acid derivative (SM) was synthesized through Schiff base reaction between syringaldehyde (SA) and methionine (MTI), and loaded to obtain a reversible pH-responsive releasing corrosion inhibitor silica capsule (CS/TA@SM@HMSs) with chitosan/tannic acid phenamine networks on the surface. The corrosion inhibition effect of SM and CS/TA@SM@HMSs on Q235 was studied using electrochemical techniques and surface analysis. The results showed the maximum inhibition efficiency of SM reached to 93.2 % at 200ppm by immersing Q235 in 3.5 wt% NaCl solution. The theoretically calculated electron parameter (the energy gap ΔE = 4.492 eV) indicated that SM molecules were more susceptible to electron transfer with iron surfaces therefore allowing better adsorption on carbon steel surfaces to prevent corrosion. Meanwhile, UV–visible measurements showed that the chitosan/tannic acid phenamine network on the capsule surface responded to changes in pH. The reversible pH-responsive corrosion inhibitor capsule can be switched on and off several times to release SM, demonstrating reversible release and efficient corrosion protection. This study proposes a novel class of “green” amino acid derivative corrosion inhibitors, and establishes a controllable, efficient and reversible pH-responsive release system. A new approach is provided to stimulating the release of corrosion inhibitors in response to long-term corrosion protection of metals.