Understanding functional group effect on corrosion inhibition efficiency of selected organic compounds

Investigating the effectiveness of an imidazopyridine-based compound as an anti-corrosive additive for mild steel in molar hydrochloric acid solutions: a mutual multi-facet experimental and computational approach

The use of effective, environmentally friendly inhibitors is a promising strategy to mitigate metallic corrosion. This work involved the development of a new imidazopyridine-based compound (i.e., MPPIP) and an assessment of its effectiveness as an anti-corrosive entity for the mild steel metal (MS) in 1.00 M hydrochloric acid medium. The compound's performance was evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), which demonstrated that MPPIP achieves 98% inhibition efficiency with 10-3 M concentration at room temperature. The electrochemical analysis confirmed that MPPIP acts as a mixed-type inhibitor, reducing both anodic and cathodic reactions. Thermodynamic analyses revealed that MPPIP adsorption follows Langmuir's isotherm, involving a combination of physisorption and chemisorption mechanisms. Additional validation was performed using UV-Vis spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), which revealed a uniform protective film on the steel surface, preventing metal dissolution. Computational approaches, including density functional theory (DFT) and Monte Carlo simulations, highlighted the molecule's high electron-donating ability and strong adsorption energy, confirming its strong interaction with the metal surface. These findings demonstrate that MPPIP is a promising and efficient corrosion inhibitor for mild steel in acidic environments with inexpensive and easily synthesized route characteristics.

Sustainable technology for cultural heritage preservation: The role of green corrosion inhibitors

The preservation of metallic artefacts in cultural heritage necessitates effective corrosion control strategies to ensure structural stability and aesthetic integrity. Conventional synthetic corrosion inhibitors, while demonstrating high efficacy, present significant environmental and health concerns due to their inherent toxicity. Consequently, sustainable, plant-derived corrosion inhibitors have emerged as promising alternatives, offering comparable protective performance with reduced ecological impact. This review examines the potential of plant extracts as environmentally benign corrosion inhibitors, highlighting their diverse phytochemical constituents-including tannins, alkaloids, and amino acids-which exhibit functional similarity to synthetic organic inhibitors in electronic structure and adsorption mechanisms. These bioactive compounds mitigate corrosion through adsorption, leading to the formation of protective passive layers that hinder oxidation reactions and restrict electrochemical degradation. For instance, tannic acid reacts with iron to form ferric tannates, generating a stable barrier against aggressive electrolytes. Similarly, extracts from Ceratonia siliqua and Brassica campestris have demonstrated notable corrosion inhibition for copper alloys and Cor-Ten steel, respectively. The efficacy of these plant-derived inhibitors is commonly assessed using electrochemical techniques, particularly electrochemical impedance spectroscopy (EIS), where an increase in charge-transfer resistance (Rct) and a reduction in double-layer capacitance (Cdl) indicate enhanced corrosion protection. This study presents a comprehensive evaluation of the mechanisms, performance, and applicability of green corrosion inhibitors in metallic heritage conservation, with case studies demonstrating their successful implementation in preservation efforts. Furthermore, key challenges such as optimizing inhibitor concentrations, managing temperature sensitivity, and ensuring long-term stability are critically analyzed. Additionally, various inhibitor application methods are explored along with practical considerations for scaling up and integrating green inhibitors into conservation workflows. Additionally, a comparative analysis of conventional and sustainable inhibitors in real-world applications is presented. The review concludes by highlighting key research gaps and proposing future directions for advancing plant-based corrosion inhibitor technologies in heritage conservation. Through this analysis, it seeks to enhance the understanding and adoption of sustainable corrosion mitigation strategies for preserving metallic cultural artefacts.

Polypyridyl-based bridging corrosion inhibitors: A critical review on interface and ligands properties

The ligand characteristics of polypyridyls, primarily bipyridine (bipy), phenanthroline (Phen), terpyridine (Tpy), naphthyridine (NC), and their derivatives, are popular for their ability to create stable chelating complexes with metal ions. Because of these characteristics, they and their coordination complexes have been used for many purposes. Polypyridyl-based heterocycles have been widely employed as corrosion inhibitors in the aqueous phase as they provide long-lasting, consistent and efficient protection. The unshared nitrogen electron pairs in polypyridyl-based corrosion inhibitors significantly coordinate with the metal substrates. Corrosion inhibitors based on polypyridyls increase polarization or charge transfer resistance (Rp or Rct) and decrease corrosion current density (icorr) by blocking active sites. Their adsorption, coordination, and chelation are thermodynamically advantageous due to their chelating nature, which results in positive entropy change (S > 0). They adhere to several isotherms during their adsorption on the metallic surface. The review article discusses the inhibition potential of polypyridyl-based corrosion inhibitors, their adsorption, coordination, chelation and mechanism of corrosion protection. The challenges and opportunities of using polypyridyl-based corrosion inhibitors in coating and aqueous phase applications have also been surveyed. The significance of coordination complexes, regioisomerism, and the relative location of nitrogen atoms have also been discussed.

Environmentally Sustainable Approach of Corrosion Inhibition of Mild Steel in 1 N HCl and 1 N H2SO4 via Antihistamine Loratadine (LT) and Its Amine Derivatives: Computational and Experimental Analysis

The efficacy of pharmaceuticals in mitigating corrosion on metallic substrates has led to the development of a new class of inhibitors that are economically efficient and offer significant environmental benefits. In the present study, for the anticorrosion action of loratadine (LT), 4-(8-chloro-5,6-dihydro-11H-benzo [5,6] cyclohepta[1,2-b] pyridin-11-ylidene)-1-piperidinecarboxylic acid ethyl ester and its amine derivatives (LT1, LT2, and LT3), a theoretical study using DFT was conducted to elucidate the molecular interactions and complex formation mechanisms between these inhibitors and mild steel. The ΔE values for the studied inhibitors-2.17 eV (LT), 3.904 eV (LT1), 3.906 eV (LT2), and 3.85 eV (LT3)-indicate that the LT inhibitor shows greater reactivity compared to the other LT amine derivatives, particularly in terms of electron donation to the metal substrate. After that, the corrosion inhibitory efficacy of parent molecule LT was examined on steel substrate in a medium 1 N hydrochloric and 1 N sulfuric acid and was found to have an efficiency of 98.52 and 80.58%, respectively, (308 K for 100 ppm concentration) deliberated through the electrochemical techniques (PDP and EIS) and gravimetric technique. The reduction in Cdl values from 684.06 to 43.15 μF/cm2 in 1 N HCl and from 693.41 to 83.91 μF/cm2 in 1 N H2SO4 indicates an adsorption process in which inhibitor molecules displace water adsorbed on the metallic substrate, creating a barrier that prevents the metallic substrate from corrosive damage. The surface adsorption aligned with the Langmuir adsorption isotherm with Gibbs-free energy -51 kJ/mol in 1 N HCl and -49.23 kJ/mol in 1 N H2SO4. The AFM analysis with an average roughness of 16.29 nm in HCl and 49.23 nm in H2SO4 validated LT to form a barrier on mild steel, opposing corrosion. The decelerative effect of LT inferred from theoretical and experimental data comply, making them credible corrosion inhibitors.

A sustainable and green method for controlling acidic corrosion on mild steel using leaves of Araucaria heterophylla

There are several studies that announce the inhibitory behavior of this sort of substance to strengthen the shield of metals, which is one of the positive benefits of green inhibitors. In the current investigation, Araucaria heterophylla studied as a green corrosion inhibitor to avert the mild steel during the acidic cleaning. The examination of this plant's ability to control corrosion at different concentrations in the acidic solution used certain expert measures. The electrochemical results suggested that Araucaria heterophylla had a stronger inhibitory effect on mild steel protection from corrosion. After 12 h of immersion, 1000 ppm of A. heterophylla extract produced corrosion inhibition efficacy (about 83.94%). According to the polarization outcomes, the mild steel corrosion current density dramatically decreased with the addition of Araucaria heterophylla extract, going from 1.08 μA/cm2 for the sample without inhibitor to 0.17 μA/cm2 for the sample having 1000 ppm inhibitor and according to electrochemical study the inhibition efficiency was found around 83%. Flavonoids were found in the plant's leaves according to the high-performance thin-layer chromatography profile. The FTIR picks analysis like N-H stretching secondary amine (3337.07 cm-1), CO-O-C-O stretching anhydride (1022.64 cm-1) defined that functional groups and heteroatom were present. By the help of a GC-MS, the suggested inhibitor's components were identified. Scanning electron microscopy suggests that a thin layer or passive film form on the surface. Quantum chemical calculation also supports the experimental results.

Adiantum Capillus-Veneris Extract as a Sustainable Inhibitor to Mitigate Corrosion in Acid Solutions: Experimental, Machine-Learning Simulation, and Multiobjective Optimization

Green corrosion inhibitors have been widely used as sustainable replacements for synthetic organic inhibitors. The application of adiantum capillus-veneris (ACV) extract to mitigate mild steel corrosion in a hydrochloric acid solution was the main focus of this investigation. Corrosion inhibition was studied using electrochemical impedance spectroscopy (EIS) and polarization techniques. EIS curves were modeled using a shallow neural network. Subsequently, a multiobjective genetic algorithm was employed to identify the optimal combination of concentration and time, represented by a Pareto front. EIS revealed an inhibitory efficacy of 88% at the optimal concentration of 800 ppm. Polarization results showed that ACV acted as a mixed inhibitor, and at 800 ppm, the corrosion current density decreased from 105 to 44 μA/cm2. Surface analytical techniques confirmed the corrosion-inhibitory effect of ACV. Results indicated that the sample selected from the lower lobe of the Pareto front, dominated by impedance magnitude, outperformed other tested samples. Furthermore, the machine learning-based corrosion prediction model demonstrated a high accuracy. This work highlighted the viability of machine learning in assessing corrosion resistance and improved the generalization capacity of optimizing corrosion inhibitors.

An eco-friendly corrosion inhibitor for steel used in desalination systems during acid cleaning: Irish ivy extract

Examining Irish ivy extract's (IIE) potential as a novel corrosion inhibitor to preserve C-steel in 2.0 M H2SO4 solution under dynamic conditions is the main goal of this work. Investigations on weight loss, surface morphology, thermodynamics, electrochemistry (polarization and impedance), and adsorption isotherms all contributed to the achievement of this goal. The results demonstrated that the IIE extract's inhibitory effectiveness increases with concentration, reaching a maximum of 94.2% at 0.5 g L-1. The approach that most nearly matched the experiment's results was the Langmuir adsorption isotherm. The activation energy rises to 61.4 kJ mol-1 when IIE extract is added, compared to 46.9 kJ mol-1 (2.0 M H2SO4). The mixed type behavior of the IIE extract was confirmed by electrochemical method. The IIE extract effectively adsorbed on the C-steel, as confirmed by the FT-IR and SEM examinations. Many compounds, including α-hederin, hederacoside C, hederacoside D, and chlorogenic acid, which may operate as the main agents of corrosion control, were found by HPLC analysis of the IIE extract.

Aromaticity of Heterocyclic Compounds and Their Corrosion Inhibition Property: Experimental and Theoretical Analysis

Heterocycle derived moieties, namely, N-(4-methoxyphenyl)-1-(1H-pyrrol-2-yl)methanimine (MPM), 1-(furan-2-yl)-N-(4-methoxyphenyl)methanimine (FMM), and N-(4-methoxyphenyl)-1-(thiophen-2-yl)methanimine (MTM), were synthesized followed by analysis of their structural aspects using FTIR and 1H NMR spectroscopic techniques. The corrosion retarding abilities of the same were distinguished by gravimetric and certain electrochemical measures for mild steel in 0.5 M H2SO4, and MTM was obtained with maximum inhibition efficiency of 97.93% at 250 mg L-1 concentration; the thermodynamic and activation parameters were recorded in this regard. The results were further seen to be supported by various surface studies: SEM-EDS, XPS, AFM, contact angle, and UV-visible spectroscopy. Potentiodynamic polarization studies unveiled the mixed nature of heterocyclic inhibitors with overriding anodic effect. Furthermore, the adsorption of inhibitors over mild steel coupons demarcates the prevalence of physical and chemical interactions in the environment. In addition, the computational studies, global and local reactivity, molecular dynamics, and density functional theory, were employed and the experimental results obtained were found in correlation with the theoretical results.

Electrochemical, gravimetric and surface studies of Phalaris canariensis oil extract as corrosion inhibitor for 316 L type stainless steel in H2O-LiCl mixtures

The corrosion inhibition action of Phalaris canariensis extract on 316 L stainless steel in the H2O-35 (wt%) LiCl mixture at different temperatures has been evaluated with the aid of weight loss, potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy tests. These studies were complemented by Fourier Transformed Infrared spectroscopy, FTIR, gas/mass chromatography analytical techniques and detailed scanning electronic microscopy studies. Results have indicated that Phalaris canariensis extract is an efficient inhibitor, with an efficiency that increases with its concentration, but it decreases as the temperature increases. Phalaris canariensis extract is physically adsorbed onto stainless steel according to a Temkin type of adsorption isotherm. Phalaris canariensis extract affected both anodic and cathodic electrochemical reactions with a stronger effect on the anodic ones, acting, thus, as a mixed type of inhibitor. Main compounds contained in the Phalaris canariensis extract were palmitic and oleic acids, responsible for its inhibitory properties.

Current and emerging trends of inorganic, organic and eco-friendly corrosion inhibitors

Effective corrosion control strategies are highly desired to reduce the fate of corrosion. One widely adopted approach is the use of corrosion inhibitors, which can significantly mitigate the detrimental effects of corrosion. This systematic review provides a thorough analysis of corrosion inhibitors, including both inorganic and organic compounds. It explores the inhibition mechanisms, highlighting the remarkable inhibitive efficiency of organic compounds attributed to the presence of heteroatoms and conjugated π-electron systems. The review presents case studies and investigations of corrosion inhibitors, shedding light on their performance and application potential. Moreover, it compares the efficacy, compatibility, and sustainability of emerging environmentally friendly corrosion inhibitors, including biopolymers from natural resources as promising candidates. The review also highlights the potential of synergistic impacts between mixed corrosion inhibitors, particularly organic/organic systems, as a viable and advantageous choice for applications in challenging processing environments. The evaluation of inhibitors is discussed, encompassing weight loss (WL) analysis, electrochemical analysis, surface analysis, and quantum mechanical calculations. The review also discusses the thermodynamics and isotherms related to corrosion inhibition, further improving the understanding of inhibitor's behavior and mechanisms. This review serves as a valuable resource for researchers, engineers, and practitioners involved in corrosion control, offering insights and future directions for effective and environmentally friendly corrosion inhibition strategies.

Synthesis of new binary trimethoxyphenylfuran pyrimidinones as proficient and sustainable corrosion inhibitors for carbon steel in acidic medium: experimental, surface morphology analysis, and theoretical studies

In this study, synthesis and assessment of the corrosion inhibition of four new binary heterocyclic pyrimidinones on CS in 1.0 M hydrochloric acid solutions at various temperatures (30-50 °C) were investigated. The synthesized molecules were designed and synthesized through Suzuki coupling reaction, the products were identified as 5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1221), 2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1222), 1,3-diethyl-2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1223) and 1,3-dimethyl-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1224). The experiments include weight loss measurements (WL), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). From the measurements, it can be shown that the inhibition efficiency (η) of these organic derivatives increases with increasing the doses of inhibitors. The highest η recorded from EIS technique were 89.3%, 90.0%, 92.9% and 89.7% at a concentration of 11 × 10-6 M and 298 K for HM-1221, HM-1222, HM-1223, and HM-1224, respectively. The adsorption of the considered derivatives fit to the Langmuir adsorption isotherm. Since the ΔGoads values were found to be between - 20.1 and - 26.1 kJ mol-1, the analyzed isotherm plots demonstrated that the adsorption process for these derivatives on CS surface is a mixed-type inhibitors. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM) and Fourier- transform infrared spectroscopy (FTIR) were utilized to study the surface morphology, whereby, quantum chemical analysis can support the mechanism of inhibition. DFT data and experimental findings were found in consistent agreement.

Noncovalent Interactions-Driven Self-Assembly of Polyanionic Additive for Long Anti-Calendar Aging and High-Rate Zinc Metal Batteries

Zinc anodes of zinc metal batteries suffer from unsatisfactory plating/striping reversibility due to interfacial parasitic reactions and poor Zn2+ mass transfer kinetics. Herein, methoxy polyethylene glycol-phosphate (mPEG-P) is introduced as an electrolyte additive to achieve long anti-calendar aging and high-rate capabilities. The polyanionic of mPEG-P self-assembles via noncovalent-interactions on electrode surface to form polyether-based cation channels and in situ organic-inorganic hybrid solid electrolyte interface layer, which ensure rapid Zn2+ mass transfer and suppresses interfacial parasitic reactions, realizing outstanding cycling/calendar aging stability. As a result, the Zn//Zn symmetric cells with mPEG-P present long lifespans over 9000 and 2500 cycles at ultrahigh current densities of 120 and 200 mA cm-2, respectively. Besides, the coulombic efficiency (CE) of the Zn//Cu cell with mPEG-P additive (88.21%) is much higher than that of the cell (36.4%) at the initial cycle after the 15-day calendar aging treatment, presenting excellent anti-static corrosion performance. Furthermore, after 20-day aging, the Zn//MnO2 cell exhibits a superior capacity retention of 89% compared with that of the cell without mPEG-P (28%) after 150 cycles. This study provides a promising avenue for boosting the development of high efficiency and durable metallic zinc based stationary energy storage system.

Corrosion inhibition ability of L-tryptophan and 5-hydroxy-L-tryptophan for mild steel: a combination of experimental and theoretical methods

An investigation into the corrosion inhibition properties of L-tryptophan (TP) and 5-hydroxy-L-tryptophan (5-OH-TP) for mild steel in a 1.0 M HCl acidic medium was conducted using experimental and theoretical methods. Results obtained from polarization curve measurements reveal that TP and 5-OH-TP are effective mixed-type inhibitors, exhibiting the highest inhibition efficiencies of 91.22% and 94.05%, respectively, at a temperature of 293 K and a concentration of 10-2 M. However, their inhibition efficiencies gradually decline with increasing temperature, reaching the lowest values of 70.65% for TP and 73.55% for 5-OH-TP at a concentration of 10-4 M and a temperature of 323 K. The adsorption of TP and 5-OH-TP on the steel surface follows the Langmuir isotherm, suggesting monolayer adsorption. Electrochemical impedance spectroscopy analysis indicates that the adsorbed inhibitors form a protective film, effectively shielding the steel from corrosive agents in the solution. Notably, 5-OH-TP consistently exhibits superior inhibition efficiency compared to TP, attributed to the presence of polar OH groups that facilitate stronger bonding of the inhibitor molecule with the metal surface. Quantum chemical parameters and molecular dynamics simulations further confirm the superior corrosion inhibition ability of 5-OH-TP over TP in acidic environments. In particular, the binding energies of protonated TP at the N3 position and 5-OH-TP at the N4 position are 556.40 and 579.27 kJ mol-1, respectively.

Assessment of the Inhibitory Efficacy of a Thiazole Derivative as an Efficient Corrosion Inhibitor for Augmenting the Resistance of MS in Acidic Environments

Numerous thiazole compounds have been developed as cutting-edge inhibitors because of a rising fascination with using corrosion inhibitors (CIs) and preventative measures to prevent mild steel (MS) from deteriorating. In this study, the ability of a novel thiazole derivative, 2-hydrazono-3-methyl-2,3-dihydrobenzo[d]thiazole hydrochloride (HMDBT), to prevent corrosion of MS (MS) in HCl has been reconnoitered using various approaches, Viz. gravimetric analysis, electrochemical (EC) analysis, and different surface characterizations. With an inhibition efficiency (IE %) of 95.35%, the outcomes elucidate that HMDBT functions as a potent MS CI that is environmentally friendly and sustainable. The computed activation and thermodynamic factors were also employed to better explain the process underpinning the inhibiting tendency of HMDBT. According to the computed values, the HMDBT molecules physically and chemically adhered to the MS surface following the Langmuir model, generating a dense protective layer that may be associated with the presence of a benzene ring and heteroatoms (S & N) in the HMDBT architecture. Based on the findings of the EIS studies, an intensification in the CI's concentration from (50 →800) ppm is ushered by increases in polarization resistance (Rp) from (80.72, 354.31) Ω cm2, and attenuation in double-layer capacitance (Cdl) from (198.78 → 44.13) μF cm-2, respectively, confirming the inhibitory proficiency of HMDBT. The IE of the inhibitor was reported around 95.35% by weight loss measurement and 89.94% through EC measurement. Theoretical analysis including density functional theory (DFT) and molecular dynamics (MD) simulations were carried out to investigate the additional effects of HMDBT on the anticorrosion effectiveness and mechanism of inhibition. The theoretical parameters that were calculated provided important assistance in comprehending the inhibitory mechanism that the CI's moieties disclosed and are in strong concord with experimental methods. To create a "green" inhibitor system, the work presented here provided a potent technique to reduce corrosion by adding a potent new inhibitor.

Unravelling the effects of functional groups on the adsorption of 2-mercaptobenzothiazole on a copper surface: a DFT study

The adsorption of organic compounds onto metal surfaces holds significant importance across various applications, where understanding the intricate interactions between the compounds and the metal surfaces is indispensable. By using density functional theory calculations, this study investigated the impact of functional groups on the interaction between the thione form of 2-mercaptobenzothiazole (MBT) and the Cu(111) surface. The results indicated that substituting functional groups at the C6 position exerts a dual influence on the covalent and non-covalent interactions (NCI). Electron-donating groups enhanced both covalent and non-covalent interactions, whereas electron-withdrawing groups decreased covalent while increasing non-covalent interactions. The covalent interaction between MBTs and Cu(111) is mainly governed by the electron donation from the occupied orbitals of the molecules to the conduction band of copper, with the absolute interaction energies (eV) increasing in the order of MBT-NO2 (0.629) < MBT-COOH (0.660) < MBT-Cl (0.699) < MBT (0.715) < MBT-SH (0.727) < MBT-OH (0.733) < MBT-CH3 (0.735) < MBT-OCH3 (0.749) < MBT-NH2 (0.781) < MBT-NHCH3 (0.792). The influence of functional groups on covalent interactions is clarified by examining changes in the molecule's electronic structure, revealing a linear relationship between covalent interaction energy and HOMO energy, or the Hammett substituent constant. However, the impact of functional groups on non-covalent interactions is more complex and cannot be described by changes in the electronic structure. A novel parameter, the substitution interaction energy, was proposed to capture the effect of functional groups on the NCI-included adsorption energy of MBT derivatives on the Cu(111) surface. The stronger the substitution interaction, the stronger the NCI-included interaction of MBTs on Cu(111). The absolute NCI-included interaction energies follow the order of MBT (2.141) < MBT-Cl (2.213) < MBT-COOH (2.266) < MBT-CH3 (2.294) < MBT-OH (2.331) < MBT-OCH3 (2.379) < MBT-NO2 (2.461) = MBT-NH2 (2.461) < MBT-SH (2.530) < MBT-NHCH3 (2.565). These insights offer valuable guidance for manipulating the adsorption of organic substances on metal surfaces through functional groups in diverse applications.

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.

Unveiling the contemporary progress of graphene-based nanomaterials with a particular focus on the removal of contaminants from water: a comprehensive review

Water scarcity and pollution pose significant challenges to global environmental sustainability and public health. As these concerns intensify, the quest for innovative and efficient water treatment technologies becomes paramount. In recent years, graphene-based nanomaterials have emerged as frontrunners in this pursuit, showcasing exceptional properties that hold immense promise for addressing water contamination issues. Graphene, a single layer of carbon atoms arranged in a hexagonal lattice, exhibits extraordinary mechanical, electrical, and chemical properties. These inherent characteristics have led to a surge of interest in leveraging graphene derivatives, such as graphene oxide (GO), reduced graphene oxide and functionalized graphene, for water treatment applications. The ability of graphene-based nanomaterials to adsorb, catalyze, and photocatalyze contaminants makes them highly versatile in addressing diverse pollutants present in water sources. This review will delve into the synthesis methods employed for graphene-based nanomaterials and explore the structural modifications and functionalization strategies implemented to increase their pollutant removal performance in water treatment. By offering a critical analysis of existing literature and highlighting recent innovations, it will guide future research toward the rational design and optimization of graphene-based nanomaterials for water decontamination. The exploration of interdisciplinary approaches and cutting-edge technologies underscores the evolving landscape of graphene-based water treatment, fostering a path toward sustainable and scalable solutions. Overall, the authors believe that this review will serve as a valuable resource for researchers, engineers, and policymakers working toward sustainable and effective solutions for water purification.

Effect of Adsorption and Interactions of New Triazole-Thione-Schiff Bases on the Corrosion Rate of Carbon Steel in 1 M HCl Solution: Theoretical and Experimental Evaluation

Due to the unique properties of steel, including its hardness, durability, and superconductivity, which make it an essential material in many industries, it lacks corrosion resistance. Herewith, two novel triazole-thione Schiff bases, namely, (E)-5-methyl-4-((thiophen-2-ylmethylene)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione (TMAT) and (E)-4-(((5-(dimethylamino)thiophen-2-yl)methylene)amino)-5-methyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (DMTMAT), were synthesized and characterized. The corrosion inhibition (CI) ability of these two molecules on carbon steel in an aqueous solution of 1 M HCl as well as their interaction with its surface was studied using a number of different techniques. The results confirmed that the CI capability of these organic molecules depends on their strong adsorption on the metal surface and the formation of a protective anticorrosion film. Weight loss tests revealed that the inhibition efficiencies of TMAT and DMTMAT were 91.1 and 94.0%, respectively, at 1 × 10-3 M concentrations. The results of electrochemical impedance spectroscopy (EIS) indicated that there was a direct relationship between the inhibitor concentration and the transfer resistance. Potentiodynamic polarization (PDP) experiments have proven to be mixed-type inhibitors of C-steel in aqueous hydrochloric acid solution and follow the Langmuir adsorption isotherm model. Several thermodynamic and kinetic parameters were calculated. The negative values of the adsorption-free energy are -36.7 and -38.5 kJ/mol for TMAT and DMTMAT, respectively, confirming the spontaneity of the adsorption process. The MD simulation study's findings show that the inhibitor molecules are nearly parallel to the metal surface. The interaction energy calculated by the MD simulation and the inhibitory trend are the same. The practical implementation is consistent with what the computer models predicted.

Electrochemical and computational insights into the utilization of 2, 2- dithio bisbenzothiazole as a sustainable corrosion inhibitor for mild steel in low pH medium

Industries today place a high premium on environmentally friendly supplies that may effectively inhibit metal dissolution at a reasonable cost. Hence, in this paper, we assessed the corrosion inhibition effectiveness of the Thiazole derivative namely, 2, 2-Dithio Bisbenzothiazole (DBBT) against mild steel (MS) corrosion in 1 M HCl. Several experimental approaches, including gravimetric analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and surface exploration using scanning electron/atomic force microscopy (SEM/AFM) and contact angle (CA), were utilized to conduct the measurements. In 1 M HCl corrosive medium at 298 K in the subsistence of 800 ppm of DBBT, this experiment indicated DBBT as an environment-friendly and sustainable corrosion inhibitor (CI) for MS, demonstrating an inhibition efficiency (IE %) of 97.71%. To deliver a deeper knowledge of the mechanism behind inhibitive behavior, the calculated thermodynamic and activation characteristics were applied. The calculated Gibbs free energy values indicated that the CI interacted physically and chemically with the MS surface, validating physio-chemical adsorption. The findings of the EIS research revealed that an upsurge in the doses of the CI is escorted by an upsurge in polarization resistance (Rp) from (88.05 → 504.04) Ωcm2, and a diminution in double layer capacitance (Cdl) from (97.46 → 46.33) μFcm-2 at (50 → 800) ppm respectively, affirming the inhibitive potential of DBBT. Additionally, the greatest displacement in Ecorr value being 76.13 mV < 85 mV, indicating that DBBT act as a mixed-form CI. To study the further impacts of DBBT on the inhibition capabilities of the compound under investigation, density functional theory (DFT) and molecular dynamics (MD) simulation were employed. Chemical and electrochemical approaches are in agreement with the computational analysis indicating DBBT is the most efficient CI.

Progress in the Field of Cyclophosphazenes: Preparation, Properties, and Applications

This review article provides a comprehensive overview of recent advancements in the realm of cyclophosphazenes, encompassing their preparation methodologies, distinctive properties, and diverse applications. The synthesis approaches are explored, highlighting advancements in the preparation of these cyclic compounds. The discussion extends to the distinctive properties exhibited by cyclophosphazenes, including thermal stability characteristics, and other relevant features. Furthermore, we examine the broad spectrum of applications for cyclophosphazenes in various fields, such as coatings, adhesives, composites, extractants, metal complexes, organometallic chemistry, medicine, and inorganic chemistry. This review aims to offer insights into the evolving landscape of cyclophosphazenes and their ever-expanding roles in contemporary scientific and technological arenas. Future possibilities are emphasized, and significant research data shortages are identified.

An overview of contemporary developments and the application of graphene-based materials in anticorrosive coatings

Although graphene and graphene-based materials (GBMs) offer a wide range of possible applications, interest in their use as barrier layers or as reinforcements in coatings for the mitigation of corrosion has grown during the past decade. Because of its unique two-dimensional nanostructure and exceptional physicochemical characteristics, graphene has gotten a lot of attention as an anti-corrosion material. This enthusiasm is largely driven by the requirement to integrate more features, improve anti-corrosion effectiveness, and eventually prolong the service duration of metallic components. As barriers against metal corrosion, graphene nanosheets can be applied singly or in combination to create thin films, layered frameworks, or composites. Concurrently, over the past few years, significant advancements have been made in the establishment of scalable production methods for graphene and materials based on graphene. Since there is currently a wide variety of graphene material with various morphologies and characteristics, it is even more important that the production approach and the intended application be properly matched. This review gathers the most recent data and aims to give the reader a comprehensive overview of the most recent developments in the use of graphene and GBMs in various anti-corrosion strategies. The structure-property correlation and anticorrosion techniques in these systems are given special consideration. The current article offers a critical examination of this topic as well, stressing the areas that require more research.

FG-BERT: a generalized and self-supervised functional group-based molecular representation learning framework for properties prediction

Artificial intelligence-based molecular property prediction plays a key role in molecular design such as bioactive molecules and functional materials. In this study, we propose a self-supervised pretraining deep learning (DL) framework, called functional group bidirectional encoder representations from transformers (FG-BERT), pertained based on ~1.45 million unlabeled drug-like molecules, to learn meaningful representation of molecules from function groups. The pretrained FG-BERT framework can be fine-tuned to predict molecular properties. Compared to state-of-the-art (SOTA) machine learning and DL methods, we demonstrate the high performance of FG-BERT in evaluating molecular properties in tasks involving physical chemistry, biophysics and physiology across 44 benchmark datasets. In addition, FG-BERT utilizes attention mechanisms to focus on FG features that are critical to the target properties, thereby providing excellent interpretability for downstream training tasks. Collectively, FG-BERT does not require any artificially crafted features as input and has excellent interpretability, providing an out-of-the-box framework for developing SOTA models for a variety of molecule (especially for drug) discovery tasks.

Efficiency of Expired Drugs Used as Corrosion Inhibitors: A Review

Corrosion inhibitors represent one of the most commonly used methods for significantly reducing the corrosion rate of metals and alloys. Adsorption inhibitors have a wide range of applications in cooling water systems, deicing solutions for aircrafts, airports and ways, etching and degreasing solutions, oil pipelines, paints and coatings and metal processing solutions. Adsorption corrosion inhibitors of metals and alloys are generally organic compounds that contain structures with heteroatoms (N, P, S, As, O) in their molecules, having lone pair electrons or π electrons in aromatic rings or multiple bonds. They enable relatively strong interactions between the metal atoms and organic molecules, resulting in a protective layer of organic molecules adsorbed at the metal-corrosive solution interface. Most molecules of active substances from drugs contain similar structures, which is why many drugs have been already tested as corrosion inhibitors. One of the major disadvantages of using drugs for this purpose is their particularly high price. To overcome this impediment, the possibility of using expired drugs as corrosion inhibitors has been investigated since 2009. The present paper is an exhaustive compilation of the scientific published papers devoted to the use of expired drugs as corrosion inhibitors in various aggressive solutions. The inhibitory efficiencies of expired drugs are presented as a function of the studied metal or alloy and the nature of the aggressive solution, as well as the concentration of the inhibitor in such a solution. Research has especially been focused on mild and carbon steel and less on stainless steel, as well as on some metals such as copper, zinc, nickel, tin and aluminum and its alloys. The experimental methods used to assess the inhibitory efficiencies of expired drugs are briefly discussed. Also, the available information on the stability of the active substances in the drugs is presented, although most authors were not concerned with this aspect. Finally, several actions are revealed that must be undertaken by researchers so that the results obtained in the study of the anticorrosive action of expired drugs can be applied at the industrial level and not remain only an academic concern.

Recent Developments in 3D Bio-Printing and Its Biomedical Applications

The fast-developing field of 3D bio-printing has been extensively used to improve the usability and performance of scaffolds filled with cells. Over the last few decades, a variety of tissues and organs including skin, blood vessels, and hearts, etc., have all been produced in large quantities via 3D bio-printing. These tissues and organs are not only able to serve as building blocks for the ultimate goal of repair and regeneration, but they can also be utilized as in vitro models for pharmacokinetics, drug screening, and other purposes. To further 3D-printing uses in tissue engineering, research on novel, suitable biomaterials with quick cross-linking capabilities is a prerequisite. A wider variety of acceptable 3D-printed materials are still needed, as well as better printing resolution (particularly at the nanoscale range), speed, and biomaterial compatibility. The aim of this study is to provide expertise in the most prevalent and new biomaterials used in 3D bio-printing as well as an introduction to the associated approaches that are frequently considered by researchers. Furthermore, an effort has been made to convey the most pertinent implementations of 3D bio-printing processes, such as tissue regeneration, etc., by providing the most significant research together with a comprehensive list of material selection guidelines, constraints, and future prospects.

Evaluation of Corrosion Inhibition of Essential Oil-Based Inhibitors on Aluminum Alloys

There is a high demand for eco-friendly, effective, and high-performance corrosion inhibitors for industrial applications. Thus, the corrosion property of aluminum alloys was studied in essential oil-containing sodium chloride solution at various concentrations. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), surface tests, and weight loss analysis were used to study the corrosion inhibition mechanism of the essential oil. The essential oil showed the highest inhibition efficiency of 97.01% at 1000 ppm. A high efficiency of 96.03% was achieved even after 168 h of exposure. The potentiodynamic polarization test showed that the essential oil is a mixed-type inhibitor. EIS results show better adsorption of the oil on the surface of the aluminum at increased inhibitor concentrations. The Langmuir's adsorption isotherm model was found to describe the adsorption behavior. The surface morphology of the uninhibited and inhibited specimens examined by a scanning electron microscope equipped with an energy-dispersive X-ray spectroscope confirmed the protective film of the inhibitor molecules on the aluminum surface.

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.

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

Background

Corrosion is a threat to material strength and durability. Electron-rich organic inhibitor may offer good corrosion mitigation potentials. In this work, anti-corrosion potentials of nine derivatives of 1H-indene-1,3-dione have been investigated using density functional theory (DFT) approach and molecular dynamics (MD) simulation. Chemical reactivity descriptors like energies of lowest unoccupied molecular orbital (ELUMO), highest occupied molecular orbital (EHOMO), electron affinity (A), ionization potential (I), energy gap (ΔEgap), global hardness (η), global softness (σ), electronegativity (χ), electrophilicity (ω), number of transferred electrons (ΔN) and back-donation (ΔEback-donation) were computed at DFT/B3LYP/6-31G(d) theoretical level. The local reactive sites and the charge partitioning on the compounds were studied using Fukui indices and molecular electrostatic potential (MEP) surface analysis. The adsorption behavior and the binding energy of the inhibitors on Fe (110) surface in hydrochloric acid solution were investigated using MD simulation.

Results

The high chemical reactivity, kinetic instability and good corrosion inhibition potentials demonstrated by the inhibitors are rationalized based on their high EHOMO, A, σ, ΔN, ΔEback-donation, and low ΔEgap, ELUMO, I and η. A wide difference of approximately 2.4–3.2 eV between the electronegativities of iron and the 1H-inden-1,3-diones suggests good charge transfer tendency from the latter to the low-lying vacant d-orbitals of iron. The heteroatoms (O and N) and the aromatic moieties are the nucleophilic sites on the inhibitors for effective adsorption on the metal surface as shown by condensed Fukui dual functions and MEP analysis. The MD simulation shows good interaction and strong binding energy between the inhibitor and Fe (110) surface.

Conclusions

Effective surface coverage and displacement of H3O+, Cl− and water molecules from Fe (110) surface by the inhibitors indicate good corrosion inhibition properties of the inden-1,3-diones. 2-((4,7-dimethylnaphthalen-1-yl)methylene)-1H-indene-1,3(2H)-dione display low energy gap, strongest binding interaction and most stabilized iron-inhibitor configuration, hence, the best anti-corrosion potential.

Graphical abstract

Corrosion Inhibition Properties of Phenyl Phthalimide Derivatives against Carbon Steel in the Acidic Medium: DFT, MP2, and Monte Carlo Simulation Studies

The effectiveness of phenyl phthalimide and its derivatives at preventing corrosion of carbon steel has been tested experimentally using gravimetric and electrochemical measurements. However, experimental studies have not thoroughly explained the structural patterns and coating mechanisms of phenyl phthalimide and its derivatives during corrosion inhibition. In this study, the density functional theory (DFT), ab initio MP2, and Monte Carlo simulation are applied to study phenyl phthalimide (PP) and its derivatives as corrosion inhibitors of carbon steel. The geometry, quantum parameters, and reactive site of the inhibitors were determined by DFT and ab initio MP2 methods. The real environment conditions of corrosion inhibition in the solution phase can be replicated by the Monte Carlo simulation. The corrosion inhibition efficiency of phthalimide derivatives is PP-OCH3 > PP-CH3 > PP-H > PP-Cl > PP-NO2. The theoretical study is consistent with previously reported experimental results.

New QSPR model for prediction of corrosion inhibition using conceptual density functional theory

The relationship between structure and corrosion inhibition of a series of twenty-eight quinoline and pyridine derivatives has been established through the investigation of quantum descriptors calculated with PBE/6-311 +  + G** method. A quantitative structure-property relationship (QSPR) model was obtained by examining these descriptors using a genetic algorithm approximation method based on a multiple linear regression analysis. The results indicate that the efficiency of corrosion inhibitors is strongly associated with hardness (η), minimal electrostatic potential (ESP_min), and volume (V) descriptors. Furthermore, the validity of the proposed model is corroborated by an adsorption study on an iron surface Fe(110).