Mild Steel In HCl Solution Research Articles

Insights into Corrosion Inhibition Behavior of a 5-Mercapto-1, 2, 4-triazole Derivative for Mild Steel in Hydrochloric Acid Solution: Experimental and DFT Studies

A triazole heterocyclic compound namely 3-(4-ethyl-5-mercapto-1, 2, 4-triazol-3-yl)-1-phenylpropanone (EMTP) was examined for its corrosion protection of mild steel (MS) against 1 M hydrochloric acid medium using gravimetric techniques. EMTP exhibited excellent corrosion protection performance at low and high concentrations towards MS in HCl solution. Comparison of corrosion protection performance of EMTP and its parent triazole and temperature effects of on inhibition efficacy were also studied. EMTP has potential corrosion inhibitor for mild steel in 1.0 M hydrochloric acid solution with the highest protection efficacy of 97% at 303 K. The weight loss findings implied that EMTP protects the metal surface corrosion through the creation of a protective layer at the surface mild steel–corrosive solution interface. The inhibitive efficacy increases with the increase of inhibitor concentration and decreases with increased temperature. The adsorption of EMTP on the surface of MS follows Langmuir’s adsorption isotherm process. DFT method was conducted on EMTP molecule to calculate the quantum chemical parameters and to determine the relationship between the molecular structure of EMTP and protection performance. The molecular parameters, such as energy gap and frontier molecular orbital (highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO)), and the absolute electronegativity (χ) value from inhibitor molecules to unoccupied d-orbital of iron atoms on the mild steel surface were also determined and correlated with protection efficiency. The theoretical findings revealed that the protection performance of EMTP increased with the increase in HOMO energy, and the nitrogen, oxygen and sulfur atoms are most probable positions for bonding through giving electrons to the d-orbital of iron atoms on the mild steel surface.

A Machine Learning-Based QSAR Model for Quinolines Tested As Corrosion Inhibitors of Mild Steel in HCl Solution

The investigation of organic compounds as potential inhibitors of metal corrosion using several experimental and/or computational techniques has been well established in literature. Recent advances in the development of corrosion inhibitors has led to the exploration of quantitative structure activity relationship (QSAR) as a worthy alternative to the rigorous, sometimes expensive and time-consuming experimental/computational procedures. QSAR is a robust computational method that generates mathematical models that maps the structural features of organic compounds with their inhibition performances. The obtained mathematical models can then be further used to predict the chemical activity of new and untested organic molecules. Although linear and non-linear methods have been reported in developing QSAR models, only few works have explored the use of state-of-the-art artificial neural network (ANN). This study reports the development of QSAR models for sixty quinolines investigated as corrosion inhibitors for mild steel corrosion in 1 M HCl using both linear and non-linear modelling techniques. Density functional theory (DFT) and Dragon 7 software were used to generate molecular descriptors for model development and were reduced to a significant few using feature selection tools. The significant molecular descriptors were employed in model building using conventional multiple linear regression (MLR) and ANN modelling techniques. The developed models were evaluated using several statistical performance metrics and the ANN-based model was found to produce the best correlation between the predicted and experimental inhibition efficiencies. Furthermore, nine new quinoline molecules were theoretically designed and their inhibition efficiencies were predicted using the best developed ANN model.

Combined atomic-scale/DFT-theoretical simulations & electrochemical assessments of the chamomile flower extract as a green corrosion inhibitor for mild steel in HCl solution

This investigation parallels the others hoping to address the environmental predicaments. Dealing with the corrosion progression of steel, being in battle with a harsh condition (HCl), using the novel Chamomile flower extract (CFe) could embody the advantageous lies in the green molecules of plants. The morphological influences of this plant extract were studied by exploiting the power of FE-SEM, EDAX, AFM, and contact angle examinations. Results were demonstrative of the surface smoothness increment after CFe inclusion into the medium; smoothing the surface as well as lowering the iron dissolution. Besides, the surface was characterized via GIXRD as well as Raman spectroscopy. In addition, the adsorption of the inhibitor was examined through UV–Vis analysis. The existence of functional groups like C = O and C = C, the reduction of iron dissolution, and the graphene-like compounds' existence confirmation on the metal surface, all subsequent to CFe loading, were the outcome of these assessments. The EIS and potentiodynamic polarization (PP) tests were performed. The outcome showed that the CFe could inhibit the corrosion proliferation substantially especially when the steel was exposed to 600 ppm solution for 8 h; a 98% inhibition efficiency was obtained. The calculations exhibited the CFe mixed inhibitive characteristic and Langmuir was the adsorption isotherm strategy of the studied inhibitor. Finally, the study was further expanded into the theoretical point of view in which the adsorption of inhibitor molecules on the surface was confirmed; in agreement with the experimental outcome.

Effect of Temperature on the Corrosion Inhibition of 4-ethyl-1-(4-oxo-4-phenylbutanoyl)thiosemicarbazide on Mild Steel in HCl Solution

Brugada syndrome is a syndrome causing abnormal electrolyte and electrocardophysiology. In an attack of Brugada syndrome, a patient might sleep and die without any other clear causes. Genetic underlying Brugada syndrome is widely studied. SCN5A p.R965C is a common genetic variant seen in an endemic area of Burgarda syndrome such as Southeast Asia. An assessment of the impact of SCN5A p.$965C was performed using standard nanomolecular quantum calculation. According to the assessment, a decreased molecular weight due to mutation is observed, implying an increased SCN5A expression. The nanomolecular charge well explains the clinical problem of Brugada syndrome.

Novel carbon dots as efficient green corrosion inhibitor for mild steel in HCl solution: Electrochemical, gravimetric and XPS studies

Eco-friendly, good water soluble and inexpensive, carbon dots (CDMU and CDMH) were synthesized, characterized and applied as corrosion inhibitor for mild steel (MS) in 15% HCl solution. The characterization of both inhibitors was carried out by FTIR, UV–vis, photoluminescence, XPS and TEM. The average size of CDMU and CDMH were found as 2.03 and 2.5 nm, respectively. The inhibitive effect of CDMU and CDMH was evaluated by weight loss measurement, electrochemical impedance spectroscopy and potentiodynamic polarization measurement. Both CDMU and CDMH exhibited 97.89 and 90.10% of inhibition efficiency, respectively, at 100 mg/L concentration and 303 K temperature. Adsorption of CDMU and CDMH on MS surface followed Langmuir adsorption isotherm. The surface morphology of uninhibited and inhibited MS specimens was studied by the FESEM, AFM and XPS analysis.

Mild steel corrosion inhibition in hydrochloric acid using cocoa pod husk-Ficus exasperata: extract preparation optimization and characterization

This paper aimed at studying optimization of cocoa pod-Ficus exasperate (CP-FE) extract preparation as mild steel anticorrosive agent in hydrochloric acid solution using central composite design as optimization tool. Maximum inhibition efficiency of 95.42% was obtained at ethanol volume, extraction time, CP-FE mixing ratio and CP-FE mass of 500 ml, 48 hr, 5 and 100 g respectively. Coefficient of determination value of 0.9674 between experimental and predicted values suggested that the model developed was exact. Optimum predicted point for CP-FE extract preparation by CCD was 62.02 ml, 9.51 hr, 3.42 and 75.68 g for the ethanol volume, extraction time, CP-FE mixing ratio and CP-FE mass respectively. SEM images revealed acid attack on mild steel surface. Adsorption of CP-FE extracts on mild steel surface prevents acid attack. FTIR revealed presence of carboxyl (-COOH) and hydroxyl (-OH) functional groups. EDS revealed high iron composition on mild steel surface in the presence of CP-FE extracts. Loss of Fe2+ into free HCl solution was observed from the AAS result. Conclusively, mixed cocoa pod-Ficus exasperate extracts exhibited effective corrosion inhibitory attributes for mild steel in HCl solution.

Akebia trifoliate koiaz peels extract as environmentally benign corrosion inhibitor for mild steel in HCl solutions: Integrated experimental and theoretical investigations

In this account, pectin components were obtained from akebia trifoliate koiaz peels with the acid extraction technology. The chemical constituent of the akebia trifoliate koiaz peels extract (ATKPE) was analyzed and its anti-corrosion performance for mild steel in HCl medium was investigated by electrochemical methods, surface analysis and theoretical calculations. Experimental results show that ATKPE exhibits excellent corrosion inhibition characteristic, and its inhibition efficiency can be as high as 90% when the concentration of ATKPE is 800 mg/L. Electrochemical measurements show that ATKPE is a mixed-type corrosion inhibitor consisting with Langmuir adsorption model. In addition, SEM, AFM and contact angle observations suggests that the ATKPE may attach firmly to the metal surface by forming a barrier film. XPS and ATR-FTIR results further verify the bonding interaction between the functional groups and steel substrate. Meanwhile, quantum chemical calculations and molecular dynamics (MD) simulations were performed to reveal the inhibition mechanism at molecular/atomic level. In brief, our findings demonstrate a novel environmentally benign, efficient corrosion inhibitor for steel protection in acidic media.

Investigations on Corrosion Inhibitory Effect of Newly Quinoline Derivative on Mild Steel in HCl Solution Complemented with Antibacterial Studies

This study analyzed the corrosion inhibitory effects and the antibacterial action of the quinoline derivative, namely N'-(2-hydroxybenzylidene)-2-(quinolin-8-yloxy)acetohydrazide (NHQA). NHQA prevention of corrosion behavior was investigated using weight loss experiments on mild steel coupons in hydrochloric acid. Weight loss tests achieved improved inhibition performance for NHQA, and the high inhibitor efficiency was reached at 303 K, of 93.4 percent at 500 ppm NHQA. Moreover, the effect of immersion time on carbon steel corrosion was investigated using strategies for weight loss. The NHQA mechanism for corrosion inhibition was also examined. These findings confirm that the NHQA molecules can be used in industrial applications as a possible corrosion inhibitor. In an aqueous solution, the synthesized compound (NHQA) can also be used as an antimicrobial agent. The microbial inhibitive efficacy of NHQA against Gram-positive (Staphyloccocus aureus) and Gram-negative bacteria (Escherichia coli, Proteus vulgaris, Klebsiella pneumoniae, and Pseudomonas aeruginosa) was evaluated employee a disc diffusion technique. NHQA has considerable inhibition efficacy toward all investigated bacteria.

Electrochemical and surface analytical studies of transition metal bipyridine dicarboxylic acid complexes as corrosion inhibitors for a mild steel in HCl solution

The 2,2′-bipyridine-3,3′-dicarboxylic acid (bpda) and its transition metal complexes including Ni(bpda)2, Zn(bpda)2 and Mn(bpda)2, were synthesized and tested as corrosion inhibitors for a carbon steel in 0.5 M HCl solution by electrochemical tests and surface analyses. The electrochemical results indicate that the inhibition efficiencies increase with the concentration of corrosion inhibitors. The complexes exhibit higher inhibition efficiencies compared to the bpda ligand, among which Ni(bpda)2 is the most effective for inhibiting corrosion. The corrosion morphology observation further evidences the superior corrosion inhibition performance of the three complexes. Fourier transform infrared and X-ray photoelectron spectroscopy analyses confirm the spontaneous adsorption of all four inhibitors on the steel surface, and the adsorption analysis suggests a combined physisorption and chemisorption mechanism. Accordingly, the superior corrosion inhibition performance of the three complexes could be attributed to their good adsorption abilities.

Insight into the corrosion inhibition of new amino-acids as efficient inhibitors for mild steel in HCl solution: Experimental studies and theoretical calculations

Two organic compounds namely, Phenylalanine (P1) and Aspartic acid (P2) have been studied for inhibiting mild steel (MS) corrosion in molar hydrochloric acid solution. The Anti-corrosion activity has been evaluated using electrochemical impedance spectroscopy (EIS), potentio-dynamic polarization (PDP), Density Functional Theory (DFT), Monte-Carlo Simulation (MCS) and Molecular Dynamic Simulation (MDS). The corrosive solutions were analyzed by UV–visible spectrometry (UV–vis). The surface of MS after the corrosion tests was analyzed by Scanning Electron Microscopy (SEM). The inhibition efficiency of the two amino acids (P1 and P2) increased by the increase in their concentration and reached an optimal value of 87% and 89% for P1 and P2 respectively. Their adsorption mechanism was consistent with the isotherm Langmuir. Polarization measurements led to the conclusion that the two compounds act as mixed inhibitors. UV–visible shows that the addition of the two compounds decreases the dissolution of ferric ions in the corrosive solutions. Scanning Electron Microscopy (SEM) images show that both inhibitors were well adsorbed on the MS surface. Computational approaches of the metal-inhibitor interaction type were studied and interpreted using DFT, MCS and MDS.

Green corrosion inhibition of mild steel in HCl medium using leaves extract of Arbutus unedo L. plant: An experimental and computational approach

In this study, leaves extract of Arbutus unedo L. plant was used as a green corrosion inhibitor of mild steel in hydrochloric acid. The aqueous extract is rich in polyphenol and in particular flavonoid compounds as determined by the quantitative aluminum chloride colorimetric method. The n-butanol extract shows the highest concentration of total phenol and total flavonoid contents with 219.46 GAE mg/g extract and 174.66 mg QE/g of dry extract, respectively. Electrochemical impedance spectroscopy and potentiodynamic polarization were used as experimental measurements to confirm the anti-corrosion performances of the extract of plant leaves at different temperatures. The addition of extract plant even at low concentration increases significantly the inhibition efficiency with a maximum of 91.72% at 298 K for 0.5 g/L of leaves extract. Surface analysis was performed to attest the presence of the protected film on the surface of mild steel in HCl solution. The calculated ΔG0ads value (−24.441 kJ/mol) confirmed a spontaneous mixed chemical and physical adsorption of leaves extract compounds on the metal surface. The pKa analysis attested that the two leaves extract compounds, quercetin and catechin, exist in the neutral form in an acidic environment. Moreover, density functional theory and molecular dynamic simulation were also conducted to support the high inhibition efficiency results obtained by the experimental tests and to propose the adsorption mechanism.

Synthesis, structural analysis and corrosion inhibition application of a new indazole derivative on mild steel surface in acidic media complemented with DFT and MD studies

A great deal of consideration has been given to the development of new compounds having diverse functionality. In this report, a new indazole derivative bearing a nitro group, namely 2-(3-chloro-5-nitro-1H-indazol-1-yl) acetic acid (CNIA) was synthesized, characterized, and used as corrosion inhibitor for mild steel (MS) in 1.0 M HCl. A full characterization of the prepared compound was performed using single‐crystal XRD, FT-IR, and UV–vis measurements; its corrosion inhibition properties were experimentally evaluated by potentiodynamic polarization (PDP) curves as well as electrochemical impedance spectroscopy (EIS) measurements, and theoretically by Density Functional Theory (DFT) and molecular dynamics (MD) simulations. Scanning electron microscope (SEM) was used to examine the morphology of the corroded metal surface before and after the inhibition. The findings demonstrated that the application of CNIA significantly reduced the corrosion rates of MS. The corrosion inhibition ability of the synthesized compound was also identified at a lower concentration in all experiments, reaching a maximum of 89 % at 10−3 mol/L. The results of potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) confirmed that CNIA could be categorized as a mixed type inhibitor with an increased polarization resistance at higher concentrations. Langmuir's adsorption isotherm was found to fit the adsorption of CNIA molecules on the MS surface. SEM photographs showed obvious less-corroded morphologies in the presence of the CNIA as compared to untreated MS surface. Theoretical calculations were proposed to explain the mechanism of the inhibition effect and found that it is due to the donor/acceptor properties of the inhibitor and its parallel disposition over the steel surface. The present compound could be a promising corrosion inhibitor for mild steel in HCl solutions, and showed a corrosion inhibition property that is superior to similar compounds.

Biomass of Microalgae Chlorella sorokiniana as Green Corrosion Inhibitor for Mild Steel in HCl Solution

Biomass of Microalgae Chlorella sorokiniana as Green Corrosion Inhibitor for Mild Steel in HCl Solution

S-Thiazine as effective inhibitor of mild steel corrosion in HCl solution: Synthesis, experimental, theoretical and surface assessment

Abstrat This potential work presents a new organic molecule as a corrosion inhibitor of mild steel in HCl solution (1.0 M HCl).The organic molecule was elucidated by IR, 1H NMR and 13C NMR spectroscopy.The corrosion inhibiting effect was achieved by techniques electrochemical techniques such as Potentio-dynamic polarization (PDP) and impedance spectroscopy (EIS).The surface of the steel after corrosion tests has been identified by scanning electron spectroscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscope (AFM) spectroscopy. The experimental studies were confirmed by the calculations of density functional theory (DFT) and Monte Carlo simulations (MC). The theoretical, experimental studies and analytical techniques clearly show that this molecule is a good corrosion inhibitor (91 %) of steel in HCl solution. The polarization studies show that this inhibitor acts as a mixed type inhibitor. The thermodynamic parameters show that this molecule chemically adsorbed on the surface of the steel following the isotherm of Langmuir.

Investigation of Dolichandra unguis-cati leaves extract as a corrosion inhibitor for mild steel in acid medium

Electroactive compounds extracted by the leaves of Dolichandra unguis-cati (DUCLE) have been utilized for corrosion studies on mild steel in HCl solution. Mass-loss, Potentiodynamic Polarization, and Electrochemical impedance measurements were applied in the evaluation. The DUCLE forms a light coating on the surface of the metal, which helps in controlling the corrosion. The percentage inhibition performance, cathodic Tafel slopes, anodic Tafel slopes, and corrosion current density were evaluated. The maximum %ηW observed was 93.61 in 1 ​M HCl at 0.76 (g/L) concentration of DUCLE inhibitor after 3 ​h of immersion at 300 ±1K. DUCLE functions as a mix type inhibitor and, DUCLE adsorption on the mild steel fits the Langmuir isotherm. The inhibitor potential for mild steel was acquired by various concentrations of inhibitor. Thermodynamic specifications disclose the corrosion inhibition process was spontaneous and exothermic. The values of ΔGadso lie between −31.585 and −32.45 ​kJ mol−1for 1 ​M HCl. FT-IR, AFM, SEM, and contact angle techniques were used to characterize the DUCLE inhibitor's relationship on the surface of mild steel.

A joint experimental and theoretical investigation of the corrosion inhibition behavior and mechanism of hydrazone derivatives for mild steel in HCl solution

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.

Comprehensive assessment of corrosion inhibition mechanisms of novel benzimidazole compounds for mild steel in HCl: An experimental and theoretical investigation

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.

The corrosion behavior of the SnO2-coated mild steel in HCl solution at different temperature

In the present work, SnO2 was successfully coated on mild steel (MS) by the sol–gel method at different times (15,30,45 min). These coatings were developed to improve the performance of corrosion protection of MS in a 0.5 M HCl solution. The morphological and structural characterization of obtained electrodes was investigated with the help of characterized by Field-emission scanning electron microscopy (FE-SEM) and the contact angle. The corrosion behavior of uncoated and at 15,30,45 min SnO2-coated MS electrodes were investigated by open circuit potential (OCP)–time, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques in 0.5 M HCl solution at 20–50 °C. Moreover, the potential of zero charges (pzc) of MS was determined using the EIS technique. EIS results indicated that the maximum inhibition efficiency (85%) during the coating time of 30 min at 30 °C. As a result, the SnO2 film effectively protected on the MS against corrosion and reduced its corrosion rate in the HCl solution. Highlights The SnO2 was coated on MS electrode at 15, 30, 45 minutes by a simple sol-gel method. The surface morphologies were characterized by FE-SEM and the contact angle. The corrosion behaviors of samples were investigated by electrochemical techniques. The SnO2 provides good corrosion protection against the attack of corrosive media.

Carbon Dots as Green Corrosion Inhibitor for Mild Steel in HCl Solution

AbstractTwo carbon dots namely, S, N co‐doped (CD1) and N doped (CD2) were synthesized by solvothermal treatment of pyromelletic acid in presence of thiourea, urea and DETA at 180 °C. The synthesized carbon dots were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Transmission electron microscopy (TEM) and Raman spectroscopy analysis. The dimension of synthesized carbon dots were found in the range of 1.63 nm to 2 nm with significant graphitic carbons. These carbon dots (CD1 and CD2) were used as green corrosion inhibitor to mitigate corrosion of mild steel (MS) in 15 % HCl solution using gravimetric and electrochemical methods. Studied carbon dots, CD1 and CD2 exhibited inhibition efficiency of 96.40 and 90.00 %, respectively, at 100 ppm concentration and 303 K temperature. The observed corrosion inhibition occurs due to adsorption of the carbon dots to the MS surface. Both the carbon dots follow Langmuir adsorption isotherm model and show physisorption on the MS surface. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis was used to study the morphology of the uninhibited and inhibited surface of the sample. The interaction of the carbon dots and composition of adsorbed layer on the MS surface was confirmed using X‐ray photoelectron spectroscopy (XPS). The XPS analysis revealed that heteroatoms present in the structural moiety of the carbon dots efficiently binds on the MS surface.

Nitrogenated derivatives of furfural as green corrosion inhibitors for mild steel in HCl solution

The ability of nitrogenated derivatives of furfural to act as corrosion inhibitors for mild steel in 1molL−1 HCl solution was evaluated using weight-loss measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The imine 2-((furan-2-ylmethylene)amino)ethan-1-ol (1) and the mixture of 2-(furan-2-yl)-1,3-oxazinane and 3-((furan-2-ylmethylene)amino)propan-1-ol (2a+b) presented, respectively, 81.9% and 84.4% of inhibition efficiency towards the mild steel acidic corrosion at 5×10−3molL−1, room temperature and 2-h immersion time. Polarization curves showed more effective inhibition in the cathodic process. EIS plots indicated an increase in the polarization resistance with enhancement of inhibitor concentration. The adsorption of the evaluated inhibitors obeyed the Langmuir adsorption isotherm. The ΔG°ads and ΔH°ads values obtained suggest a physical nature adsorption of inhibitors (1) and (2a+b). The physisorption could be explained by the coulombic interaction between the protonated forms of the inhibitor molecules due to the acid medium with the negatively charged surface. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface morphologically and chemically, respectively. Quantum chemical calculations were applied to correlate electronic structure parameters of inhibitors with their corrosion inhibition efficiency.