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The present investigation is focussed on unveiling the potential of ecologically safe Chitosan derived N-Acylated products (N-ACs) as anti-corrosive agents for mild steel in 0.5 M H 2 SO 4. Electrochemical Impedance Spectroscopy (EIS) including potentiodynamic polarization (PDP) and potentiostatic electrochemical impedance were deployed to evaluate their anti-corrosive performance and the results of the same reported N-acylated chitosan derivatives project remarkable inhibition efficiency with the most effective performance of 96.80% at 250 mgL-1. The pronounced inhibition efficiency reported was conclusively accredited to the availability of heteroatoms in modified chitosan which further aid in the formation of a protective barrier over mild steel counterparts. The final acylated products were reported to be mixed type as demarcated by PDP results. Further, the prevention ability of modified chitosan was obtained via adsorption and the Langmuir adsorption model was best seen as suitable in this regard. Surface studies and theoretical modeling including Global Reactivity results, molecular Dynamic Modelling (MD), and Density Functional Bond Tight Binding Results (DFBT) were incorporated to gain insights into the molecular level of interactions between metal and N-ACs. [Display omitted] • Use of N-ACs to combat corrosion offers eco-friendly and sustainable option. • Corrosion combating ability of N-ACs is related with their structure. • N-ACs molecules adsorb over metal surface as per Langmuir isotherm. • N-ACs-metal interaction energy decides the corrosion combating ability of BCs molecule. • N-ACs decrease the electrolyte-metal surface contact angle. [ABSTRACT FROM AUTHOR]

The development of cost-effective, sustainable, eco-friendly and efficient compounds is a renovated science and a demanding assignment for today's chemists and technology specialists. In this context, the anticorrosion effect of a new Schiff base hydrazone, namely (E)-2-(4-(2-(methyl(pyridin-2-yl)amino)ethoxy)benzylidiene)hydrazine-1-carboxamide (MPAH) against the mild steel (MS) surface in 1.0 M HCl has been analyzed utilizing experimental methods, thermodynamic characterizations, and computational studies. MPAH has proven to be an effective inhibitor in 1.0 M HCl solution. Its inhibition performance improved by raising the concentration of the compound to an optimal concentration of 5 × 10−3 M, and 97% efficiency was achieved at 303 K. Inhibitor adsorption on the MS has been explicated with both physical and chemical interactions. The adsorption was in accordance with the isotherm of Langmuir. The impact of MPAH on the surface of MS had been confirmed utilizing SEM/EDX, electrochemical impedance spectroscopy (EIS), gravimetric measurements (WL), and potentiodynamic polarization (PDP). The adsorption of the studied compound on the MS surface has also been investigated by DFT and the molecular dynamics (MD) simulations. [ABSTRACT FROM AUTHOR]

The chemical composition of the methanolic extract of Ammi visnaga (Khella) seeds from the Sidi Slimane region is determined for the first time by Gas Chromatography coupled with Mass Spectrometry (GC/MS). Ten compounds representing 99.638% of the total extract were identified. Khellin (49.011%), Visnagin (26.537%) and Dimethylethylamine (15.108%) are the major components. Moreover, the inhibitory effect of the Methanolic extract of the seeds of Ammi visnaga on the corrosion of mild steel in a solution of 1M HCl is determined using weight loss measurements, the potentiodynamic technique as well as the technique of electrochemical impedance spectroscopy (EIS). It is found that the extract reduces the corrosion rate of the steel in the acid solution. Inhibition efficiency increases as the concentration of the extract increases. The tested compound has an inhibition efficiency of 84% for a concentration equal to 1.0 g/L. The polarization measurements indicate that the examined extract acts as a mixed inhibitor with predominant anodic efficacy. The data obtained from EIS studies are analyzed to model this process using appropriate equivalent circuit models. The adsorption of the extract on the surface of the mild steel obeys the Langmuir adsorption isotherm in acidic medium and the activation is determined and discussed. [ABSTRACT FROM AUTHOR]

Poor corrosion resistance of mild steel (MS) is a serious concern in many industrial applications. Application of corrosion inhibitors is a possible solution to combat steel corrosion. As yet, there is very little research reported focusing on hydrazone derivatives as corrosion inhibitors, here we present a combined experimental and theoretical study of the adsorption of three newly synthesized hydrazones (HDZs), namely, (E)-N′-(4-(dimethylamino)benzylidene)-2-((2,3-dimethylphenyl)amino)benzohydrazide (HDZ-1), (E)-2-((2,3-dimethylphenyl)amino)-N′-(4-methylbenzylidene)benzohydrazide, (HDZ-2) and (E)-N′-benzylidene-2-((2,3-dimethylphenyl)amino)benzohydrazide (HDZ-3) on the MS surface in 1 M HCl. The interaction of HDZs and the metal surface was investigated using electrochemical techniques, X-ray photoelectron spectroscopy (XPS), DFT and molecular dynamic (MD) simulations. XPS shows that inhibitor molecules form a stable layer on steel surface through chemical and physical interactions. HDZs adsorption onto the steel surface was found to follow Langmuir model. Furthermore, electrochemical measurement results demonstrated that our developed inhibitors act as of mixed-type (anodic and cathodic), with HDZ-1 showing the highest polarization resistance and lowest corrosion current density. Scanning electron microscope (SEM) was used to examine the surface morphology of the steel samples. The new hydrazones showed significantly improved steel corrosion resistance, which provides opportunities to explore the inhibitive activity of structurally similar compounds. [ABSTRACT FROM AUTHOR]

A novel quinazoline derivative, 3-cyclopropyl-3,4-dihydroquinoline-2(1H)-One (CPHQ), was successfully designed and synthesized. Then, its corrosion inhibition behavior on carbon steel (CS) surface in 1.0 M HCl at different temperatures was investigated using chemical, electrochemical and theoretical techniques. The experiments confirmed that the studied inhibitor shows inhibition efficiency as high as 95% even at very low concentration of 5 × 10−3 M. To ascertain the nature of adsorption of CPHQ molecules on CS surface, Langmuir adsorption isotherm model was best fitted. From potentiodynamic polarization (PDP) calculations, it was concluded that the CPHQ acted as a mixed type corrosion inhibitor. Electrochemical impedance spectroscopy (EIS) studies revealed that increase in CPHQ concentration, resulted in an increase in the polarization resistance with a simultaneous decrease in the double-layer capacitance values. PDP tests were also performed to understand the corrosion behavior of CS as a function of temperature without and with varying concentrations of CPHQ, at temperatures 303, 313, 323, and 333 K. It can be concluded that the corrosion inhibition effect was dependent on the concentration of the inhibitor and the solution temperature. In order to understand the basic insights of the action mode of CPHQ molecules, Density Functional Theory (DFT) method, and Molecular Dynamic (MD) simulations were also employed on the optimized structure of CPHQ. [ABSTRACT FROM AUTHOR]

The corrosion inhibition performance of three triazine derivatives namely 4-((2-(5,6-diphenyl-1,2,4-triazin-3-yl)hydrazineylidene)methyl)-N,N-dimethylaniline (HT-1), 3-(2-(4 methoxybenzylidene) hydrazineyl)-5,6-diphenyl-1,2,4-triazine (HT-2) and 2-(2-(5,6-diphenyl-1,2,4-triazin-3-yl)hydrazineylidene)methyl)phenol (HT-3)on mild steel corrosion in1MHCl has been studied using gravimetric method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), Density functional theory (DFT) and molecular dynamics simulation. The corrosion inhibition efficiencies at optimum concentration (80 mg L -1 ) are 98.6% (HT-1), 97.1%(HT-2) and 94.3% (HT-3) respectively at 308 K. The corrosion inhibition efficiency increases with increase in concentration and decreases with increase in temperature. The adsorption of HTs on the surface of mild steel obeyed Langmuir isotherm. Potentiodynamic polarization study confirmed that inhibitors are mixed type with cathodic predominance. SEM analysis confirmed that metal surface is smooth in presence of inhibitors. Quantum chemical calculation and Molecular dynamics simulation further support the experimental findings. [ABSTRACT FROM AUTHOR]

The corrosion inhibition properties of three quinoline derivatives namely, 2,6-dichloroquinoline-3-carbaldehyde (QA-1), 2-chloro-6-nitroquinoline-3-carbaldehyde (QA-2) and 2,6-dichloro-8-nitroquinoline-3-carbaldehyde (QA-3) for mild steel (MS) in 1.0 M HCl at 303 K were studied by using electrochemical techniques, the density functional theory and molecular dynamic simulations. Experimentally obtained results showed that the quinoline derivatives are excellent inhibitors and that their adsorption on metal surface was found to follow that of the Langmuir adsorption model. Electrochemical findings revealed that quinoline derivatives behave as mixed-type inhibitors. These inhibitors increased the polarization resistance and simultaneously lowered the double layer capacitance, thereby confirming their high potentialities to protect metal against dissolution. Surface morphology of the MS surface in both the absence and presence of quinoline derivatives was examined using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The mechanism of inhibition action of the studied quinolines was discussed in the light of the DFT and molecular dynamic (MD) simulations studies. New insights were brought by a diffusion model and radial distribution function (RDF). Theoretical results agree well with the experimental results. [ABSTRACT FROM AUTHOR]

In this work, an eco-friendly antipsychotic, namely clozapine (CZP) was used to investigate the mild steel (MS) corrosion inhibition process in 1 M HCl, using weight loss (WL) measurements, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS). The performance of the CZP on the corrosion inhibition of MS was also evidenced by scanning electron microscopy (SEM). Results show that the CZP is a good inhibitor and inhibition efficiency ( IE %) reach 96% at an optimum concentration of 10 − 3 M. Potentiodynamic polarization curves showed that the CZP affects both cathodic and anodic current and may be classified as mixed type inhibitor in HCl medium. In addition, the IE % increased with a rise in CZP concentration. While the adsorption of tested compound on MS surface was found to follow the Langmuir isotherm. Furthermore, the molecular dynamic (MD) simulations, radial distribution function (RDF) and quantum chemical parameters have been calculated and discussed in view of the results earlier reported. [ABSTRACT FROM AUTHOR]

In this work, the effect of potassium ferrocyanide ( Pf) on the corrosion of mild steel in solutions of phosphoric acid (HPO) has been investigated in relation to the concentration of the inhibitor by weight loss, potentiodynamic polarization and AC impedance (EIS) measurements. The results obtained revealed that this compound is good a mixed-type inhibitor. The effect of temperature on the corrosion behavior with the addition of optimal concentration of Pf was studied in the temperature range 298-328 K. The value of inhibition efficiency decreases slightly with the increase in temperature. Changes in impedance parameters (charge transfer resistance, R, and double layer capacitance, C) were indicative of adsorption of Pf on the metal surface, leading to the formation of a protective film. Adsorption of Pf on the C38 steel surface was found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined. [ABSTRACT FROM AUTHOR]

The inhibitive action of verbena essential oil (VEO) on the corrosion of mild Steel in 1 M HCl solutions in the temperature range 298 to 328 K was measured by use of the weight-loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy. Results showed that VEO inhibited corrosion of C38 steel in 1 M HCl solution and that inhibition efficiency increased with increasing concentration of inhibitor but decreased proportionally with temperature. Potentiodynamic polarization studies suggested VEO is a mixed-type inhibitor, with the anodic type predominating. Nyquist plots were depressed semicircles with their centre below the real axis. Adsorption of VEO by the C38 steel surface followed the Langmuir adsorption isotherm. Kinetic data for dissolution were investigated. [ABSTRACT FROM AUTHOR]

Argan hulls extract (AHE) was tested as corrosion inhibitor for mild steel in 1 M HCl. Weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) revealed that inhibiting action increased with increasing concentration of the inhibitor. The highest efficiency 97.3% was obtained at 5 g/L AHE. There was good agreement between gravimetric and electrochemical methods (potentiodynamic polarization and EIS). Results obtained from EIS measurements were analyzed to model the corrosion-inhibition process by use of the appropriate equivalent circuit model; a constant phase element was used. Polarization measurements show also that AHE acts as good mixed inhibitor. AHE is adsorbed on the steel surface in accordance with a Langmuir isotherm adsorption model. [ABSTRACT FROM AUTHOR]

There has been substantial research undertaken on the role of green synthesized corrosion inhibitors as a substantial approach to inhibit the corrosion of metals and their alloys in acidic environments. Herein, electrochemical studies, surface characterization, and theoretical modeling were adopted to investigate the corrosion inhibition proprieties of novel synthesized quinoxaline derivatives bearing 8-Hydroxyquinoline, namely 1-((8-hydroxyquinolin-5-yl) methyl)-3,6-dimethylquinoxalin-2(1H)-one (Q1) and 1-((8-hydroxyquinolin-5-yl)methyl) quinoxalin-2(1H)-one (Q2) on mild steel corrosion in 1 mol/L HCl solution. The principal finding of this research was that both inhibitors acted as good corrosion inhibitors with Q1 having the highest performance (96% at 5 × 10−3 mol/L). Electrochemical results obtained via potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques demonstrated that quinoxaline compounds belonged to mixed-type inhibitors; their presence significantly increased the polarization resistance, preventing simultaneously anodic and cathodic reactions. Further, experimental results provided preliminary insights about the interactions mode between studied molecules and the mild steel surface, which followed the Langmuir adsorption model, and physical and chemical interactions assisted their inhibition mechanism. Besides, SEM analyses confirmed the existence of protective film on the metal surface after the addition of 5 × 10−3 mol/L of quinoxalines. In addition, the temperature and immersion time effects on inhibition performances of quinoxalines were investigated to evaluate their performances in different operating conditions. Besides, Density Functional Theory (DFT) and molecular dynamics (MD) simulations were carried out to explore the most reactive sites of quinoxaline inhibitors and their interaction mechanism. Theoretical results revealed that the inhibitor molecule with additional electron-donating functional group strongly interacted with the steel surface. [ABSTRACT FROM AUTHOR]

The corrosion-inhibiting performance of (E)-N'-(4-bromobenzylidene)-2-(6-methoxynaphthalen-2-yl) propanehydrazide (BPH) and (E)-N'-(4-(dimethylamino) benzylidene)-2-(6-methoxynaphthalen-2-yl) propanehydrazide (MPH) for mild steel (MS) in 1.0 M HCl was investigated using electrochemical methods, weight loss measurements, and scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscope (EDX) analysis. Raising the concentration of both inhibitors towards an optimal value of 5 × 10−3 M reduced the corrosion current density (icorr) and the corrosion rate of mild steel. The inhibitory effect of MPH, which showed the highest inhibition efficiency, was explored under a range of temperatures between 303 and 333 K. The inhibitory performance of both compounds significantly improved when the inhibitor concentration increased. The main result that flowed from potentiodynamic polarization (PDP) tests was that both compounds acted as mixed-type inhibitors, with a predominance cathodic effect. The adsorption of both compounds follows the Langmuir isotherm. SEM/EDX confirmed the excellent inhibition performance of tested compounds. [ABSTRACT FROM AUTHOR]

Understanding and predicting adsorption capacities of corrosion inhibitors on the metal surface is of great significance for designing high-performance inhibitor molecules. Herein, a computational methodology, which utilizes molecular dynamics (MD) simulation and Density Functional Theory (DFT), was adopted to investigate the inhibition performance of four hydrazone derivatives (HDZ1-HDZ4) on mild steel corrosion in acidic medium. The adsorption of the four compounds on the Fe (110) surface was studied and analyzed using global and local reactivity descriptors, molecular electrostatic potential (MEP), MD, and radial distribution function (RDF). MD results showed that the binding energy of investigated compounds with the iron surface follows the order of HDZ1 (912 kJ/mol) > HDZ2 (857 kJ/mol) > HDZ3 (801 kJ/mol) > HDZ4 (711 kJ/mol). Furthermore, the fractional free volume (FFV) and the interaction energy were selected for the evaluation of the diffusion behavior of hydronium and chloride ions inside inhibitor films. The results showed that both factors had a vital effect on the diffusion coefficient of corrosive particles. All results proved that inhibitor molecules having a high electron-accepting ability interact actively with the iron surface. Additionally, a direct relationship was observed between the experimentally determined inhibition efficiency and the adsorption strengths obtained from DFT and MD studies. Unlabelled Image • Hydrazone-based corrosion inhibitors were studied using molecular dynamics and DFT. • The electron-accepting ability of compounds affects their adsorption properties. • The Inhibitors' film behavior was studied by mean square displacement and free volume. • There is a good correlation between theoretical and experimental results. [ABSTRACT FROM AUTHOR]

This research aimed to develop a better understanding of the corrosion inhibition of the mild steel in acidic medium by new organic molecules. For this purpose, two new compounds namely, 2,3-dihydrobenzo[4,5]imidazo[2,1-b]thiazole (2-BIT) and 3,4-dihydro-2H-benzo[4,5]imidazo[2,1-b]thiazole (3-BIT) were synthesized and evaluated for mild steel (MS) corrosion in HCl. Analyses were carried out using weight loss measurements, electrochemical techniques, and scanning electron microscope (SEM). The adsorption of inhibitors onto the steel surface follows the Langmuir adsorption model. Generally, results showed that the corrosion inhibition efficiency of the investigated molecules was found to increase with increased concentration of inhibitors. Electrochemical tests, i.e., electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques, showed that the addition of our investigated inhibitors decreases the dissolution of the metal and generally act as mixed-type inhibitors. In addition, the influence of temperature (from 303 to 333 K) on the corrosion inhibition was studied, and the results demonstrated that with an increase in temperature, the inhibition efficiency decrease. SEM results confirmed that the inhibition process is due to a protective film that prevents corrosion. Similarly, the results showed that the inhibitory efficiencies reach 93% at 5 × 10−3 M in the case of inhibitor 3-BIT. These results revealed that this compound could effectively control and reduce the corrosion rate of mild steel in the corrosion test solution. [ABSTRACT FROM AUTHOR]

Various experimental and theoretical methods have been employed to study the effectiveness of two pyrazoline derivatives namely, 2-(4-(5-(p-tolyl)-4,5-dihydro-1H-pyrazol-3-yl)phenoxy)acetic acid (P1) and 2-(4-(5-(4-nitrophenyl)-4,5-dihydro-1H-pyrazol-3-yl)phenoxy)acetic acid (P2) as corrosion inhibitors for mild steel in 1.0 M HCl at 303 K. The inhibitors show high inhibition efficiency and their adsorption on mild steel surface was found to obey Langmuir adsorption isotherm. Potentiodynamic polarization results revealed that both compounds behaved as mixed-type inhibitors. The results from electrochemical impedance spectroscopy studies reveal an increase in polarization resistance. Density Functional Theory calculations and molecular dynamic simulations were used to give basic insights into the action mode of inhibitors as well as to substantiate the experimental results. The surface morphology of the mild steel surface was examined using Scanning Electron Microscopy and Atomic Force Microscopy. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The study shows that FG is an excellent corrosion inhibitor for mild steel in HCl. • Potentiodynamic polarization curves reveal that tested inhibitor acts as a mixed type. • The adsorption of the compound obeys Langmuir adsorption isotherm. • Surface morphology was examined by XPS and SEM. • DFT and MD stimulation studies have been done. Abstract Nowadays, a properly designed corrosion protection system, which is essential for large-scale practical application remains a big challenge. Herein, we report a combined experimental and theoretical study of the adsorption of a galactomannan polysaccharide, namely, Fenugreek gum (FG) on the mild steel (MS) surface in 1.0 M HCl by using electrochemical techniques, X-ray photoelectron spectroscopy (XPS), DFT, molecular dynamic (MD) simulations, radial distribution function (RDF) and mean square displacement (MSD). XPS results show that the FG forms a layer on steel surface. FG adsorption onto the steel surface was found to follow Langmuir model. The electrochemical results demonstrated that FG acts as mixed-type inhibitor. Scanning electron microscope (SEM) was used to examine the surface morphology of the samples. Our findings provide deeper insights into understanding the interaction mechanisms of FG with MS and can be helpful to explore novel approaches to mitigate the steel dissolution occurring at the acidic environment. [ABSTRACT FROM AUTHOR]

The effect of three chalcone derivatives namely, (E)-ethyl 2-(4-(3-(4-fluorophenyl)acryloyl)phenoxy)acetate (AE-1), (E)-ethyl 2-(4-(3-(3,4-dichlorophenyl)acryloyl)phenoxy)acetate (AE-2) and (E)-ethyl 2-(4-(3-(2,5-dimethoxyphenyl)acryloyl)phenoxy)acetate (AE-3) on the mild steel (MS) corrosion in 1.0 M HCl at 303 K has been investigated using experimental techniques such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) methods, weight loss measurements and computational studies. The chalcones derivatives show high inhibition activities and their adsorption on mild steel surface was found to follow the Langmuir adsorption model. PDP results revealed that chalcone derivatives act as a mixed type inhibitors. The results from EIS analysis reveal an increase in charge transfer resistance confirming the inhibitive ability of tested inhibitors. The electronic properties derived from, DFT calculations, molecular dynamic (MD) simulations and Radial Distribution Function (RDF) were used to give further insights into the action mode of studied chalcones. Theoretical results correlate well with the experimental efficiency. Surface morphology of the MS surface in absence and presence of chalcone derivatives was examined using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). [ABSTRACT FROM AUTHOR]

To date, the corrosion of metal surfaces is one of challenging problems in the modern business (technology and industrial applications). So, corrosion control of metal at different stage of application is necessary. To avoid this problem, organic and inorganic corrosion inhibitors are widely used. For this purpose, the present study deals with the corrosion inhibition assessment of novel uridine- (Murmu et al., 2020; Dehghani et al., 2020; Li et al., 2020) [1,2,3]triazole nucleosides as green corrosion inhibitors, namely 2-(acetoxymethyl)-6-(4-((3-(3,4-diacetoxy-5-(acetoxymethyl)tetrahydrofuran-2-yl)-2,6-dioxo-3,6-dihydropyrimidin-1(2H)-yl)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate (TPTAc) and 2-(acetoxymethyl)-5-(3-((1-(3,4-diacetoxy-5-(acetoxymethyl)tetrahydrofuran-2-yl)-1H-1,2,3-triazol-4-yl)methyl)-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)tetrahydrofuran-3,4-diyl diacetate (TPDAc). After synthesis and characterization procedure, the corrosion inhibition performances of these compounds against the corrosion of mild steel (MS) are studied using both experimental and theoretical exploration. The effect and inhibition action of these inhibitors on the electrochemical behavior of MS corrosion was evaluated experimentally via electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss techniques. In addition, theoretical calculations are made to analyze adsorption properties and characteristics of synthesized molecules on MS surface. The results obtained from all electrochemical experiments confirmed that the inhibitors understudy exhibited high inhibition performances thanks to their adsorption capacity on MS surface. EIS data indicated that TPTAc is quite effective at 5 × 10−3 M than TPDAc at the same concentration. PDP results revealed that the studied molecules acted as mixed-type inhibitors and they had a strong influence on the protective layer formed. The corrosion rate (CR) values considerably fall down from 1.135 mg cm−2 h−1 to 0.090 and 0.158 mg cm−2 h−1 at 5 × 10−3 M of TPTAC and TPDAc, respectively. Moreover, the effect of KI ions was also evaluated, and the results suggest that the presence of iodide ions has significantly improved the inhibition performances (97% for TPTAc and 90% for TPDAc at 5 × 10−3 M). Also, the calculated values of Gibb's free energy (Δ G ads 0) are −33.61 kJ/mol and −34.33 kJ/mol for TPTAC and TPDAc, respectively; lying between −21 and −40 kJ/mol, confirming both physisorption as well as chemisorption interactions. In addition, results indicated that the inhibition intensity of studied compounds was expected to happen by means of adsorption over the MS surface which obeys the Langmuir's adsorption isotherm. The surface characterizations confirmed previous findings and contributed additional evidence on the morphological changes of MS surface during corrosion. The anti-corrosive and adsorption properties of studied compounds were detailed by DFT and molecular dynamics (MD) simulations. The results of theoretical calculations demonstrate strong and consistent agreement with experimental outcomes. [Display omitted] • The tested uridine- [1–3]triazole nucleosides have a good inhibition performance. • TPTAc provides greater inhibition efficiency than TPDAc as proven by both theoretical and experiments. • The addition of iodide ions has significantly improved the inhibition efficiency. • Adsorption of TPTAc and TPDAc compounds followed Langmuir isotherm model. • We correlate theoretical observations with experimental results. [ABSTRACT FROM AUTHOR]

Abstract Corrosion protective performance of commercial mild steel (soft steel) by urispas drug was evaluated by gravimetric measurements, potentiostatic polarization and electrochemical impedance spectroscopy in 1 M H 2 SO 4 solution. The results indicate that urispas acts as quite a good corrosion constraint for mild steel exhibiting 97.85% inhibition efficiency at 150 ppm of the drug at 303 K on polarizing it electrochemically which is a quite minified amount of urispas. Weight loss study also shows that inhibition efficiency gets optimized at 150 ppm of the drug molecule at lower temperature. Polarization curves depict that the drug acts as a mixed type inhibitor. The results of electrochemical impedance spectroscopy (EIS) indicate that the charge transfer phenomenon controlled the corrosion reaction. The morphological behavior of the uncorroded and corroded coupons was investigated by scanning electron microscopy and atomic force microscopy studies. The mechanism of adsorption from the variation of inhibition effectiveness with kinetic and activation parameter through Langmuir, Freundlich, Frumkin and Flory-Huggins isotherm, put forward a significant physiochemical mode of interaction of the drug on the metal surface. The outcomes obtained from all the experimental techniques and the information obtained via molecular dynamics (MD) and density functional theory (DFT) evaluation are in good correlation. Highlights • Corrosion inhibition of urispas drug was appreciable. • At 150 ppm of the drug dose, the efficiency got optimized. • Weight loss, electrochemical, MD and DFT data correlate satisfactorily. • All the studied adsorption isotherms correspond well with other findings. [ABSTRACT FROM AUTHOR]

Gum Acacia (GA) was evaluated for steel inhibition in acidic medium. Weight loss, EIS, and by polarization potentiodynamic curves were used to test it. GA showed a high efficiency in protecting steel from acid, and found as dependent on its concentration (1.0 g/L). AFM allowed comparing the morphology of steel with GA, which was complemented with XPS spectroscopy, which confirmed the complete adsorption of GA by evaluating the surface film composition. Polarization resistance increases when GA concentration does, based on EIS characterization, indicating the formation of a protective layer whereas PDP results showed that, GA behaves as a mixed-type inhibitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel 1,2,3-triazolyl nucleosides are used for corrosion of mild steel in HCl. • The addition of KI to HCl significantly improved the performance of nucleosides. • XPS analysis confirms the adsorption of molecules and iodide ions on mild steel. • DFT, MD and RDF analyses support the adsorption of molecules on iron surface. The search for new effective and eco-friendly corrosion inhibitors seems to be a never-ending task for practical applications. Herein, the principal objective of this work is to investigate the corrosion inhibition effect of novel 1,2,3-triazolyl nucleosides namely, 2-(acetoxymethyl)-5-(3-((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)tetrahydrofuran-3,4-diyl diacetate (TBAc) and 2-(acetoxymethyl)-5-(3-((1-(naphthalen-2-ylmethyl)-1H-1,2,3-triazol-4-yl)methyl)-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)tetrahydrofuran-3,4-diyl diacetate (TNAc) for mild steel (MS) in HCl solution. Different amounts of TBAc and TNAc inhibitors were prepared in 1.0 mol/L HCl medium, and their inhibition effect was investigated via electrochemical measurements, X-ray photoelectron spectroscopy (XPS), quantum chemical calculations (DFT), and molecular dynamics (MD) modeling. Further, we have examined the effect of iodide ions on inhibition efficiency, and the obtained data were compared and discussed. Results showed that these green compounds exhibited high inhibition performances thanks to their excellent molecular and electronic properties. They indicated that TNAc and TBAc showed high corrosion inhibition efficiencies at 5x10-3 mol/L with 0.1 mmol/L of KI. The inhibition efficiency of TNAc and TBAc reached 85% and 79% at 5x10-3 mol/L, while it improved to 94% and 91% in the presence of KI, respectively. Electrochemical tests revealed that the studied molecules acted as mixed-type inhibitors and they had a significant effect on the polarization resistance of mild steel. Moreover, the surface morphology analysis was performed using a scanning electron microscope (SEM) and XPS. Besides, a systematic understanding of how these molecules are adsorbed on steel surface was theoretically investigated. Taken together, experimental and theoretical results suggested a significant role of molecular properties of studied derivatives along with intermediate species in promoting their adsorption behavior. A consistent association was found between electrochemical measurements and theoretical calculations. [ABSTRACT FROM AUTHOR]

• The studied inhibitors were synthesized from Naproxen-based hydrazones. • They have a good inhibition effect for the corrosion of mild steel in 1 M HCl solution. • Results from electrochemical and weight loss measurements are quite comparable. • Adsorption of hydrazone derivatives followed Langmuir isotherm model. • All the experimental results showed good agreement with DFT and MD studies and explained adsorption mechanism. Increasing scientific focus has recently been placed on inhibiting the corrosion of metals and their alloys in acidic environments. In doing so, an understanding and explanation of the adsorption of two environmentally friendly corrosion inhibitors, namely (E)-2-(6-methoxynaphthalen-2-yl)-N'-(1-phenylethylidene)propanehydrazide (PHD-H) and (E)-N'-(1-(4-bromophenyl)ethylidene)-2-(6-methoxynaphthalen-2-yl)propanehydrazide (PHD-Br) on a mild steel (MS) surface in 1.0 M HCl solution and their inhibition efficiency was sought in this study. To this end, both electrochemical and theoretical approaches were used to evaluate the anticorrosive effect of two studied compounds. Based on the obtained results, it was apparent that both inhibitors showed excellent protective efficacy, with PHD-Br compound showing the best inhibition performance reaching 95 % at 5 × 10−3 M. Experimental results obtained by electrochemical techniques indicated that the presence of PHD-H and PHD-Br compounds significantly increased the polarization resistance and affected anodic and cathodic reactions, i.e., mixed type inhibitors. Besides, their adsorption followed the Langmuir isotherm model. The stability of the PHD-Br at higher temperatures (303 K–333 K) was investigated by weight loss measurements. To explain this observed efficiency-temperature relationship, the same extreme temperature conditions have been studied theoretically by molecular dynamics (MD) simulations. In addition, the study revealed that a protective barrier was formed by adsorption of the investigated compounds on the surface of the MS, which is confirmed by scanning electron microscopy with energy-dispersive x-ray analysis (SEM-EDX) analysis. Beyond this, Density Functional Theory (DFT), MD simulation and radial distribution function studies have been carried out. Their theoretical results, which are in good agreement with the experimental ones, have shown that corrosion inhibition performance is a result of strong donor-acceptor interactions between the inhibiting compounds and the metal surface. This study provides an approach based on electrochemical and theoretical techniques to control the mild steel loss by using new naproxen-based hydrazones that are anticipated to inhibit the corrosion of steel in an acidic medium. [ABSTRACT FROM AUTHOR]

The current investigation seeks to explore the adsorption mechanism of newly synthesized Naproxen-based hydrazones on mild steel (MS) surface in 1.0 M HCl solution and their corrosion inhibition efficiencies. To this end, two hydrazone derivatives namely, (E)-N′-(1-(4-chlorophenyl)ethylidene)-2-(6-methoxynaphthalen-2-yl)propanehydrazide (PHD Cl) and (E)-N′-(1-(4-hydroxyphenyl)ethylidene)-2-(6-methoxynaphthalen-2-yl)propanehydrazide (PHD-OH) were synthesized, characterized and their corrosion inhibition effects were evaluated using a combined electrochemical and theoretical approach. It is evidently clear from the findings presented in this investigation that the two inhibitors exhibited excellent protection efficiency, and the best inhibition performance was shown by PHD-OH inhibitor (96% at 5 × 10−3 M). Weight loss measurements revealed that the optimum concentration of inhibitors is 5 × 10−3 mol/L. The experimental results obtained by electrochemical techniques (potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)) indicated that the presence of PHD-Cl and PHD-OH compounds greatly increased the polarization resistance and affected both anodic and cathodic reactions, i.e. mixed-type inhibitors. Based on electrochemical results, the polarization resistance was greatly increased, from an initial value for the MS (in 1.0 mol/L HCl) of 29 up to 871 Ω cm2 for the inhibited solution (1.0 mol/L HCl with 5 × 10−3 mol/L of PHD-OH). Furthermore, the adsorption isotherm coincides well with the Langmuir isotherm model. The effect of temperature on PHD-OH adsorption was investigated, experimentally using weight loss tests, and theoretically using molecular dynamic simulations (MD). Moreover, the study found that a protective barrier was set up through the adsorption of the studied compounds on MS surface which is confirmed by scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX).Moreover, molecular proprieties of corrosion inhibitor molecules were explored from a theoretical viewpoint using Density Functional Theory (DFT), molecular dynamic (MD) simulation and radial distribution function (RDF) studies. Theoretical results that were in good agreement with experimental findings demonstrated strong interactions between inhibitor molecules and metal surface. Unlabelled Image • Two hydrazones have a good corrosion inhibition effect for mild steel in HCl. • Results from electrochemical and weight loss measurements are quite comparable. • Surface morphology of mild steel was examined by SEM and EDX. • The adsorption of hydrazones on mild steel surface followed Langmuir isotherm model. • Theoretical results were in accordance with experimental results. [ABSTRACT FROM AUTHOR]

This study set out to examine the corrosion inhibiting properties of two novel benzimidazole derivatives, namely 1,4-bis(2-(4-chlorophenyl)-1H-benzo d imidazol-1-yl)butane (IM-Cl) and 1,4-bis(2-phenyl-1H-benzo d imidazol-1-yl)butane (IM-H) towards mild steel in HCl solution. In this study, gravimetric, electrochemical and scanning electron microscopy (SEM) techniques were applied to gain a detailed understanding of inhibition effects of IM-Cl and IM-H on steel corrosion. Also, the present study aimed to explore the relationship between functional properties of the inhibitor molecules and their adsorption capacities on the MS surface with the aid of computational methods. Experimental results obtained by weight loss, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements revealed that tested compounds had a good anticorrosion capacity. Chloride substituted benzimidazole demonstrated the best inhibition performance reaching 93% at 5 × 10−3 mol/L. The polarization technique (PDP) showed that the target molecules belonged to mixed-type inhibitors, preventing simultaneously anodic and cathodic reactions. Besides, the interactions mode between benzimidazole derivatives and mild steel surface followed the Langmuir adsorption model, and physical and chemical interactions assisted the adsorption mechanism of both compounds. EIS measurements illustrated that the imidazole derivatives made a positive impact on the mild steel corrosion process by increasing the polarization resistance with an increase in the concentration of the inhibitors. SEM analyses were performed to examine the surface morphology of uninhibited and inhibited steel and demonstrated good protection of the mild steel surface in the presence of tested compounds. Further, the temperature and immersion time effects on inhibition performances of benzimidazole were examined to evaluate the stability of these compounds under different operating conditions. Additionally, information extracted from theoretical approaches using Density Functional Theory (DFT) and molecular dynamics (MD) studies is in agreement with those obtained by experimental methods, which corroborate the strong anticorrosion activity of benzimidazole compounds under investigation. Unlabelled Image • Benzimidazole derivatives have a good inhibition effect for the corrosion of mild steel in 1 M HCl solution. • Results from electrochemical and weight loss measurements are quite comparable. • Adsorption of benzimidazole derivatives followed Langmuir isotherm model. • MD simulations confirm the adsorption of the benzimidazole on the metal surface. • MD and DFT findings were in accordance with experimental results and explained the adsorption mechanism. [ABSTRACT FROM AUTHOR]

As long as several years, an ever-growing focus has been placed on the study of corrosion inhibitors due to their useful role in reducing the dissolution of metals in different corrosive environments. In that sense, and with the aim of inhibiting the corrosion effects of HCl acid on mild steel (MS), two bolaamphiphile surfactants, which are 1,6-bis((1H-benzimidazol-2-thioyl)hexane (BITH), and 1,12-bis((1H-benzimidazol-2-thioyl)dodecane (BITD) have been examined by means of electrochemical techniques, Density Functional Theory (DFT), Molecular Dynamics (MD) simulations and Radial Distribution Function (RDF). The corrosion-inhibiting aspects of two compounds have also been examined with the use of scanning electron microscope (SEM) technique. The inhibitory performance of both compounds is improved by increasing the inhibitor concentration, getting the better one to 303 K, and an optimal concentration of 5 × 10−4 M. Findings are suggestive that both molecules adsorbed on the surface of MS and created hydrophobic films providing an effective barrier into the surface. The results of PDP tests strongly imply that the studied compounds are acting as mixed-type inhibitors. Their adsorption isotherms are Langmuir type, and primary mechanisms involve both physical and chemical adsorption. The computational study was performed in an attempt to identify factors most associated with anti-corrosive properties of tested compounds. Unlabelled Image • New bolaamphiphiles compounds show good corrosion inhibition performances for MS in HCl. • Bolaamphiphiles compounds act as mixed inhibitor in 1.0 M HCl. • Surface morphology of mild steel was examined by SEM. • The adsorption process of bolaamphiphiles compounds follows Langmuir isotherm. • The experimental results were supported by DFT, Molecular dynamics and RDF. [ABSTRACT FROM AUTHOR]

The use of green and environmentally friendly substances is a contemporary scientific challenge and a key task for today's specialists in chemistry and technology-related fields. In this context, this research work involves the study of two new compounds named 1-benzoyl-2-(3,4-dimethoxyphenyl)-6,6-dimethyl-5,7-dioxaspiro [2.5]octane-4,8-dione (2-MPOD) and 1-benzoyl-6,6-dimethyl-2-(3,4,5-trimethoxyphenyl)-5,7-dioxaspiro [2.5]octane-4,8-dione (3-MPOD). The two compounds were synthesized and their inhibition properties for mild steel (MS) corrosion in 1.0 M HCl were first evaluated by means of experimental methods such as electrochemical impedance spectroscopy (EIS), weight loss (WL), in addition to potentiodynamic polarization (PDP) techniques, and also utilizing quantum chemistry studies and molecular dynamics (MD) simulations. For a description of the impact of molecules on the MS surface, the X-ray photoelectron spectroscopy (XPS) and scanning electron microscope equipped with an energy-dispersive spectrometer (SEM-EDS) have been performed. 2-MPOD and 3-MPOD were confirmed to be effective inhibitors in acidic solution and the highest resistance was achieved at 10-3 M concentration and 303 K. The adsorption of inhibitors on MS has been linked to both physical and chemical processes. The adsorption is in accordance with the Langmuir isotherm model. Quantum mechanical calculation results suggest that π-electrons in the aromatic ring and the lone-pair electrons in the methoxy group contribute to enhanced adsorption onto iron surface, leading to effective corrosion inhibition. Image 1 • Spirocyclopropane derivatives show good inhibition performances and follow the order: 3-MPOD > 2-MPOD. • The highest inhibition efficiency reaches as high as 98%. • XPS analysis confirmed the adsorption of inhibitor on carbon steel surface. • The adsorption process of spirocyclopropane molecules follow Langmuir isotherm. • Theoretical calculations provide in-depth understanding of the experimental results. [ABSTRACT FROM AUTHOR]

• XPS results show that tested pyrazolines have a good inhibition performance. • Surface morphology of mild steel was examined by SEM. • The adsorption process of pyrazoline molecules follow Langmuir isotherm. • The experimental results were supported by DFT, MD, and free volume theory. Iron and its alloys are commonly used materials in petroleum refining facilities. However, poor corrosion resistance is always a disturbing problem for these industries. Herein, we demonstrated the utility of two pyrazoline derivatives (PYRs), namely, 2-(4-(4,5-dihydro-3-(4-methoxyphenyl)-1H-pyrazol-5-yl)phenoxy)acetic acid (PYR-1) and 2-(4-(4,5-dihydro-3-p-tolyl-1H-pyrazol-5-yl)phenoxy)acetic acid (PYR-2) for enhancing mild steel (MS) resistance in 1.0 M HCl using chemical, electrochemical, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and computational techniques. Weight loss measurements revealed that the optimum concentration of inhibitors is 5 mM. The maximum inhibition efficiencies (based on electrochemical results) were obtained 94% and 88% for PYR-1 and PYR-2, respectively. Pyrazolines retard corrosion at room temperatures and show high inhibition efficiency at higher temperatures, (above 90% at 333 K). XPS results showed that these compounds could effectively inhibit acid attack through physical and chemical adsorption on the metal surface. PYRs adsorption onto the steel surface follows Langmuir adsorption model. Electrochemical results revealed that the new compounds could exhibit excellent corrosion inhibition performance and displayed mixed-type inhibition. The performances of inhibitor films and the potential mechanisms were also investigated theoretically using MD simulation, radial distribution function (RDF), mean square displacement (MSD) and free volume theory. The present results will be helpful to uncover the versatile importance of pyrazoline compounds in the corrosion inhibition process. [ABSTRACT FROM AUTHOR]

A relative investigation of various synthesized hydrazone derivatives was examined for their inhibitive impact on mild steel in 1 M HCl medium, using the measurements of weight loss and electrochemical procedures. The different parameters, for example, corrosion rate, inhibition efficiency, and surface coverage were estimated. The weight loss strategy demonstrates the rise in the inhibition efficiency on expanding the amount of inhibitor. The inhibition activity of the compounds was expected to happen by means of adsorption over the steel surface which abides the Langmuir isotherm model. The inhibitors are predicted to be mixed inhibitors i.e. influencing both cathodic hydrogen evolvement and anodic metal dissolution. The surface investigation strategies (SEM-EDX, AFM, and XPS) further validated that the corrosion hindrance happens because of the adsorption of the inhibitors over the metal/solution interface. Also, the outcomes of the theoretical approach supported all the experimental results by illustrating the similar trend of inhibition efficiencies of various hydrazones. • The studied inhibitors were synthesized from pyrazine derivatives. • They controlled the rate of corrosion by adsorbing on the mild steel surface. • Their adsorption was investigated by XPS and IR spectrum. • All the experimental results showed good agreement with DFT and MD study. [ABSTRACT FROM AUTHOR]