Mild Steel In Acidic Environment Research Articles

Green-synthetized β-amino-α-carbethoxy ethyl acrylates as corrosion inhibitors for mild steel in acid media: Experimental performance evaluation and atomic/molecular-level modeling

Two β-amino acrylate derivatives were synthesized through a solvent- and heating-free mechanochemical procedure. Those substances were tested as corrosion inhibitors for mild steel in acidic environment (1 mol/L HCl). Weight Loss Study demonstrated that both molecules mitigate corrosion with 85 and 90 % efficiencies. Electrochemical experiments proved that the corrosion mechanism is charge transfer and that the presence of EOAB and DBMM at any tested concentration in the electrolyte significantly increases the polarization resistance and lowers the corrosion density current. This phenomenon is due to the adsorption of the molecules on the mild steel surface, leading to the formation of a protection film that prevents the corrosion reaction, as suggested by Atomic Force Microscopy topographic images. The self-consistent-charge density-functional tight-binding method (SCC-DFTB) revealed that their adsorption strength on the iron surface followed well the corrosion inhibition performance. Both inhibitor molecules formed covalent bonds with iron atoms as evidenced from stable adsorption geometries and projected density of states. Quantum chemical parameters seem to fail in predicting the experimental performance. Outcomes from the present study confirmed the fact that an additional functional group would lead to an increased inhibition performance is not a granted correlation.

Exploring chromone derivatives as environmentally friendly corrosion inhibitors for mild steel in acidic environments: A comprehensive experimental and DFT study

Exploring chromone derivatives as environmentally friendly corrosion inhibitors for mild steel in acidic environments: A comprehensive experimental and DFT study

KINETIC AND THERMODYNAMIC ASSESSMENT OF THE POTENCY OF IRVINGIA GABONENSIS PLANT EXTRACT AS AN ECO-FRIENDLY INHIBITOR FOR MILD STEEL IN AN ACIDIC ENVIRONMENT

The kinetic and thermodynamic efficacy of Irvinga Gabonensis plant extract as an effective eco-friendly inhibitor for mild steel in acidic environment were studied using gravimetric measurement (GM) at varied temperature of 298,308, and 318 K, as well as

Combined electrochemical, DFT/MD-simulation and hybrid machine learning based on ANN-ANFIS models for prediction of doxorubicin drug as corrosion inhibitor for mild steel in 0.5 M H2SO4 solution

In this work, Doxorubicin drug was used as mild steel corrosion inhibitor in 0.5 M H2SO4 solution. Herein, standard techniques like gravimetric, electrochemical measurement, density functional theory via DFT/ molecular dynamic simulation (MDS), Scanning electron microscopic (SEM), were used for proper evaluation of Doxorubicin drug as anticorrosive agent. According to the experimental findings, Doxorubicin drug significantly inhibits mild steel corrosion, and its effectiveness increases with an increase in the drug concentration. Maximum inhibition efficiency at 100 ppm was 93.3 %, 91.3 % and 96.8 % for electrochemical impedance (EIS), polarization test (PDP) and gravimetric techniques respectively. The electrochemical study indicates that Doxorubicin is a mixed-type inhibitor. Close scrutiny of the corroded and inhibited metals evidenced that Doxorubicin drug produced a better and more uniform coating on the surface of mild steel. The molecular structure of the drug and its contribution to the inhibition mechanism was further understood using simulations based on density functional theory (DFT) and molecular dynamics simulation (MDS). In addition, artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were used to predict and model the interactive effects affecting the response. Also, statistical parameters like coefficient of determination (R2), root mean square error (RMSE), mean absolute percentage error (MAPE), and mean absolute deviation (MAD) were used to assess the models' performance. The results demonstrate that the FCM-clustered ANFIS model with 15 clusters perform better than ANN model with RMSE, MAD, MAPE, and R2values of 0.978, 0.642, 4.823, and 0.9925 at the testing phase, and 0.6435, 0.4248, 2.8151, and 0.9998 at the training phase respectively. The best prediction was made using complete FCM-ANFIS model, which had accuracy of 98.4 %. Hence, a robust system prediction can be achieved via ANN and ANFIS algorithms to predict corrosion inhibition of mild steel in acidic environment using drug based corrosion inhibitors.

Evaluating the efficacy of synthesized quinoline derivatives as Corrosion inhibitors for mild steel in acidic environments: An analysis using electrochemical, computational, and surface techniques

Two quinoline derivatives such as 5-(ethoxymethyl)-2-methylquinoline-8-ol,and 5-((2-aminoethoxy)methyl)-2-methylquinoline-8-ol symbolized by (Q) and (QN), respectively were studied in HCl (1.0 M) by experimental, and computational approaches to inhibit the corroding of the mild steel (M-S). Q and QN were found to delay the corrosion of the mild steel in the research environment. Q and QN displayed mixed inhibiting properties, decreasing the rate of anodic and cathodic corrosion reactions. The Q and QN molecules developed a film on the surface of the material in HCl (1.0 M), which is consistent with the impedance measurements. Coverage data of the surface adsorption has fitted into the Langmuir adsorption isotherm. SEM/EDS, AFM, contact angle, and XPS analysis also indicated that the adsorbent film of Q and QN protects the steel from ions of acid. In addition, a molecular dynamics simulation was performed to optimize the inhibitor molecule equilibrium configurations at the Fe surface. From the experimental results, the sequence of the effectiveness of the studied inhibitors was validated through theoretical calculations.

Investigation of the corrosion inhibition performance of snail slime on the exposed surface of mild steel in acidic environment

Corrosion of metals is a major issue in various industries and the use of organic materials, especially plant extracts, as alternatives to toxic chemicals in corrosion inhibitors is gaining attention. However, the potential of animal products as corrosion inhibitors has not been fully explored. This study investigates the corrosion inhibiting potential of snail slime (SS) for mild steel in 0.5 M H2SO4 solution using Gravimetric and electrochemical methods, including open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used for material characterization. The results indicate that snail slime has a high inhibition efficiency of up to 92.75%, with inhibition efficiency decreasing as temperature and immersion time increase but it increased with higher inhibitor concentrations. Adsorption studies showed that snail slime exhibited strong adherence to the Langmuir and Temkin adsorption isotherms, indicating spontaneous adsorption on mild steel. The inhibition mechanism shows typical physical adsorption and follows first-order kinetics. While the EIS analysis indicated a charge transfer-controlled corrosion process with the highest inhibition efficiency of 81.74%, the PDP analysis revealed that snail slime acted as a mixed-type inhibitor with the highest inhibition efficiency of 81.98%. FTIR reveals the functional groups responsible for the inhibition exhibited by snail slime inhibitors, including CH, OH, CO-O, CCl, and NH. SEM shows that the inhibition of corrosion is due to the formation of an insoluble stable protective film on the sample surface by an adsorption process. These findings suggest that snail slime has significant potential as an eco-friendly alternative to synthetic corrosion inhibitors in industrial applications.

The effect of functional groups on the inhibitory efficacy of newly synthesized Imidazopyridines compounds against the corrosion of mild steel in acidic environments: Electrochemical, thermodynamic, surface and computational investigations (Part B)

The primary objective of this research paper was to investigate the inhibitory effects of two new derivatives of Imidazopyridines, namely: (E)-N-(7-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1-(3-nitrophenyl)methanimine (N-Imid) and (E)-2‑methoxy-4-(((7-methyl-2 phenylimidazo[1,2-a]pyridin-3-yl)imino)methyl)phenol (MH-Imid), on mild steel (MS) in 1 M hydrochloric acid at 308 K. The study also aimed to compare the protection capacities of these compounds. Additionally, the impact of (-OH & OCH3–) and (-NO2) groups on the inhibition efficiency was analyzed. The inhibition performance was measured using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and weight loss (WL) methods at 308 K, and confirmed by Scanning Electron Microscopy (SEM),UV–visible, and computational modeling, The study results showed that the both inhibitors displayed potent inhibition capacities, and their effectiveness grew notably with rising concentration and diminishing temperatures. Among the two compounds investigated, MH-Imid is the best with an inhibition efficiency over 96%. The substitution of functional groups was found to influence the inhibition efficiency. The electrochemical tests findings were consistent. The outcomes indicated that both inhibitors exhibited cathodic/anodic behavior (mixed type). SEM analysis was used to assess the surface morphology and showed the presence of a protective layer on the MS surface, The two studied inhibitors were adsorbed on the MS surface by the Langmuir adsorption model. Analysis of the inhibited and uninhibited solution using UV-visible spectroscopy showed evidence of a complex between Fe and two imidazopyridine molecules forming in 1 M HCl. The computational modeling matches experimental data well and demonstrates that the inhibition efficiency ranking (MH-Imid > N-Imid) holds consistently.

N-doped and N, Si-doped carbon dots for enhanced corrosion inhibition of mild steel in acidic environment

N-doped and N, Si-doped carbon dots for enhanced corrosion inhibition of mild steel in acidic environment

Inhibitory action of Spondias mombin leaves extracts on corrosion of mild steel in 1M HCl

Acid corrosion of steel and its associated financial and material costs are serious challenges to the chemical industry, and protecting these alloys through the use of effective corrosion inhibitors is imperative. In this study, the corrosion inhibition of mild steel in 1M HCl media using water and ethanol extracts of Spondias mombin leaves was investigated via weight loss technique, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The influence of temperature on inhibitor behaviour was also studied. Both extracts inhibited corrosion of mild steel via adsorption, following the Langmuir and Freundlich isotherms. The inhibition efficiency (IE) increased as extracts concentration was increased. After 24 and 72 hours exposure in the acid solution at 25 ℃, 500 ppm of extracts delivered maximum efficiency of (94.44 % and 76.52% for ethanol) and (51.52 % and 58,97 % for water). However, increasing temperature to 40 ℃ and 60 ℃ (after 24 hours) significantly boosted the efficiency of water extract (favoring inhibition via combined physical and chemical adsorption) but depreciated the performance of ethanol extract. The extracts provide good protection to mild steel in acidic environment and are therefore recommended as green alternatives to existing toxic ones.

ODHI: A promising isatin-based corrosion inhibitor for mild steel in hydrochloric acid

The study aimed to investigate the corrosion behavior of mild steel in acidic environments and to evaluate the effectiveness of an ecofriendly inhibitor named 2-oxo-3-((2,4-dimethoxybenzylidene)hydrazono)indolin (ODHI) derived from Isatin. The researchers employed various techniques such as weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy to carry out the experiment in both uninhibited and inhibited 1 M HCl solution at temperatures ranging from 303 to 333 K. The findings revealed that the inhibition efficacy increased with the concentration of ODHI, reaching 94.3% at 0.5 mM in a 1 M HCl solution at 303 K. The results were supported by Density Functional Theory computations, which confirmed the ODHI's corrosion inhibition behavior for mild steel in acidic conditions. The inhibition effect was found to follow the Langmuir isotherm model. Overall, the study demonstrates the potential of ODHI as an effective inhibitor for Mild Steel in acidic environments.

Evaluation of the Impact of Two Thiadiazole Derivatives on the Dissolution Behavior of Mild Steel in Acidic Environments.

In light of the variety of industrial uses and economic relevance of mild steel, corrosion resistance is a serious topic. Utilization of inhibitors serves as one of the most essential methods for corrosion control. Two thiadiazole compounds, namely, 2-amino-5-(4-bromobenzyl)-1,3,4-thiadiazole (a1) and 2-amino-5-(3-nitrophenyl)-1,3,4-thiadiazole (a2), were synthesized. The structure of the prepared compounds was verified by Fourier transform infrared spectroscopy (FTIR) and proton and carbon-13 nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR). In a 0.50 M H2SO4 solution, the effectiveness of two synthetic thiadiazole derivatives as mild steel corrosion inhibitors were investigated. In this evaluation, various electrochemical methodologies have been utilized, such as potentiodynamic polarization, open circuit potential (OCP), and electrochemical impedance spectroscopy (EIS). The results confirm the efficiency of the inhibition increases by raising concentrations of a1 and a2. The inhibitory behavior was explained by the notion that the adsorption of thiadiazole molecules, a1 and a2, on the surface of mild steel causes a blockage of charge and mass transfer, protecting the mild steel from offensive ions. Furthermore, the synthesized molecules a1 and a2 were analyzed using density functional theory (DFT).

Corrosion inhibition of mild steel in 0.5 M HCL by substituted 1,3,4-oxadiazole

Organic inhibitors are normally used to inhibit the corrosion of metals or alloys in an aqueous environment. The anti-corrosive property of 5((6-Methyl-2-oxo-2H-chromen-4yl)thiomethyl)-2((N-(3-methyl-quinoxalin-2(1H)one)yl) methyl)-1,3,4-oxadiazole (MOD) on mild steel (MS) was studied. Which acts as a novel corrosion inhibitor for MS in 0.5 M Hydrochloric acid (HCl) solution and corrosion behavior in the temperature range of 303–323 K, without and with the MOD inhibitor, was calculated using potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurements. The surface topography of mild steel with, and without MOD was investigated by Scanning electron microscopy (SEM) technique. The inhibitory efficiency increases with an increase in MOD (50 ppm) concentration and showed a maximum of 84.85% in 0.5 M HCl at 303 K. The variation in kinetic and thermodynamic properties of MOD on MS indicates chemisorption and its mixed kind of inhibition activity followed by the Langmuir adsorption isotherm. The experimental results are supported by Density functional theory (DFT) simulations, indicating a potential corrosion inhibition behaviour of MOD on MS in acidic environments. A suitable mechanism for the corrosion inhibition of mild steel was put forth. The corrosion inhibition mechanism of mild steel was discussed. Mild steel is a low-cost engineering material that can be regularly used for various applications such as construction, advertising, vehicles, furniture, fencing, and more in various conditions, including mild acidic ones with a little caution.

Kinetic and thermodynamic evaluation of azithromycin as a green corrosion inhibitor during acid cleaning process of mild steel using an experimental and theoretical approach

Data from experiments and molecular computation were used to evaluate azithromycin as a safe and innocuous corrosion retardant for mild steel in acidic environments. Hydrogen evolution experiments were conducted between 303 and 333 K with and without azithromycin in hydrochloric acid solution. SEM photos and the results of hydrogen evolution demonstrate that azithromycin suppresses steel corrosion in an acidic environment. The inhibition efficiency (IE%) of azithromycin increases with the rise in concentration and the drop in temperature. The maximum IE% (81.36%) was obtained at 800 mg/L of azithromycin at 303 K. The corrosion reaction rates could be described with a first-order rate law. The range of thermodynamic parameters obtained from 303 K to 333 K for entropy (−181.2 to −91.9 J/mol), enthalpy (18.6 to 50.1 kJ/mol), and activation energy (21.2 to 52.7 kJ/mol) indicate the corrosion is spontaneous and endothermic. The results of the experiment agreed with the Langmuir model for adsorption, and physisorption is postulated for the adsorption of azithromycin on mild steel based on the ΔG values (−12.0 to −2.8 kJ/mol) which were below −20 kJ/mol. According to computational details, oxygen hetero atoms with relatively very large Mulliken charges are the most susceptible active locations for adsorption of Azithromycin on the metal surface.

Electrochemical study on using aminated MIL–101(Cr) as corrosion inhibitor for mild steel in acidic environment

PurposeThe purpose of this paper is to confirm the importance of using metal–organic frameworks (MOFs) in the field of corrosion control due to their potential use as corrosion inhibitors.Design/methodology/approachNH2–MIL–101(Cr), an amine-functionalized chromium-based MOF [Cr(III)-MOF], was prepared by solvothermal technique. Thereafter, Cr-MOF was used as an anticorrosion additive for mild steel (MS) in 1 m HCl solution. This inhibition behavior was tested by electrochemical tests including electrochemical impedance spectroscopy and potentiodynamic polarization (PDP).FindingsIncreasing the added amount of Cr-MOF enhances its inhibition performance, which attained 96.40% at 30 ppm. The obtained data from PDP measurements describe Cr-MOF as a mixed-type inhibitor. Based on SEM/EDS and FTIR analysis, the adsorption of Cr-MOF on the surface of MS that prevents MS corrosion has been demonstrated. Furthermore, Langmuir model is the most adequate adsorption isotherm for the obtained experimental data.Originality/valueThis study revealed that NH2–MIL–101(Cr), an amine-functionalized chromium-based MOF (Cr(III)-MOF), is a potential corrosion inhibitor for MS in 1 m HCl solution.

Interactions and corrosion mitigation prospective of pyrazole derivative on mild steel in HCl environment

The effectiveness of 1H˗pyrazole˗3,5˗dicarboxylic acid 5˗benzyl ester 3˗phenyl ester (PCBPE) as a preventer for deterioration of IS 513 Gr. D steel in 1 M HCl medium is evaluated via weight loss, electrochemical impedance, and polarization techniques. Kinetic and thermodynamic parameters assessed the feasibility of the adsorption process at diverse temperatures. The inhibition action on mild steel has been enhanced with increasing PCBPE concentration. It is found from the polarization studies that PCBPE behaves as mixed type inhibitor in HCl medium. The adsorption process of PCBPE on mild steel surface from acid environment is favoured Langmuir adsorption isotherm. The shielding efficiency of PCBPE has been enhanced at elevated concentrations, and it has been diminished at amplified temperatures. The Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrum (EDS) were used to establish a surface characterization of metal specimens. A quantum chemical analysis of electron density distributions in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) demonstrated how the inhibitor undergoes adsorption on mild steel in 1 M HCl. All experimental findings substantiate the corrosion mitigation performance of PCBPE on mild steel in acidic environments.

Benzothiazolylhydrazine azomethine derivatives for efficient corrosion inhibition of mild steel in acidic environment: Integrated experimental and density functional theory cum molecular dynamics simulation approach

Synthesis of challenging corrosion inhibitors is of prime importance to inhibit hydrogen-induced and localised metallic corrosion occur in the corrosive acidic solution. In this regard, the present research has been focused on the development of functionalised Schiff bases, namely, 1-(benzo[d]thiazol-2-yl)-2-((furan-2-yl)methylene)hydrazine (BTFMH), 1-(benzo[d]thiazol-2-yl)-2-((thiophen-2-yl)methylene)hydrazine (BTTMH), 1-(benzo[d]thiazol-2-yl)-2-((5-methylthiophen-2-yl)methylene)hydrazine (BTMMH) with an aim of effectively curtailing the issues associated to hydrogen-induced cracking and subsequent inhibition of metallic corrosion taking place in the corrosive acidic solution. The corrosion inhibiting performances of the synthesized inhibitors have been assessed for mild steel surfaces exposed in 1 M HCl medium using gravimetric measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization study revealed that the synthesized inhibitor molecules retarded the cathodic hydrogen evolution reaction at cathodic site and subsequently minimized the oxidation of metals at anode; thereby, these Schiff bases acted as the mixed type inhibitors. The EIS study revealed that the corrosion inhibition phenomenon is being controlled through charge transfer processes. All of these three synthesized inhibitor molecules showed approximately 96–98 % corrosion inhibiting efficiency at exceedingly low concentration (0.5 mM). The inhibition efficacy obtained for these synthesized inhibitor molecules follows the order: BTMMH > BTTMH > BTFMH. The adsorption nature of these inhibitor molecules on mild steel surfaces have been revealed through surface morphology, topography and water contact angle studies. Thereafter, the insight of corrosion inhibition mechanism at atomic level have been explored by density functional theory (DFT). The optimized geometrical structure, electron density distribution of frontier molecular orbitals and their corresponding energy parameters obtained from DFT as well as Fukui indices analysis have been explored to unveil the plausible modes of adsorption or the reactive sites present within the inhibitor molecules which facilitate their interactions with surface atoms of metals. The non-covalent interaction based on reduced density gradient have been explored to study intrinsic feeble interaction acting with the molecules. Afterwards, molecular dynamics simulation has been employed to validate the spontaneity along with the nature of interaction at the metal inhibitor interface. Furthermore, the equilibrium adsorption configuration of the synthesized inhibitor molecules on the targeted metal surface atoms have been envisaged and the interfacial phenomenon has been explained.

Multidimensional analysis for corrosion inhibition by new pyrazoles on mild steel in acidic environment: Experimental and computational approach

Inhibition of mild steel (M.S) corrosion by some pyrazole-2-acetohydrazide derivatives, namely; ((E)-2-(3,5-dimethyl-1H-pyrazol-1-yl)-N'-(4-hydroxy-3-methoxybenzylidene)acetohydrazide (DHA) and (E)-2-(3,5-dimethyl-1H-pyrazol-1-yl)-N'-(furan-2-ylmethylene)acetohydrazide (DFA)) in 1 M HCl was studied using weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) measurements and Scanning Electron Microscopy (SEM) allowed M.S surface analysis. On the other hand, computational investigations (DFT and Monte-Carlo simulation (MCs), and Molecular dynamic simulations (MDs)) have been apprehended. The efficiency of inhibition increases as the concentration of inhibitor increases, and it also increases as the temperature increases. At a concentration of 10−3 M, the anti-corrosion performance of DHA was 97.6% and 85.9% for DFA, respectively, according to polarization measurements. PDP were used to obtain both anodic and cathodic inhibitions. The Langmuir isotherm was followed in the adsorption of DFA & DHA onto steel surfaces. Furthermore, when the inhibitor was present, SEM pictures exhibited better surface protection, which was matched with a molecular dynamic simulation that confirmed perfect surface alignment between the inhibitor and the M.S-surface. Experiments, DFT computations, MCs, and MDs are all in agreement.

Experimental, DFT and MC simulation analysis of Vicia Sativa weed aerial extract as sustainable and eco-benign corrosion inhibitor for mild steel in acidic environment

In the current investigation, the corrosion inhibition efficacy of a weed, Vicia Sativa has been investigated on the mild steel corrosion in 0.5 M HCl using weight-loss (WL) method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements (PDP) and scanning electron microscope (SEM) techniques, in addition to surface examination analysis. This investigation revealed Vicia Sativa extract (VSE) as a green and eco-benign corrosion inhibitor for mild steel in 0.5 M HCl corrosive solution demonstrated an inhibition efficiency (IE%) of 91.24% at 298K in presence of 1000 ppm of VSE. The results attained from EIS investigations indicated an enhancement in polarization resistance (Rp) from 55.78 Ω at 50ppm to 191.05 Ω at 1000ppm, affirming the inhibitive potential of the investigated inhibitor. Additionally, on increasing the concentration of VSE from 50ppm to 1000ppm, the values of icorr and corrosion rate (CR) decreased from 554.05 μA to 122 μA and 6.438mmy−1 to 1.4176mmy−1, demonstrating the excellent inhibition potential of VSE on the mild steel corrosion. Additionally, the cathode Tafel slope (βc) (from −142.76 to −153.24mV/dec) and anode Tafel slope (βa) (from 127.79 to 134.71mV/dec) values rarely altered when the inhibitor was introduced with increasing concentration from 50ppm to 1000ppm, showing that the process of hydrogen evolution stayed intact, revealing the inhibitor molecule adhesion on the metallic substrate which lessened the degree of active spots available for the reaction while sustaining the charge transfer process of hydrogen generation. Furthermore, integrated computational investigations, such as density functional theory (DFT) and Monte Carlo (MC) simulations confirms the potent inhibitory efficacy of VSE.

Multidimensional analysis for corrosion inhibition by Isoxsuprine on mild steel in acidic environment: Experimental and computational approach

This study investigates the impact of Isoxsuprine hydrochloride drug on mild steel corrosion in a 1.0 M HCl solution by employing weight loss, electrochemical methods, surface morphological techniques, and finally validated with theoretical studies like quantum calculation and MD simulation. Inhibitory efficacy of Isoxsuprine hydrochloride came out to be ∼ 97 % at 2000 ppm concentration. The analysis demonstrated the increase in the inhibition efficiency with the rising concentration of inhibitor and decreasing effectiveness with increased temperature. Thermodynamic parameters were also investigated by utilizing the data obtained from temperature. Potentiodynamic polarization validated that the Isoxsuprine hydrochloride retarded the cathodic as well as anodic reactions. During the adsorption process, the Isoxsuprine hydrochloride molecules followed the Langmuir adsorption isotherm. Theoretical calculations like quantum chemical calculation and molecular dynamics simulation also confirms excellent adsorption of Isoxsuprine hydrochloride on the metallic sample. The results from all of the different methods were consistent.

Performance evaluation of newly synthetized bi-pyrazole derivatives as corrosion inhibitors for mild steel in acid environment

Two new synthesized bi-pyrazole-carbohydrazides, namely 1,1′-(propane-1,3-diyl)bis (5-methyl-1H-pyrazole-3-carbohydrazide) (P2PZ) and 1,1′-(oxy bis (ethane -2,1-diyl)) bis (5-methyl-1H-pyrazole-3- Carbohydrazide) (O2PZ) were evaluated as corrosion inhibitors for mild steel (MS) in 1.0 M HCl media. Comparative study of inhibitory action of P2PZ and O2PZ was conducted first using mass loss and electrochemical measurements (potentiodynamic polarization curves, PPC, and electrochemical impedance spectroscopy, EIS) and it had shown that P2PZ outperforms O2PZ. The electrochemical studies showed a corrosion inhibition efficiency of 95% and 84% at 308 K and 10−3 mol/L of P2PZ and O2PZ, respectively. Their efficiency augmented with augmentation of concentration and decreased with augmentation of temperature. Electrochemical impedance spectroscopy showed that the corrosion inhibition followed a charge transfer process. Polarization curves suggested that the P2PZ and O2PZ acted as mixed-type inhibitors and followed the Langmuir adsorption isotherm. The free energy of adsorption (ΔGads) values, which lie within the range of -39.94 to -37.36 KJ mol−1, confirmed a physicochemical adsorption process. Scanning electron microscope (SEM) images indicated the formation of a protective layer on the surface of the metal in the presence of both inhibitors. Density Functional Theory (DFT) and molecular dynamics (MD) simulation have been introduced to carry out a theoretical investigation of the inhibitors’ reactivity and interaction with the iron surface, respectively. The comparative study based on experimental and theoretical results showed that the trend of inhibition potentials of tested inhibitors depends on their electron-donating/accepting abilities. The trend of reactivity of molecules P2PZ and O2PZ matched well with experimental results.