Review of corrosive environments for copper and its corrosion inhibitors

Adsorption Structures, Vibrational Raman Spectra and Chemical Binding Properties of Thioglycolic Acid on Cu(111) Surfaces: A DFT Study

Copper is widely used in everyday life and industrial production because of its good electrical and thermal conductivity. To overcome copper oxidation and maintain its good physical properties, small organic molecules adsorbed on the surface of copper make a passivated layer to further avoid copper corrosion. In this work, we have investigated thioglycolic acid (TGA, another name is mercaptoacetic acid) adsorbed on copper surfaces by using density functional theory (DFT) calculations and a periodical slab model. We first get five stable adsorption structures, and the binding interaction between TGA and Cu(111) surfaces by using density of states (DOS), indicating that the most stable configuration adopts a triple-end binding model. Then, we analyze the vibrational Raman spectra of TGA adsorbed on the Cu(111) surface and make vibrational assignments according to the vibrational vectors. Finally, we explore the temperature effect of the thermodynamically Gibbs free energy of TGA on the Cu(111) surface and the antioxidant ability of the small organic molecular layer of copper oxidation on the copper surface. Our calculated results further provide evidences to interpret the stability of adsorption structures and antioxidant properties of copper.

Surface Modification of Copper-Based Flakes for Conductive Polymer Composites

The physical properties as well as thermal and electrical stability of copper particles can be improved by surface protection, which mainly depends on the coating material. Our study was, therefore, focused on the rheological, thermal, mechanical and electrical characterization of polymer composites by comparing uncoated (Cu), silver-coated (Cu@Ag) and silica-coated (Cu@Si) copper flakes in low-density polyethylene at various volume concentrations (up to 40%). Interactions among particles were investigated by rheological properties, as these indicate network formation (geometrical entanglement), which is important for mechanical reinforcement as well as establishing an electric pathway (electrical percolation). The results showed that geometrical and electrical percolation were the same for Cu and Cu@Si, ~15%, while, surprisingly, Cu@Ag exhibited much lower percolation, ~7.5%, indicating the fusion of the Ag coating material, which also decreased crystal growth (degree of crystallinity). Furthermore, the magnitude of the rheological and mechanical response remained the same for all investigated materials, indicating that the coating materials do not provide any load transfer capabilities. However, they profoundly affect electron transfer, in that, Cu@Ag exhibited superior conductivity (74.4 S/m) compared to Cu (1.7 × 10-4 S/m) and Cu@Si (1.5 × 10-10 S/m). The results obtained are important for the design of advanced polymer composites for various applications, particularly in electronics where enhanced electrical conductivity is desired.

3,4-Dimethoxy phenyl thiosemicarbazone as an effective corrosion inhibitor of copper under acidic solution: comprehensive experimental, characterization and theoretical investigations

This study investigates the corrosion inhibition potential of 3,4-dimethoxy phenyl thiosemicarbazone (DMPTS) for copper in 1 M hydrochloric acid (HCl) solutions, aiming to disclose the mechanism behind its protective action. Through an integrative methodology encompassing electrochemical analyses-such as weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS)-we quantitatively evaluate the corrosion protection efficacy of DMPTS. It was determined that the optimal concentration of DMPTS markedly boosts the corrosion resistance of copper, achieving an impressive inhibition efficiency of up to 89% at 400 ppm. The formation of a protective layer on the copper surface, a critical aspect of DMPTS's inhibitory action, was characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). These techniques provided empirical evidence of surface morphology modifications and roughness changes, affirming the formation of a protective barrier against corrosion. A significant advancement in our study was the application of Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, which identified chemical adsorption as the definitive mechanism of corrosion inhibition by DMPTS. The ATR-FTIR results explicitly demonstrated the specific interactions between DMPTS molecules and the copper surface, indicative of a robust protective adsorbed layer formation. This mechanistic insight, crucial to understanding the inhibitory process, aligns with the protective efficacy observed in electrochemical and surface analyses. Theoretical support, provided by the Quantum Theory of Atoms in Molecules (QTAIM) and quantum chemical computations, further validated the strong molecular interaction between DMPTS and copper, corroborating the experimental findings. Collectively, this research not only confirms the superior corrosion inhibition performance of DMPTS in an acidic setting but also elucidates the chemical adsorption mechanism as the foundation of its action, offering valuable insights for the development of effective corrosion inhibitors in industrial applications.

Preparation of corrosion inhibitor from natural plant for mild stil immersed in an acidic environmental: experimental and theoretical study

In the present study, the inhibition performance of some medicinal plants (i.e. Yarrow, Wormwood, Maurorum, Marjoram, and Ribes rubrum) was theoretically and experimentally investigated for mild steel immersed in 1M HCl. In this way, the obtained extracts characterized by Fourier transform infrared spectroscopy (FT-IR) and the electrochemical and theoretical techniques were used to study the inhibition mechanisms of the extracts for the immersed electrode in the acidic solution. In addition, the microstructure of the electrode surface immersed in the blank and inhibitor-containing solutions characterized by field emission scanning electron microscopy (FE-SEM), and Violet-visible (UV-Vis) spectroscopy was used to confirm the adsorption of the compounds on the electrode surface. The obtained electrochemical results revealed that the inhibition performance of the green inhibitors increased by increasing their dosage in the electrolyte. In addition, it was proved that Marjoram plant extract possessed the most inhibition efficiency (up to 92%) among the under-studied herbal extracts. Marjoram extract behaved as a mixed-type inhibitor in the hydrochloric acid solution, and the adsorption process of the extract on the steel surface followed the Langmuir adsorption model. Adsorption of the compounds on the steel surface was also studied using density functional theory (DFT), and it was found that the protonated organic compounds in the extract have a high affinity for adsorption on the electrode surface in the acidic solution.

Integrating experimental and theoretical studies in the development of a novel alginate-based bio-composite for copper anticorrosion in 3.5 % NaCl environments

The development of new coatings based on a biopolymer, epichlorohydrin-modified alginate, and alginate-epichlorohydrin-SrTiO3 nanocomposites incorporating SrTiO3 (STO) nanoparticles in the alginate (Alg) matrix (Alg-Ep-STO), has been addressed in this study. Various characterization techniques were employed to analyze the prepared compounds, including X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), as well as surface analysis methods such as Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Furthermore, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) methods were used to evaluate corrosion inhibition and protection durability. The results demonstrate that the incorporation of STO nanoparticles into the alginate matrix with epichlorohydrin significantly improved the metal's resistance to corrosion. The experimental findings received reinforcement from various computational methods, including density functional theory (DFT), Molecular Dynamics (MD) and Monte Carlo (MC) simulations, which were employed to investigate the interactions between the Alg-Ep-STO nanocomposite and the copper surface. The computational outcomes revealed that the Alg-Ep-STO nanocomposite exhibits robust adhesion to the copper surface, maintaining a flat orientation, with its alignment being notably influenced by the presence of STO nanoparticles.

A novel ventriculoperitoneal shunt flow sensor based on electrically induced spatial variation in cerebrospinal fluid charge density

Introduction: Ventriculoperitoneal (VP) shunts divert cerebrospinal fluid (CSF) out of cerebral ventricles in patients with hydrocephalus or elevated intracranial pressure (ICP). Despite high failure rates, there exist limited clinically viable solutions for long-term and continuous outpatient monitoring of CSF flow rate through VP shunts. We present a novel, low-power method for sensing analog CSF flow rate through a VP shunt premised on induced spatial electrical charge variation. Methods: Two geometric variants of the proposed sensing mechanism were prototyped: linear wire (P1) and cylindrical (P2) electrodes. Normal saline was gravity-driven through P1 and a commercially available shunt system in series. True flow rates were measured using a high-precision analytical balance. Subsequently, artificial CSF was driven by a programmable syringe pump through P2. Flow rate prediction models were empirically derived and tested. Sensor response was also assessed during simulated obstruction trials. Finally, power consumption per flow measurement was measured. Results: P1 (17 mm long) and P2 (22 mm long) averaged 7.2% and 4.2% error, respectively, in flow rate measurement from 0.01 to 0.90 mL/min. Response curves exhibited an appreciably flattened profile during obstruction trials compared to non-obstructed states. P2 consumed 37.5 µJoules per flow measurement. Conclusion: We propose a novel method for accurately sensing CSF flow rate through a VP shunt and validate this method at the benchtop with normal saline and artificial CSF over a board range of flows (0.01-0.90 mL/min). The sensing element is highly power efficient, compact, insertable into existing shunt and valve assemblies, and does not alter CSF flow mechanics.

Sulfonated Zinc Phthalocyanine Coating as an Efficient and Ecofriendly Corrosion Inhibitor for Copper Surfaces: An In Silico Led Design and Its Experimental Validation

The current study highlights the successful integration of an in silico design with experimental validation to create a highly effective corrosion inhibitor for copper (Cu) surfaces. The synthesized sulfonated zinc phthalocyanine (Zn-Pc) is electrochemically characterized and demonstrates an impressive 97% inhibition efficiency, comparable to the widely used industrial corrosion inhibitor, BTA, for Cu surfaces. The corrosion inhibition is comprehensively analyzed through potentiodynamic polarization and impedance spectroscopy techniques, supported by their respective equivalent circuits. Furthermore, the sample undergoes thorough characterization using scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, contact angle measurements, and atomic force microscopy. Density functional theory calculations reveal that sulfonated Zn-Pc exhibits the highest interaction energy, underscoring its exceptional inhibition properties. These results open possibilities for utilizing computational methods to design and optimize corrosion inhibitors for protection of Cu surfaces.

Effect of benzotriazole on the existing pits of copper tube in fire sprinkler system

In this paper, two leaking tubes were investigated among copper tubes injected with 200 and 400 ppm benzotriazole after 8 years of usage. The electrochemical tests were conducted in simulated pit-out and pit-in environments (i.e., regions outside and inside of the pit) to determine the effect of benzotriazole on the propagation of an existing pit. The electrochemical analysis results showed that 200 and 400 ppm benzotriazole exhibit relatively lower inhibition efficiency in an acidic simulated pit-in environment because of the difficulty of forming a protective film and the benzotriazole cationization.

Copper corrosion prevention in 3.5% NaCl solution by Spartium junceum petals extract as an eco-friendly bio-inhibitor: kinetic and thermodynamic studies

During the last decades, numerous studies were performed to introduce green corrosion inhibitors. So, various materials were utilized due to their being bio-degradable, available, and inexpensive. Because of the aforementioned aspects, Spartium Junceum petals extract (SJPE) was used as a new bio-inhibitor for the prevention of copper corrosion in a 3.5 wt% NaCl solution. This extract was obtained in water as a non-toxic solvent. Also, gas chromatography-mass spectrometry (GC-MS) confirmed the presence of organic molecules containing O, N, and F heteroatoms in SJPE, which are important for inhibitors. Also, Fourier-transform infrared spectroscopy (FT-IR) was used to identify the functional groups of the inhibitor molecules. Moreover, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used which verified the great effect of this procedure to promote resistance corrosion of copper substrate. In addition, scanning electron microscopy (SEM) exhibited the surface morphology of copper substrate in the presence of SJPE which demonstrated the improvement of corrosion resistance in comparison to the absence of this bio-inhibitor. It should be noted that by increasing the amount of SJPE, the inhibition efficiency was ameliorated up to 87.8%. Furthermore, variation in temperature magnitude between 298 and 338 K implied that SPJE can improve inhibition behavior in higher temperatures. By applying temperature effect study data, the value of activation energy in the presence of the inhibitor was calculated (37.9 kJ mol-1), and the adsorption isotherm was Langmuir. Also, these data showed the inhibition mechanism is physical adsorption. The proposed inhibitor can be used as an efficient, eco-friendly, and inexpensive bio-inhibitor for the prevention of copper corrosion.

Combination of practical and theoretical measurements of albumin egg as an eco-friendly inhibitor for copper corrosion in alkaline solutions

Utilizing environmentally acceptable substances as inhibitors of metal corrosion is one of the most important strategies to reduce corrosion. In alkaline solutions (1.0 M KOH), the influence of albumin egg as a green corrosion inhibitor for copper was studied via a mix of experimental and theoretical investigations. Cyclic voltammetry (CV), open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), AFM, and SEM/EDX methods were all utilized to examine the inhibitory effect of albumin egg. By increasing the amount of albumin egg in the corrosive solution, the inhibition efficiency is increased. The albumin egg is a highly effective cathodic type inhibitor, according to electrochemical tests, with an inhibition efficiency of up to 94%. It also follows the Langmuir isotherm during adsorption. Investigations using SEM/EDX and AFM show that the albumin egg can create an adsorption layer on the surface enabling the shielding of the copper surface from harmful ions. In order to better understand the molecular structure of the albumin egg and its inhibitory action against corrosion, computational and molecular dynamics simulation techniques were also employed for calculating the electronic characteristics of inhibitor molecules. Calculations were made for total energy (TE), change in total energy (DET), energy gap (ΔE), ELUMO, EHOMO, dipole moment (D), and softness (δ). Utilizing the Monte Carlo simulation, the mechanism of albumin egg adsorption on the surface of Cu was investigated. The theoretical outcomes were found to confirm the empirical results.

The influence of calcium on copper corrosion and its by-product release in drinking water

Copper is a high-quality material commonly used in drinking water supply pipes. Calcium is a prevalent cation found in drinking water. However, the effects of calcium on copper corrosion and its by-product release remain unclear. This study discusses the influences of Ca²⁺ on copper corrosion and its by-product release in drinking water under different conditions of Cl^-, SO₄^2-, and Cl^-/SO₄^2-, using electrochemical and scanning electron microscopy techniques. The results indicate that Ca²⁺ slows down the corrosion reaction of copper to some extent in comparison with Cl^-, and the E_corr shifts positively by 0.022 V, while I_corr decreases by 0.235 μA cm^-2. However, the by-product release rate increases by 0.5 μg cm^-2. The addition of Ca²⁺ causes the anodic process to become the controlling factor for corrosion, with an increase in resistance observed in both the inner and outer layers of the corrosion product film through SEM analysis. The corrosion product film becomes denser due to the reaction between Ca²⁺ and Cl^-, forming a product that inhibits the entry of Cl^- into the passive film on the copper surface. Adding Ca²⁺ promotes copper corrosion with the help of SO₄^2- and the release of corrosion by-products. The anodic reaction resistance decreases while the cathodic reaction resistance increases, resulting in a small potential difference of only 10 mV between the anode and cathode. The resistance of the inner layer film decreases, while that of the outer layer film increases. SEM analysis shows that the surface becomes rougher with the addition of Ca²⁺, and 1-4 mm granular corrosion products are formed. This is due to the fact that Cu₄(OH)₆SO₄ has low solubility and forms a relatively dense passive film that inhibits the corrosion reaction. The added Ca²⁺ also reacts with SO₄^2- to form CaSO₄, which reduces the amount of Cu₄(OH)₆SO₄ generated at the interface, thus damaging the integrity of the passive film. Adding Ca²⁺ promotes the corrosion of copper by Cl^- and SO₄^2- and enhances the release of corrosion by-products, with the highest corrosion rate observed under the Cl^-/SO₄^2-/Ca²⁺ conditions. The resistance of the inner layer membrane decreases, while the mass transfer resistance of the outer layer membrane increases. Under the Cl^-/SO₄^2- conditions, the SEM surface of the Cu₂O particles is uniform in size, arranged in an orderly and compact manner. After adding Ca²⁺, the size of the particles becomes uneven, and the surface becomes rough and uneven. This is because Ca²⁺ firstly combines with SO₄^2-, thus promoting corrosion. And then the remaining Ca²⁺ combines with Cl^-, which inhibits corrosion. Despite the amount of remaining Ca²⁺ being small, it still promotes corrosion. The amount of released corrosion by-products is mainly controlled by the redeposition reaction that occurs in the outer layer membrane, determining the amount of Cu₂O to which the copper ions are converted. The increase in resistance of the outer layer membrane means that the charge transfer resistance of the redeposition reaction increases, and the reaction rate slows down. Consequently, the amount of Cu(ii) converted to Cu₂O decreases, leading to an increase in Cu(ii) in the solution. Therefore, adding Ca²⁺ in all three conditions results in an increase in the release of corrosion by-products.

Prevention of surface colonization and anti-biofilm effect of selected phytochemicals against Listeria innocua strain

This work aimed to determine the ability of Listeria innocua (L.i.) to colonize eight materials found in food-processing and packaging settings and to evaluate the viability of the sessile cells. We also selected four commonly used phytochemicals (trans-cinnamaldehyde, eugenol, citronellol, and terpineol) to examine and compare their efficacies against L.i. on each surface. Biofilms were also deciphered in chamber slides using confocal laser scanning microscopy to learn more about how phytochemicals affect L.i. The materials tested were silicone rubber (Si), polyurethane (PU), polypropylene (PP), polytetrafluoroethylene (PTFE), stainless steel 316 L (SS), copper (Cu), polyethylene terephthalate (PET), and borosilicate glass (GL). L.i. colonized Si and SS abundantly, followed by PU, PP, Cu, PET, GL, and PTFE surfaces. The live/dead status ranged from 65/35% for Si to 20/80% for Cu, and the estimates of cells unable to grow on Cu were the highest, reaching even 43%. Cu was also characterized by the highest degree of hydrophobicity (ΔG^TOT = -81.5 mJ/m²). Eventually, it was less prone to attachment, as we could not recover L.i. after treatments with control or phytochemical solutions. The PTFE surface demonstrated the least total cell densities and fewer live cells (31%) as compared to Si (65%) or SS (nearly 60%). It also scored high in hydrophobicity degree (ΔG^TOT = -68.9 mJ/m²) and efficacy of phytochemical treatments (on average, biofilms were reduced by 2.1 log₁₀ CFU/cm²). Thus, the hydrophobicity of surface materials plays a role in cell viability, biofilm formation, and then biofilm control and could be the prevailing parameter when designing preventive measures and interventions. As for phytochemical comparison, trans-cinnamaldehyde displayed greater efficacies, with the highest reductions seen on PET and Si (4.6 and 4.0 log₁₀ CFU/cm²). The biofilms in chamber slides exposed to trans-cinnamaldehyde revealed the disrupted organization to a greater extent than other molecules. This may help establish better interventions via proper phytochemical selection for incorporation in environment-friendly disinfection approaches.

Recent Progress of Polymeric Corrosion Inhibitor: Structure and Application

An anti-corrosion inhibitor is one of the most useful methods to prevent metal corrosion toward different media. In comparison with small molecular inhibitors, a polymeric inhibitor can integrate more adsorption groups and generate a synergetic effect, which has been widely used in industry and become a hot topic in academic research. Generally, both natural polymer-based inhibitors and synthetic polymeric inhibitors have been developed. Herein, we summarize the recent progress of polymeric inhibitors during the last decade, especially the structure design and application of synthetic polymeric inhibitor and related hybrid/composite.

Application of Biomass Corrosion Inhibitors in Metal Corrosion Control: A Review

Corrosion is the process of damaging materials, and corrosion of metallic materials frequently results in serious consequences. The addition of corrosion inhibitors is the most effective means of preventing metal corrosion. Until now, researchers have made unremitting efforts in the research of high-efficiency green corrosion inhibitors, and research on biomass corrosion inhibitors in a class of environmentally friendly corrosion inhibitors is currently quite promising. This work presents the classification of green biomass corrosion inhibitors in detail, including plant-based corrosion inhibitors, amino acid corrosion inhibitors, and biosurfactant corrosion inhibitors, based on the advantages of easy preparation, environmental friendliness, high corrosion inhibition efficiency, and a wide application range of biomass corrosion inhibitors. This work also introduces the preparation methods of biomass corrosion inhibitors, including hydrolysis, enzymatic digestion, the heating reflux method, and microwave extraction. In addition, the corrosion inhibition mechanisms of green biomass corrosion inhibitors, including physical adsorption, chemisorption, and film-forming adsorption, and evaluation methods of biomass corrosion inhibitors are also explicitly described. This study provides valuable insights into the development of green corrosion inhibitors.

Feasibility of Carbon Nanoparticle Coatings as Protective Barriers for Copper─Wetting Assessment

Copper is extensively used in a wide range of industrial and daily-life applications, varying from heat exchangers to electrical wiring. Although it is protected from oxidation by its native oxide layer, when subjected to harsh environmental conditions─such as in coastal regions─this metal can rapidly degrade. Therefore, in this study, we analyze the potential use of carbon nanoparticle coatings as protective barriers due to their intrinsic hydrophobic wetting behavior. The nanocarbon coatings were produced via electrophoretic deposition on Cu platelets and characterized via scanning electron microscopy, confocal laser scanning microscopy, and sessile drop test; the latter being the primary focus since it provides insights into the wetting behavior of the produced coatings. Among the measured coatings, graphite flakes, graphene oxide, and carbon nanotube (CNT) coatings showed superhydrophobic behavior. Based on their wetting behavior, and specifically for electrical applications, CNT coatings showed the most promising results since these coatings do not significantly impact the substrate's electrical conductivity. Although CNT agglomerates do not affect the wetting behavior of the attained coatings, the coating's thickness plays an important role. Therefore, to completely coat the substrate, the CNT coating should be sufficiently thick─above approximately 1 μm.

Copper inks for printed electronics: a review

Conductive inks have attracted tremendous attention owing to their adaptability and the convenient large-scale fabrication. As a new type of conductive ink, copper-based ink is considered to be one of the best candidate materials for the conductive layer in flexible printed electronics owing to its high conductivity and low price, and suitability for large-scale manufacturing processes. Recently, tremendous progress has been made in the preparation of cooper-based inks for electronic applications, but the antioxidation ability of copper-based nanomaterials within inks or films, that is, long-term reliability upon exposure to water and oxygen, still needs more exploration. In this review, we present a comprehensive overview of copper inks for printed electronics from ink preparation, printing methods and sintering, to antioxidation strategies and electronic applications. The review begins with an overview of the development of copper inks, followed by a demonstration of various preparation methods for copper inks. Then, the diverse printing techniques and post-annealing strategies used to fabricate conductive copper patterns are discussed. In addition, antioxidation strategies utilized to stabilize the mechanical and electrical properties of copper nanomaterials are summarized. Then the diverse applications of copper inks for electronic devices, such as transparent conductive electrodes, sensors, optoelectronic devices, and thin-film transistors, are discussed. Finally, the future development of copper-based inks and the challenges of their application in printed electronics are discussed.

Computational Foretelling and Experimental Implementation of the Performance of Polyacrylic Acid and Polyacrylamide Polymers as Eco-Friendly Corrosion Inhibitors for Copper in Nitric Acid

Copper is primarily used in many industrial processes, but like many other metals, it suffers from corrosion damage. Polymers are not only one of the effective corrosion inhibitors but also are environmentally friendly agents in doing so. Hence, in this paper, the efficacy of two polyelectrolyte polymers, namely poly(acrylic acid) (PAA) and polyacrylamide (PAM), as corrosion inhibitors for copper in molar nitric acid medium was explored. Chemical, electrochemical, and microscopic tools were employed in this investigation. The weight-loss study revealed that the computed inhibition efficiencies (% IEs) of both PAA and PAM increased with their concentrations but diminished with increasing HNO₃ concentration and temperature. The results revealed that, at similar concentrations, the values of % IEs of PAM are slightly higher than those recorded for PAA, where these values at 298 K reached 88% and 84% in the presence of a 250 mg/L of PAM and PAA, respectively. The prominent IE% values for the tested polymers are due to their strong adsorption on the Cu surface and follow the Langmuir adsorption isoform. Thermodynamic and kinetic parameters were also calculated and discussed. The kinetics of corrosion inhibition by PAA and PAM showed a negative first-order process. The results showed also that the used polymers played as mixed-kind inhibitors with anodic priority. The mechanisms of copper corrosion in nitric acid medium and its inhibition by the tested polymers were discussed. DFT calculations and molecular dynamic (MD) modelling were used to investigate the effect of PAA and PAM molecular configuration on their anti-corrosion behavior. The results indicated that the experimental and computational study are highly consistent.

A study on synergistic effect of chloride and sulfate ions on copper corrosion by using electrochemical noise in asymmetric cells

The current study includes a systematic examination of copper corrosion initially in each of NaCl and Na₂SO₄ solutions separately and then in the mixture solution of Cl⁻ and SO₄²⁻ ions as aggressive ions. Electrochemical current noise (ECN) signals resulting from asymmetric (Asy) as well as symmetric (Sym) cells have been interpreted using wavelet transform (WT) along with statistical procedures. The signals have been detrended and the decomposition of every signal has been carried out into 8 crystals. Then the standard deviation of every crystal has been illustrated with the standard deviation of partial signal (SDPS) plots. The Asy electrodes increased the pitting detection on copper compared with the Sym ones, indicating higher efficiency of the Asy electrodes. Asymmetric-copper electrodes have been studied using SDPS plots at different temperatures (40, 60, as well as 80 °C). Finally, in order to partly understand the effect of Cl⁻ and SO₄²⁻ ions on the corrosion of copper, the stabilization of Cu²⁺ cations by Cl⁻ and SO₄²⁻ ions in aqueous solutions have been modeled by DFT calculations. The derived results are in accordance with the experimental data.

Important Explorations on Surface Corrosion of the Copper Coins Sourced from the Qing Dynasty

Surface corrosion is considered to be a main reason for the surface pattern damages of copper coin sourced from the Qing Dynasty. In this study, micromorphology and the structural feature of the copper coins were analyzed to determine their corrosion mechanisms. The results revealed that the etching rates successively reduced with decreasing corrosion thickness, possibly because of unique macrofeatures of the surface pattern. Variable phases, bonding morphologies, and three-/two-dimensional structures of Ql-TB (Qianlong-Tongbao) coins were visibly different at the microscale, which induced disproportional stresses and microscopic cracks, facilitating an unhindered entry of oxide and hydroxyl (OH^-) ions. These species resulted in the competitive interplay of self-healing and self-degradation mechanisms on the coin surfaces and formed corrosion thickness of ~9.31 μm and a mean corrosion rate of ~2.7%. This study provided an important guideline for preserving microstructures and surface patterns of historical copper coins.

Rising of MXenes: Novel 2D-functionalized nanomaterials as a new milestone in corrosion science - a critical review

Corrosion is a natural process between a metal and its environment that can gradually cause catastrophic damage to the metal equipment, which would have economic implications. Consequently, several protective methods have been utilized to prevent metals from severe degradation. Organic polymeric coatings have been widely used as the most convenient and cost-effective method to boost metals' anti-corrosion properties. Nonetheless, these coatings have a significant amount of solvent, resulting in shrinkage and micro defects in the films during the curing process. Many studies have verified that transition metal carbides/nitrides (MXenes) can form a "labyrinth effect" in the polymeric coatings due to their "nano-barrier effect". Furthermore, based on their sheet-like structures, they can considerably cover the surface defects of the polymeric films. Therefore, the penetration of corrosive elements can be substantially curbed. It is the first review that specifically focused on the new family of 2D nanomaterials, i.e., MXenes, and discussed their applications in corrosion protection systems. The MXenes' pros and cons in the polymeric matrixes as nanofillers will be clarified. Moreover, the synthesis and functionalization methods of the MXenes, their applications, and corrosion protection mechanism will be explored. Subsequently, the MXenes' superiority over other 2D nanomaterials will be highlighted while their future perspectives and industrial applications will be predicted.

Anticorrosion Study for Brass Alloys in Heat Exchangers during Acid Cleaning Using Novel Gemini Surfactants Based on Benzalkonium Tetrafluoroborate

For a variety of applications, the brass alloy has been utilized to replace titanium tubes in heat exchangers. Copper alloys' high corrosion rate during the acid cleaning procedure remains a significant concern. To inhibit the corrosion of brass alloys, we prepared two novel gemini surfactants (GSs), N ₁,N ₃-dibenzyl-N ₁,N ₁,N ₃,N ₃-tetramethylpropane-1,3-diaminium tetrafluoroborate (I H) and N ₁,N ₁,N ₃,N ₃-tetramethyl-N ₁,N ₃-bis (4-methyl benzyl) propane-1,3-diaminium tetrafluoroborate (I Me), and they were characterized using Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance spectroscopy. Their inhibition performance against corrosion of brass alloys in 1 M HCl was studied using electrochemical techniques including potentiodynamic polarization (PP), electrochemical impedance spectroscopy, and electrochemical frequency modulation. The inhibition effect of the synthesized compounds was high, and it increased as the inhibitor's concentration was increased. The maximum level of inhibition efficiency was achieved at an inhibitor concentration of 100 ppm, reaching 96.42% according to PP measurements. From Langmuir data, the mechanisms of adsorption of the two GSs on the surface of copper was found to be physisorption and chemisorption adsorption. X-ray photoelectron spectroscopy and scanning electron microscopy show that the addition of the two compounds lowers the dissolution of brass ions in the corrosive solution and forms a protective layer on the surface of the brass.

A General Use QSAR-ARX Model to Predict the Corrosion Inhibition Efficiency of Drugs in Terms of Quantum Mechanical Descriptors and Experimental Comparison for Lidocaine

A study of 250 commercial drugs to act as corrosion inhibitors on steel has been developed by applying the quantitative structure-activity relationship (QSAR) paradigm. Hard-soft acid-base (HSAB) descriptors were used to establish a mathematical model to predict the corrosion inhibition efficiency (IE%) of several commercial drugs on steel surfaces. These descriptors were calculated through third-order density-functional tight binding (DFTB) methods. The mathematical modeling was carried out through autoregressive with exogenous inputs (ARX) framework and tested by fivefold cross-validation. Another set of drugs was used as an external validation, obtaining SD, RMSE, and MSE, obtaining 6.76%, 3.89%, 7.03%, and 49.47%, respectively. With a predicted value of IE% = 87.51%, lidocaine was selected to perform a final comparison with experimental results. By the first time, this drug obtained a maximum IE%, determined experimentally by electrochemical impedance spectroscopy measurements at 100 ppm concentration, of about 92.5%, which stands within limits of 1 SD from the predicted ARX model value. From the qualitative perspective, several potential trends have emerged from the estimated values. Among them, macrolides, alkaloids from Rauwolfia species, cephalosporin, and rifamycin antibiotics are expected to exhibit high IE% on steel surfaces. Additionally, IE% increases as the energy of HOMO decreases. The highest efficiency is obtained in case of the molecules with the highest ω and ΔN values. The most efficient drugs are found with pK_a ranging from 1.70 to 9.46. The drugs recurrently exhibit aromatic rings, carbonyl, and hydroxyl groups with the highest IE% values.

Recycling Unused Midazolam Drug as Efficient Corrosion Inhibitor for Copper in Nitric Acid Solution

The current work explores the potential for recycling unused or expired Midazolam (MID) drug, a benzodiazepine derivative, as an efficient corrosion inhibitor for copper in nitric acid solution. The technical advantage of recycling expired MID drug relates to the avoidance of organic inhibitor production costs and the reduction of disposal costs of the expired medication. A combination of electrochemical methods (potentiodynamic polarization and electrochemical impedance spectroscopy), weight loss, and quantum chemical calculation were used to assess the inhibition mechanism and efficiency of MID. It was found that inhibition efficiency increases with inhibitor concentration, reaching a highest value of 92.9% for a concentration of 10⁻⁴ M MID. MID was classified as a mixed-type inhibitor, showing a preferential cathodic suppression mechanism. The obtained values of −45.89 kJ mol⁻¹ for the standard free energy of adsorption indicate that the inhibition mechanism is based on chemisorption of MID molecules on the copper surface, which obeys the Langmuir isotherm. Surface analysis using scanning electronic microscopy revealed that MID offers high protection against corrosion during both immersion and polarization tests. Molecular modelling and quantum chemical calculations indicated chemical interactions between MID molecules and the copper surface, as well as electrostatic interactions. The results obtained using the different techniques were in good agreement and highlight the effectiveness of MID in the corrosion inhibition of copper.

Use of Time Domain Nuclear Magnetic Resonance Relaxometry to Monitor the Effect of Magnetic Field on the Copper Corrosion Rate in Real Time

The corrosion of metals is a major problem of modern societies, demanding new technologies and studies to understand and minimize it. Here we evaluated the effect of a magnetic field (B) on the corrosion of copper in aqueous HCl solution under open circuit potential. The corrosion product, Cu2+, is a paramagnetic ion and its concentration in the solution was determined in real time in the corrosion cell by time-domain NMR relaxometry. The results show that the magnetic field (B = 0.23 T) of the time-domain NMR instrument reduces the corrosion rate by almost 50%, in comparison to when the corrosion reaction is performed in the absence of B. Atomic force microscopy and X-ray diffraction results of the analysis of the corroded surfaces reveal a detectable CuCl phase and an altered morphology when B is present. The protective effect of B was explained by magnetic forces that maintain the Cu2+ in the solution/metal interface for a longer time, hindering the arrival of the new corrosive agents, and leading to the formation of a CuCl phase, which may contribute to the rougher surface. The time-domain NMR method proved to be useful to study the effect of B in the corrosion of other metals or other corrosive liquid media when the reactions produce or consume paramagnetic ions.

Extracellular Electron Transfer by Pseudomonas aeruginosa in Biocorrosion: A Review

Microorganisms with extracellular electron transfer (EET) capability have gained significant attention for their different biotechnological applications, like biosensors, bioremediation, and microbial fuel cells. Current research affirmed that microbial EET potentially promotes corrosion of iron structures, termed microbiologically influenced corrosion (MIC). The sulfate-reducing (SRB) and nitrate-reducing (NRB) bacteria are the most investigated among the different MIC-promoting bacteria. Unlike extensively studied SRB corrosion, NRB corrosion has received less attention from researchers. Hence, this review focuses on EET by Pseudomonas aeruginosa, a pervasive bacterium competent for developing biofilms in marine habitats and oil pipelines. A comprehensive discussion on the fundamentals of EET mechanisms in MIC is provided first. After that, the review offers state-of-the-art insights into the latest research on the EET-assisted MIC by Pseudomonas aeruginosa. The role of electron transfer mediators has also been discussed to understand the mechanisms involved in a better way. This review will be beneficial to open up new opportunities for developing strategies for combating biocorrosion.

Pure Alloy Additive or Preliminary Alloy: A Comparative Study on Obtaining High-Strength Copper Magnesium Alloys Designed for Electrical Power Systems

Due to the increasing demand for electrical energy in modern society, there is a huge requirement for conducting materials and, due to the development of electromobility, this demand is forecasted to grow each year. This is one of the reasons why copper and copper alloys manufacturing and processing industries tend to evolve and improve. One of the improvement paths is the design of new conducting materials for electrical power systems, electrical energy transmission, and energy storage systems. This paper presents a comparative study on obtaining high-strength copper magnesium alloys in terms of the alloy additive used during the metallurgical synthesis process, because this is a crucial, initial element in obtaining the final conducting product, such as wires. The obtained ingots were tested in terms of their chemical composition, and mechanical and physical properties. The provided results prove that there is a significant increase in the materials’ hardness (and thus the ultimate tensile strength), and a slight decrease in density, impact resistance, and electrical conductivity, as the Mg content increases. Scanning electron microscopy (SEM) and phase analysis were additionally conducted in order to determine the distribution and origin of Mg precipitations. Collectively, the results show that the CuMg alloys may successfully replace other alloys, such as CuNiSi or CuZn, as carrying and conducting materials because their properties are superior to those of the aforementioned materials.

Organic Compounds as Corrosion Inhibitors for Carbon Steel in HCl Solution: A Comprehensive Review

Most studies on the corrosion inhibition performance of organic molecules and (nano)materials were conducted within “carbon steel/1.0 M HCl” solution system using similar experimental and theoretical methods. As such, the numerous research findings in this system are sufficient to conduct comparative studies to select the best-suited inhibitor type that generally refers to a type of inhibitor with low concentration/high inhibition efficiency, nontoxic properties, and a simple and cost-economic synthesis process. Before data collection, to help readers have a clear understanding of some crucial elements for the evaluation of corrosion inhibition performance, we introduced the mainstay of corrosion inhibitors studies involved, including the corrosion and inhibition mechanism of carbon steel/HCl solution systems, evaluation methods of corrosion inhibition efficiency, adsorption isotherm models, adsorption thermodynamic parameters QC calculations, MD/MC simulations, and the main characterization techniques used. In the classification and statistical analysis section, organic compounds or (nano)materials as corrosion inhibitors were classified into six types according to their molecular structural characteristics, molecular size, and compound source, including drug molecules, ionic liquids, surfactants, plant extracts, polymers, and polymeric nanoparticles. We outlined the important conclusions obtained from recent literature and listed the evaluation methods, characterization techniques, and contrastable experimental data of these types of inhibitors when used for carbon steel corrosion in 1.0 M HCl solution. Finally, statistical analysis was only performed based on these data from carbon steel/1.0 M HCl solution system, from which some conclusions can contribute to reducing the workload of the acquisition of useful information and provide some reference directions for the development of new corrosion inhibitors.

Chloride-Assisted Corrosion of Copper and Protection by Benzotriazole

The structure and composition of copper surfaces in aqueous solutions of benzotriazole (BTAH) and NaCl was investigated by sum frequency vibrational spectroscopy as a function of concentration and bias during cyclic voltammetry experiments. We found that the protection provided by the BTAH films formed at the copper surface is effective for negative bias voltages below the open circuit potential (OCP) but not at positive voltages where Cl^- displaces BTAH. By measuring the Gibbs adsorption energy of BTAH and Cl^-, we found that a particularly stable Cl^- structure is formed around the OCP, suggesting that electronegative additives that move the OCP to higher negative values can improve BTAH protection, which we confirmed by the addition of a negatively charged sodium dodecyl sulfate surfactant.

A review on recent advances in electrodeionization for various environmental applications

The growing contamination of ecosystems necessitates the development of long-term pollution-removal technologies. Electrodeionization, in notably, has newly proven as an efficient method for removing ionic chemicals from polluted waterways. The fact that continuous electrodeionization is a greener technique is most probably the biggest cause for its success. It replaces the toxic chemicals typically required to replenish resins with electric power, therefore eliminating the wastewater involved with resin renewal. In water treatment, electrodeionization solves some of the drawbacks of ion exchange resin beds, particularly ion dumping as beds expire. This comprehensive review explores the theory, principles, and mechanisms of ion movement and separation in an electrodeionization unit. Also, it investigated the construction and usage, notably in removing heavy metal and its current developments in electrodeionization unit. Recent advances in Electrodeionization like polarity reversal, Resin wafer Electrodeionization, membrane free Electrodeionization, and electrostatic shielding with novel materials and hybrid process along with Electrodeionization were addressed. Further advancements are expected in electrodeionization systems that exhibit better efficacy while running at lower costs due to decreased energy usage, rendering them appealing for industrial scale up across a wide range of applications across the world.

Thin Protective Coatings on Metals Formed by Organic Corrosion Inhibitors in Neutral Media

Protection of metals in neutral media with pH 5.0–9.0 (in humid atmospheres and various aqueous solutions) can be achieved by formation of thin coatings (up to several tens of nm) on their surfaces due to adsorption and more complex chemical interactions of organic corrosion inhibitors (OCIs) with the metal to be protected. The review contains three sections. The first section deals with coatings formed in aqueous solutions, while the second one, with those formed in organic and water-organic solvents. Here we consider metal protection by coatings mainly formed by the best-known classes of OCI (carboxylates, organophosphates and phosphonates) and estimation of its efficiency. The third section discusses the peculiarities of protection of metals in the vapor-gas phase, i.e., by volatile OCIs, and a relatively new type of metal protection against atmospheric corrosion by the so-called chamber inhibitors. OCIs with relatively low volatility under normal conditions can be used as chamber OCIs. To obtain a protective coating on the surfaces of metal items, they are placed in a chamber inside which an increased concentration of vapors of a chamber OCI is maintained by increasing the temperature. This review mainly focuses on the protection of iron, steels, copper and zinc.