Corrosion Inhibition Of Mild Steel Research Articles

Corrosion inhibition of two tetracycline‐based expired antibiotics as eco‐friendly inhibitors for mild steel in 1M HCl solution

AbstractTwo expired Tetracycline‐based antibiotics (Oxytetracycline and Tetracycline) were utilized as eco‐friendly corrosion inhibitors for mild steel in 1M HCl solution, employing weight loss analysis, electrochemical measurements, scanning electron microscopy, and so on. The effect and mechanism were discussed using thermodynamic modeling, quantum chemical calculation, molecular dynamics simulation, and so on. The corrosion inhibition rate (η) increases with higher concentration and temperature, leading to reduced heat absorption and increased order degree. The of Oxytetracycline and Tetracycline was 96.14% and 97.92% at 323.15 K of 2 × 10−4 mol L−1, respectively. The key factors affecting η in the kinetic model parameters vary at lower concentrations. Both of them belong to cathodic corrosion inhibitors and undergo Langmuir spontaneous adsorption processes involving both physisorption and chemisorption. The disparity in energy levels between the highest occupied molecular orbital and lowest unoccupied molecular orbital, global hardness, electronegativity, molecular polarizability, dipole moment, and transfer electron number are key factors that enhance a corrosion inhibitor's ability to adsorb chloride ions.

Optimization and Predictive Modelling of Gravimetric Corrosion Characteristic of Irvingia Gabonensis Leaves Extracts as Anti Corrosion Inhibitor of Mild Steel in HCl Solution

In this research, the optimization and predictive modeling of gravimetric corrosion characteristics of Irvingia gabonensis leaf extracts (IGLE) as an anti-corrosion inhibitor of mild steel in hydrochloric acid were investigated. Design expert software version 11 were used to analyze the corrosion inhibition-related process characteristics, such as inhibition efficiency, corrosion rate, and weight loss, and their relationships. An effort were made to obtain the optimal conditions for these corrosion inhibition-related process characteristics. Weight loss measurement and design methodology were used for the evaluation of the inhibition efficiency of IGLE for mild steel in HCl. The corrosion inhibition process variables were optimized and predictive regression models were developed using Box-Behnken tool of the Response Surface Methodology (RSM). The findings showed that there were a good fit between the model predictions and the experimental results. The quadratic models developed were significant with P value less than 0.05. The research established an inhibition efficiency of 88.9%, a corrosion rate of 0.143mm/yr, and a weight loss of 0.02 g, which were obtained at the optimum conditions of an extract concentration of 0.6 g/L, an immersion time of 16 hrs, and a temperature of 298K.Therefore, the models were considered ideal for prediction with a confidence level of 95%, and the optimal combination is suitable for the corrosion inhibition process design. Hence these models can be recommended for applications such as oil well acidizing and pickling pipelines.

Electrochemical analysis of corrosion inhibition shallot leaf (Allium cepa) extract on mild steel in acidic medium at different immersion times

Plant derivatives as eco-friendly corrosion inhibitors are currently greatly interested in much research. Shallot leaf (Allium cepa) was utilized in 0.1M HCl as a corrosion inhibitor of mild steel. The functional groups present in the macerated extract were subsequently identified using an FTIR test. Electrochemical tests such as tafel polarization and EIS were carried out to determine the corrosion inhibition performance of shallot leaf extract on the SS400 steel. The results of the electrochemical analysis show that shallot leaf extract can inhibit mild steel up to 94% at a concentration of 500 ppm. Furthermore, the addition of SLE reduces surface damage of mild steel, which can be seen by SEM.

Experimental Study on Adsorption and Corrosion Inhibition Properties of <i>Urena lobata</i> Leaves Extract on Mild Steel in Acidic Medium

The corrosion inhibitive effect of <i>Urena lobata</i> leaves extract on mild steel in 1M HCl solution was investigated via gravimetric, Electrochemical and Surface analyses. Adsorption isotherms were investigated using the Langmuir and Freundlich plots. Phytochemicals of the extract were investigated using Gas Chromatography-Mass Spectrometric (GC-MS) technique. The effect of the leaves extract through immersion time, temperature and concentration on the corrosion inhibition were obtained. The results obtained showed that the increase in extract’s concentration increased the inhibition efficiency and the protection was more on the surface of the metal at lower temperature. Maximum inhibition efficiency of 95.8% was obtained at 2.5g/L extract concentration. Corrosion rate of mild steel increased with temperature increase in the acidic solution. The adsorption process reduced as temperature increased thereby indicating physisorption. The Langmuir isotherms gave the best fit indicating chemisorption. Physical adsorption was confirmed for the leaves extract from observations of inhibition efficiency with temperature, activation energy and enthalpy of adsorption values. Hence indicating that the plant extract has mixed properties. The electrochemical results confirmed the inhibitory ability of the plant extract. The inhibition efficiencies (% IE) were attributed to the phytochemical components (alkaloids, saponins, flavonoids, tannins, cynagenic glycosides) present in the extract. The extracts of <i>Urena lobata</i> are effective corrosion inhibitors of mild steel.

Oleaster Leaf Extract: A Potential Environmentally Friendly Inhibitor for Mild Steel

In this research, the potential of Elaeagnus angustifolia tree leaf extract as a green corrosion inhibitor for mild steel in hydrochloric acid solution was examined. The stock concentration of the aqueous extract was determined to be 0.38% (w/v). Other experimental solutions were created by diluting four different extract concentrations in aggressive solution. Experimental measurements, including linear polarization (LPR), electrochemical impedance spectroscopy (EIS), and semi-logarithmic current potential curves by Tafel extrapolation method, were employed to validate the corrosion inhibition effects of the plant leaf extract at varying concentrations. Notably, oleaster leaf extract demonstrated a corrosion protection of over 80% for mild steel, even at low concentrations, attributed to its abundance in secondary metabolites such as polyphenols and flavonoids. The atomic force microscopy (AFM) surface maps provide robust evidence for the electrochemical measurement data.

Unveiling the potent corrosion-inhibiting power of Ammophila arenaria aqueous extract for mild steel in acidic environments: An integrated experimental and computational study

Plant extracts have emerged as potent inhibiting compounds for metallic corrosion, offering numerous advantages including simple accessibility, low toxicity, eco-friendliness, biocompatibility, effectiveness, and renewability. In this study, the potential of Ammophila arenaria extract as a green corrosion inhibitor for mild steel in 1.0 M HCl over the concentration range of 25–700 ppm was evaluated, using various electrochemical analyses such as Open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Results revealed a notable reduction in the corrosion rate of steel, particularly at 700 ppm, where Ammophila arenaria extract demonstrated its highest inhibition efficiency, reaching 83.67% for polarization and 84.32% for EIS. The cathodic and anodic polarization curves indicated that the aqueous extract of Ammophila arenaria functions as a mixed-type inhibitor. The thermodynamic analysis revealed a negative Gibbs free energy value (∆Gads°), suggesting spontaneous physisorption as the predominant adsorption mechanism. To delve into the inhibition mechanism at the molecular level, the surface morphology of mild steel exposed to 1.0 M HCl solutions, both in the absence and presence of Ammophila arenaria aqueous extract, was scrutinized through Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Theoretical techniques, including Quantum Calculation Theory, Non-Covalent Interaction (NCI), and Atom In Molecule (QTAIM), were concurrently employed, providing valuable insights into molecular-level interactions. Remarkably, the computational studies complemented and corroborated the experimental data. These comprehensive results significantly contribute to the understanding of Ammophila arenaria extract's corrosion inhibiting properties, endorsing its potential as a sustainable and environmentally friendly corrosion inhibitor suitable for diverse industrial applications. The synergistic integration of experimental and computational approaches establishes a robust foundation for future endeavors in the field of green corrosion inhibitors.

Excellent performance of amoxicillin and potassium iodide as hybrid corrosion inhibitor for mild steel in HCl environment: Adsorption characteristics and mechanism insight

Combining inhibitors is a key strategy to increase inhibitory efficacy because of synergistic effects. In this study, a green pharmaceutical inhibitor, amoxicillin (AML), was screened and compounded with potassium iodide (KI) to successfully obtain a synergistic and highly efficient green inhibitor. The results revealed that AML/KI have excellent anticorrosion ability for Q235 steel in 1 M HCl medium. At the optimal concentration ratio of 2 mM AML +5 mM KI, the inhibition efficiency was up to 97.7%, which was significantly higher than that of AML alone (57.4%). The hybrid inhibitor remarkably hinders the corrosion process by inhibiting both the cathodic and anodic reactions. Scanning electron microscopy, electron dispersive spectroscopy, contact angle measurement, ultraviolet–visible spectrometry and X-ray photoelectron spectroscopy, as well as Fourier transform infrared spectroscopy, results further confirm the outstanding inhibitory effect and the formation of synergistic adsorption films. Through density functional theory (DFT) calculations, we discovered that the KI salt significantly enhances the adsorption characteristics of AML/KI on the Fe surface, which is consistent with the experimental findings. This research paves the way for a new breed of green hybrid corrosion inhibitors to be created.

Corrosion inhibition of mild steel in acidic environments: Mechanistic insights and protective effects of azo-cum inhibitor

An examination was conducted on a newly developed compound named N1-(coumarin-7-yl) amidrazone (Azo-Cum) to assess its impact on the corrosion of mild steel (MS) in a 1 M hydrochloric acid (HCl) solution. Various analytical techniques, including weight loss, potentiodynamic polarization (PDP), impedance spectroscopy (EIS), cyclic voltammetry (CV), UV–visible spectroscopy, scanning electron microscopy (SEM), and AFM, were employed to evaluate the inhibitory efficiency of the compound. The findings indicated that inhibition efficiency rose with higher concentrations but decreased with elevated temperatures. According to weight loss analysis, the optimal concentration of the new eco-friendly inhibitor (5 ×10−4 M) exhibited a maximum efficiency of 89.26%. Polarization studies disclosed that Azo-Cum acted as a mixed-type inhibitor with a cathodic predominance. The adsorption of the inhibitor on the MS surface followed the Langmuir adsorption isotherm. Additionally, the study explored the synergistic effect of Azo-Cum in combination with KI on MS corrosion in a 1 M HCl (Blank) solution using potentiodynamic polarization measurements. The results identified concentration ranges that demonstrated antagonistic inhibition. Density functional theory (DFT) and molecular dynamic simulation (MD) calculations were performed to investigate the correlation between molecular and chemical reactivity.

Mechanistic insights into the corrosion inhibition of mild steel by eco-benign Asphodelus Tenuifolius aerial extract in acidic environment: Electrochemical and computational analysis

This study explores the novel application of Asphodelus Tenuifolius aerial extract (ATAE) as a corrosion inhibitor for mild steel in a 0.5 M HCl acidic environment. By utilizing techniques such as electrochemical measurements, gravimetric analysis, SEM, and CA assessments, the inhibitory potential of ATAE has been comprehensively evaluated. The results revealed a concentration-dependent enhancement in corrosion resistance, classifying ATAE as a mixed-type inhibitor by measuring the anodic (βa) and cathodic (βc) polarization slope values of 108.89 and −129.33 mV/dec. The peak inhibition efficiency was observed at 250 ppm, reaching an impressive IE% of 94.40 % at 298 K (Kelvin). The electrochemical analysis demonstrated a significant increase in charge transfer resistance (Rct) and polarization resistance (Rp) values, coupled with a decrease in Constant Phase Element (CPE.Yo) value to 162.94 μF, indicating heightened corrosion inhibition potential. Additionally, Theoretical calculations emphasized a strong interaction between ATAE and mild steel surface, characterized by a low energy gap (ΔE), indicating excellent anti-corrosion abilities at the micro-level. This study positions ATAE as a promising corrosion inhibitor, offering insights for further research in corrosion prevention strategies using a sustainable corrosion inhibitor.

Harnessing machine learning and virtual sample generation for corrosion studies of 2-alkyl benzimidazole scaffold small dataset with an experimental validation

The present work deals with the development of a QSAR model based on Artificial Neural Network (ANN) algorithm for the prediction of inhibition efficiencies of 2-alkyl benzimidazole scaffold-based corrosion inhibitors for mild steel corrosion in 1 M HCl. The small dataset problems have been dealt with a Virtual Sample Generation (VSG) methodology using CTGAN algorithm, and credibility and generalizability of the proposed ANN+VSG model has been verified through experimental validation. Two new 2-alkyl benzimidazole scaffold-based corrosion inhibitor compounds namely EBIMOT and PBIMOT, were synthesised, their inhibition efficiencies were experimentally obtained, and the values showed a high resemblance with the predicted one by the model with good accuracy. Synthetic data embedding to the training samples enhances the model's recognition capacity of feature-target relationship and hence stabilizing and improving the correlation of the chemical quantum descriptors with the inhibition efficiency. This proposed method strengthens the prospect of ML for developing material designs, especially in the case of small datasets at a much cost-efficient, user-friendly, and accurate manner and can open doors to new and unexplored venues in the intersection of material science and computational intelligence.

Synthesis and investigation of two new compounds (2-(methoxymethyl)−1- phenyl-2-propen-1-one and 2-(methoxymethyl)−1-(4-methoxyphenyl) - 2-Propen-1-one) as corrosion inhibitors for mild steel in acidic solutions at elevated temperature.

This study evaluated the performance of two newly synthesized organic corrosion inhibitors using the gravimetric weight loss method in hydrochloric acid (HCl), methanesulphonic acid (MSA), and a combination of HCl and MSA in the presence of different corrosion inhibitor (CI) concentrations at temperatures of 30 °C to 90 °C. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) studies were carried out for an in-depth study of corrosion mechanisms. Following the weight loss study, the percentage inhibition efficacies of C1 and C2 at 300 ppm concentrations were found to be ≈ 100% at 30 °C, 40 °C and 60 °C in 15 wt% HCl, 10 wt% MSA, and a combination of both acids (15 wt% HCl and 10 wt% MSA). The performances of C1 and C2 deteriorated slightly when tested in 10 wt% MSA at 90 °C. The synthesized CIs still showed a very high inhibition efficiency in the presence of 15 wt% HCl and a mixture of acids (HCl and MSA) at 90 °C. PDP studies indicated that both C1 and C2 act as anodic inhibitors. The inhibition efficiencies obtained from the PDP and EIS studies agreed with the weight loss study. The high value of Kads and the negative ∆Gads value suggests that C1 and C2 corrosion inhibitors have a strong and spontaneous tendency to chemisorb onto the mild steel surface. SEM-EDX studies proved the formation of a uniform, protective corrosion inhibitor film on the metal surface. Both C1 and C2 have been proven suitable for high-temperature corrosion applications.

Corrosion inhibition of mild steel in 1 M HCl using water soluble chitosan derivative of vanillin

The water-soluble chitosan derivative (WSCD) was made by mixing chitosan with sodium hydroxide, treating the mixture with chloroacetic acid, and then forming a Schiff base with vanillin in an acidic medium. In this study, we examined the corrosion-inhibiting ability of a WSCD on mild steel surfaces in acidic environments. Weight loss, EIS, PDP, LPS, and OCP measurements were used to study the corrosion resistance on mild steel surfaces in 1 M HCl solutions with known concentrations of WSCD. The results show that WSCD functions effectively as a mixed-type anodic and cathodic inhibitor, providing 87 % corrosion inhibition efficiency at 75 ppm. Using SEM to investigate the morphology of corroded mild steel with and without varying amounts of WSCD, impedance measurements show the development of a thin film of inhibitor on the metal surface, the extent of which increases as the inhibitor concentration rises. The WSCD molecule first adsorbs on mild steel and follows Langmuir adsorption isotherm. It is found that the (∆Gads0)adsorption's free energy is −17.473 kJ/mol. The contact angle measurements confirm that the hydrophobicity of the metal surface has increased as a result of the inhibitor's thin film development.

Evaluation of Glebionis coronaria L. flower extract as a novel green inhibitor for mild steel corrosion in acidic environment

Evaluation of Glebionis coronaria L. flower extract as a novel green inhibitor for mild steel corrosion in acidic environment

1,4-Phenylenediamine-based Schiff bases as eco-friendly and efficient corrosion inhibitors for mild steel in HCl medium: Experimental and theoretical approaches

The application of Schiff bases as corrosion inhibitors is one of the economic, practical, and effective techniques to retard metal corrosion in aggressive environment. The continuous exploration of novel, lower-cost, more efficient, and eco-friendly corrosion inhibitors is an everlasting pursuit of excellence. In this study, two 1,4-phenylenediamine-based single Schiff base isomers, (E)-4-((pyridin-2-yl-methylene)amino)aniline (PMAA2) and (E)-4-((pyridin-3-ylmethylene)amino)aniline (PMAA3), were synthesized by one-step reaction. The corrosion inhibition mechanism and structure–activity relationship of PMAA2 and PMAA3 for mild steel in HCl solution were analyzed using electrochemical and weight loss experiments, morphology analysis, density functional theory (DFT) calculation, and molecular dynamic (MD) simulation. The results demonstrated that the corrosion inhibition efficiency of PMAA2 and PMAA3 exhibited an increasing trend with the elevation of inhibitor concentration while showing a slight decrease with the temperature rise. The optimal corrosion inhibition efficiency for 800 mg L−1 PMAA2 and PMAA3 in 1.0 mol L−1 HCl solution is 90.88 % and 91.78 % at 303 K respectively by using weight loss experiment. The electrochemical experiment results indicated that PMAA2 and PMAA3 are mixed-type corrosion inhibitors, with a preponderant control of anodic dissolution. Both the thermodynamics of adsorption and the kinetic of corrosion reaction were evaluated and discussed in detail. Their adsorption upon mild steel complies with Langmuir adsorption isotherm and is involved in phys- and chemisorption concurrently. The results from surfacemorphologyanalysis exhibited that a dense protective film on the surface of mild steel is formed through inhibitor adsorption, which results in changes in the hydrophilicity and hydrophobicity of the metal surface. The calculations of DFT and Fukui index also indicated that both the neutral and pronated species of PMAA2 and PMAA3 possess donor–acceptor interactions with the surface iron atoms through both forward and back-donations. Furthermore,MD simulations further revealed that the neutral molecules as neat-flat and parallel orientation are adsorbed strongly on the Fe (110) surface but the pronated species perform in bent fashion on the Fe (110) surface. Based on the experimental analysis and the theoretical calculation, a possible adsorption and corrosion inhibition mechanism was proposed rationally. These findings display good correlations between the experimental investigation and the theoretical computation and are of fundamental importance to understanding the adsorption and corrosion inhibition mechanisms of the inhibitors.

Exploring corrosion protection for mild steel in HCl solution: An experimental and theoretical analysis of an antipyrine derivative as an anticorrosion agent

AbstractThe corrosion of mild steel in HCl solution remains a critical issue in various industrial applications. In the quest for effective corrosion inhibitors, 4‐(2‐Hydroxy‐3‐Methoxybenzylideneamino) antipyrine (HMBA) has emerged as a promising candidate. This study investigates the inhibitory properties of HMBA on mild steel corrosion in HCl solution through weight loss measurements, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques. The experiments spanned over various time periods, including 1, 5, 10, 24, and 48 h. The results reveal that HMBA exhibits exceptional inhibition efficiency (IE), with an impressive 94.7% inhibition rate. This outstanding performance underscores its potential as a corrosion inhibitor for mild steel in aggressive HCl environments. To elucidate the adsorption behavior of HMBA on the mild steel surface, Langmuir isotherm modeling was employed, demonstrating a strong correlation between the experimental data and the Langmuir adsorption isotherm model. Furthermore, the study employs density functional theory (DFT) to gain insight into the mechanism of HMBA inhibition. DFT calculations suggest that both physisorption and chemisorption mechanisms are involved in the interaction between HMBA and the mild steel surface. The calculated Gibbs free energy of adsorption () is found to be approximately , indicating a spontaneous and energetically favorable adsorption process. In conclusion, HMBA emerges as a highly effective corrosion inhibitor for mild steel in HCl solution, offering impressive IE over various time intervals. The combination of experimental techniques, such as WL, EIS, and PDP, along with computational insights from DFT calculations, provides an understanding of the inhibitory properties of HMBA. These findings hold great promise for the development of environmentally friendly corrosion inhibitors in industrial applications.

Sodium Methoxide Catalyzed Preparation of Nitrogen Compounds from Palm Oil Methyl Esters as Corrosion Inhibitor

This research was conducted to study preparation of nitrogen compounds by reacting palm oil derived methyl esters and diethanolamine using sodium methoxide as a catalyst. The chemical composition of the product was analyzed using the gas chromatography-mass spectrometry (GC-MS) method. The product was then applied as a corrosion inhibitor for mild steel in CO2 saturated 3% NaCl solution. Experimental results indicate that the reaction product contains six nitrogen compounds with a relative percentage of 63.7%, and the rest 36.7% are a mixture of unreacted diethanolamine and unreacted methyl esters. The results of the corrosion experiments show that the product obtained exhibited appreciably high performance as reflected by a percentage of protection (%P) of 96.85%. The performance of the product as a corrosion inhibitor is also supported by the SEM image of the mild steel sample, which shows that the surface of the sample is well protected. The results of this work demonstrate that nitrogen compounds obtained have promising potential as corrosion inhibitors, particularly to prevent corrosion by CO2 gas.

Applicability of some new pyrimidine derivatives for the corrosion inhibition of mild steel in the acidic environment

The current work targets to discover the potential of two pyrimidine derivatives, ethyl 4-[4-(dimethylamino)phenyl]-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate (ESP) and 4-[4-(dimethylamino)phenyl]-6-methyl-N-phenyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxamide (DSP), for the protection of C1018 steel from acidic corrosion. Electrochemical tests like electrochemical impedance spectroscopy, linear polarization resistance, potentio-dynamic polarization, and electron frequency modulation were employed for assessing the anticorrosive capability of the synthesized ESP and DSP. Both ESP and DSP inhibitors exhibited great inhibition activity, and the inhibition effectiveness attained 88.6 % for ESP and 94.9 % for DSP at saturation concentration.EIS data for ESP and DSP exposes that inhibition efficacy enhances with an increase in the doses of the two inhibitors by creating a protective film. The finest explanation for the adsorption of the examined molecules on the Fe surface was provided by the Langmuir model. The surface morphology was also evaluated by using SEM and EDX techniques. Computational studies like DFT and MC simulation methods were employed to determine the connection between anticorrosion performance and the inhibitor structure, which agrees with the experimental outcomes.

Extraction of flavonoids from Butterfly blue pea (Clitoria ternatea) flower as carbon steel corrosion inhibitor in CO2 environment: Experimental and theoretical approaches

The present study emphasizes the extraction of flavonoids from the Butterfly blue pea (Clitoria ternatea), a flower containing very strong antioxidant properties. The extracts were prepared using solvents with different polarity namely chloroform (CTCH), ethanol (CTET), ethyl acetate (CTEA) and water (CTW). The phytochemical studies for all extracts were evaluated to screen the phenolic content, flavonoid content, reducing power assay and tannin content as potential source of antioxidant properties of the flower. The crude aqueous extract (CTW) had the maximum phenolic content (106.79 ± 4.40 mg/GAE g) and the highest flavonoid content (85.05 ± 5.01 mg QE/g). All of the extracts were then characterized using complementary analyses, including FTIR, TGA, DSC, 1H and 13C NMR. CT extracts showed a substantial amount of phenols and flavonoids in comparison with standard quercetin. The performances of mild steel to prevent corrosion in 3.5 % NaCl medium doped with CT extracts (50, 100, 250, 500, 750, 1000 ppm) were ascertained by carrying out electrochemical measurements. It is apparent that CTW is superior in terms of corrosion inhibition of mild steel in NaCl medium under CO2 environment with respect to CTET extract (%IECTW = 89.91 % > %IECTET = 85.53 %). Adsorption of both inhibitors on the surface of MS obeyed Langmuir isotherm. Therefore, it can be inferred from the findings that CT extracts were adsorbed via both physical and chemical adsorption, hence showing excellent corrosion resistance behaviour, thus indicating its potential to be an alternative source of natural antioxidants potent CO2 corrosion inhibitor.

Experimental and computational chemistry investigation of the molecular structures of new synthetic quinazolinone derivatives as acid corrosion inhibitors for mild steel

Two new organic compounds, namely, 3-(2-(2-chloroethoxy)ethyl)-2-phenylquinazolin-4(3H)-one (QZ-H) and 3-(2-(2-chloroethoxy)ethyl)-2-(4-chlorophenyl)quinazolin-4(3H)-one (QZ-Cl) were synthesized based on quinazolinone derivatives, and their chemical structures were identified using non-instrumental analytical methods such as proton and carbon nuclear magnetic resonance (1H NMR and 13C NMR). After successfully synthesizing and spectrally characterization, they were tested for mild steel protection in 1.0 M HCl medium. In addition, their anticorrosion characters and molecular structure-activity relationship were evaluated using the classical electrochemical and theoretical methods, respectively. Experimental studies showed that these compounds are good corrosion inhibitors, where their inhibition efficiencies increase with their concentrations to reach a maximum of 87.75 % and 88.76 % at 10−3 M of QZ-H and QZ-Cl, respectively. It is also found that these products react as mixed-type inhibitors. In addition, the estimated activation parameters indicate that the dissolution process of mild steel is endothermic and the products act via physical adsorption on metallic surface according to the Langmuir isotherm. Finally, the theoretical studies using DFT calculations and MD simulations authorize the experimental results and the order of inhibition efficiency.

Inhibition potential of extract of leaves of Sodom apple in the corrosion of mild steel in 1.0 M H<sub>2</sub>SO<sub>4</sub>

Corrosion inhibition of mild steel in 1.0 M sulphuric acid by extract of leaves of Sodom apple has been studied using gravimetric and surface analysis. Varying concentrations (0.5, 1.0, 1.5 and 2.0 g/mL) of the inhibitor in 1.0 M H2SO4 were prepared from residue of an ethanolic extract of the sample and were used for the corrosion inhibition study. The extracts were previously confirmed by Fourier Transform Infrared Spectroscopy and screened for phytochemicals including tannins, saponins, and cardiac glycosides. The results for anticorrosion studies showed that the highest inhibition efficiency of the extract was 89.3% at 1.5 g/mL inhibitor concentration and a temperature of 323 K. Equally, the corrosion rate of the steel was observed to decrease with increase in the concentration of the extract. Scanning electron micrographs also indicated that the extract actually slows down the rate of corrosion of the steel. The study further suggests that the corrosion inhibition mechanism of the extract on steel in 1 M H2SO4 could be modelled using Freundlich isotherm and that the inhibition was by physisorption and formation of multilayers on the steel surface.