Increasing Inhibitor Concentration Research Articles

Macroscopic behaviors and chemical reaction mechanism for the inhibition of NH4H2PO4 powder in hybrid methane/coal dust deflagrations

In this research, the inhibition effect and microscopic mechanism of NH4H2PO4 on the macroscopic deflagration characteristics of methane (9.5 vol%) mixed with three coal samples were studied. Experimental results show that the higher the concentration of added NH4H2PO4, the more pronounced the inhibition effect on the deflagration of three coal samples mixed with methane. When the mass concentration of NH4H2PO4 reached 90%, the deflagration pressures of anthracite/methane hybrids, coking coal/methane hybrids, and long-flame coal/methane hybrids decreased by 50.80%, 45.59%, and 39.06%, respectively. The time for the flame front to reach the height of 300 mm extended by 39 ms, 30 ms, and 63 ms, respectively. In addition, the microscopic reaction mechanism of NH4H2PO4 inhibiting the methane/coal dust deflagration was revealed using a reaction kinetics model. We found that phosphorus-containing substances mainly absorbed explosive active free radicals through cyclic reactions HOPO2 = PO2 and HOPO = PO2. Through ROP analysis, we found that with an increase in inhibitor concentration, the HOPO radical, which had a better scavenging effect on oxidizer free radicals, was gradually replaced by HOPO2, resulting in a saturation effect. Sensitivity analysis showed that the inhibitory effect of NH4H2PO4 mainly depended on phosphorous substances and free radicals HOPO, HOPO2, and PO2.

Carbon steel behavior towards Cucumeropsis mannii shell extract as an ecofriendly green corrosion inhibitor in chloride medium

This study advanced on previous studies by investigating the hardness and tensile strength of carbon steel under different loads after determining the corrosion rate at different temperature, immersion time and corrosion inhibitor concentration in a chloride medium using Cucumeropsis mannii shell extract (CMSE) as an eco-friendly green corrosion inhibitor. The inhibition efficiency was evaluated by weight loss, electrochemical impedance spectroscopy and potentiodynamic polarization techniques. Adsorption behavior and material characterization were investigated. The result revealed maximum inhibition efficiency of 92.2% and 91.2% could be attained by EIS and PDP techniques respectively. The corrosion rate decreases as the inhibitor's concentration increases and vice versa for temperature and immersion time. The Young modulus and hardness of carbon steel decreased at higher load under corrosion attack in the absence of CMSE. The green corrosion inhibitor exhibited a mixed-type with a spontaneous physisorption behavior on carbon steel surface. Material characterization revealed presence of active functional groups in the extract with formation of uniform and pitting corrosion on carbon steel surface. In conclusion, Cucumeropsis mannii shell extract behaved excellently as corrosion inhibitor for carbon steel in chloride solution.

Investigation of two triazine derivatives as potential eco-friendly corrosion inhibitors for copper in artificial seawater

The inhibiting action of 6-N,N-bis(6-methylheptyl)amine-1,3,5-triazine-2,4-dithiolmono-sodium, (iso-DON) and 6-dibutylamino-1,3,5-triazine-2,4-dithiol monosodium (DBN) on the corrosion of copper in artificial seawater (3.5 wt% NaCl solution) has been investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) methods and scanning electron microscopy (SEM) techniques. The results from weight loss and electrochemical measurements consistently identify that both iso-DON and DBN exhibit good performance as inhibitor for copper corrosion in 3.5 wt% NaCl solution and the inhibition efficiency increases with the increase in inhibitor concentration. Potentiodynamic polarization measurements reveal that the studied triazine dithiol derivatives act as mix-type inhibitors, and the maximum value of the inhibition efficiency was obtained (93 % for iso-DON and 95 % for DBN) when the inhibitor concentration reaches 1.5 mM. EIS imply that the corrosion of copper in NaCl solution is influenced by charge transfer. The adsorption of iso-DON and DBN molecules on copper surface was found to obey the Langmuir adsorption isotherm. Parameters for adsorption indicate a strong interaction between inhibitor molecules and copper surface, and the negative values of ΔGθ reveal the spontaneous adsorption of iso-DON and DBN on copper surface.

Evaluation of corrosion characteristics of mild steel in the acidic environment using Cocoyam and Almond leaves extracts as inhibitors

The inhibition characteristics of Almond and Cocoyam leaves extracts on mild steel immersed in 1 M H2SO4 at immersion times of 24 h to 144 h have been investigated experimentally. The effects of various concentrations of the extracts on the corrosion rate and inhibition efficiency were also explored. The average corrosion rates (in mm yr-1) and inhibition efficiencies (in %) were determined at each extract concentration and immersion time. Results show that both extracts demonstrated excellent inhibition characteristics for mild steel in H2SO4 media as the corrosion rate of the mild steel decreased from 43.0096 mm yr-1 to 4.7019 mm yr-1 and 4.9528 mm yr-1 after adding 8 g/L of Cocoyam and Almond leaves extracts respectively. This can be linked with the adsorption of molecules of oxidative phytochemical constituents of the extracts on the mild steel surfaces which shielded the mild steel surfaces from further attack by the acid. Within the time range of the study, the inhibition efficiency of both Cocoyam and Almond leaves extracts increased with an increase in inhibitor concentration with maximum inhibition efficiencies of 70.15% and 56.67% recorded by Almond and Cocoyam leaves extracts respectively at concentrations of 8 g/L. Conclusively, Almond leaves extracts are better mild steel corrosion inhibitors than cocoyam leaves extracts, due to the lower pH value of Cocoyam leaf extract.

Adsorption characteristics of Luffa Cylindrica leaf extract as a corrosion inhibitor of copper in alkaline environment

Copper corrosion inhibition by Luffa cylinderica leaf extract has been studied in 0.01M Sodium hydroxide solution (NaOH) using electrochemical measurement. Inhibition efficiency increase as the inhibitor concentration increases and decrease with temperature while corrosion rate decreases with concentration and increase with rise in temperature. At the optimum concentration (1000mg/L), the highest inhibition efficiency of plant extract was found to be 72.1846% at 303K and 68.1242% at 313K , and the corrosion rate (10-5) was 1.2679 at 303K and 1.4059 at 313K. However, increase in temperature decreased the inhibition efficiency at the temperature range studied. The phenomenon of physical adsorption has been proposed from the activation energy values (3.8933 to 7.9793 kJ mol-1) with Luffa cylinderica leave extract and the heat of adsorption, Qads ranges from (-26.4619 to - 15.3085 kJmol-1) for concentration of inhibitor studied. These values are negative and suggestive of adsorption on metal surface. The surface morphology and the composition of copper metal were also examined using SEM and XRD analysis respectively. The data obtained from this study fits well into the Langmuir adsorption isotherm.

Investigating the Inhibitory Properties of Cupressus sempervirens Extract against Copper Corrosion in 0.5 M H2SO4: Combining Quantum (Density Functional Theory Calculation-Monte Carlo Simulation) and Electrochemical-Surface Studies.

The study investigates the potential of Cupressus sempervirens (EO) as a sustainable and eco-friendly inhibitor of copper corrosion in a 0.5 M sulfuric acid medium. The electrochemical impedance spectroscopy analysis shows that the effectiveness of corrosion inhibition rises with increasing inhibitor concentrations, reaching 94% with the application of 2 g/L of EO, and potentiodynamic polarization (PDP) studies reveal that EO functions as a mixed-type corrosion inhibitor. In addition, the Langmuir adsorption isotherm is an effective descriptor of its adsorption. Scanning electron microscopy/energy-dispersive X-ray spectroscopy, atomic force microscopy surface examination, and contact angle measurement indicate that EO may form a barrier layer on the metal surface. Density functional theory calculations, Monte Carlo simulation models, and the radial distribution function were also used to provide a more detailed understanding of the corrosion protection mechanism. Overall, the findings suggest that Cupressus sempervirens (EO) has the potential to serve as an effective and sustainable corrosion inhibitor for copper in a sulfuric acid medium, contributing to the development of green corrosion inhibitors for environmentally friendly industrial processes.

Anti-corrosive and anti-microbial activity of MTMI on CRCA metal

The present study was intended to demonstrate the synthesis, and characterization of 1-(3-methoxyphenyl)-N-(4H-1,2,4-triazol-4-yl)methan-imine(MTMI) as an inhibitor for the corrosion on CRCA in 1 M HCl. In addition to this, molecular docking, and biological activity was carried out. MTMI formation was confirmed by FTIR and NMR spectroscopic studies. The corrosion inhibition effect was studied by weight loss, potentiodynamic polarization (PDP) measurements, and electrochemical impedance spectroscopy (EIS) techniques. The conditions for optimum inhibition efficiency were established by varying the concentration of the inhibitor and temperature by weight loss method. Kinetic and thermodynamic parameters were calculated and discussed. Results were fitted into various adsorption isotherm models. The adsorption of MTMI on CRCA was confirmed by scanning electron microscopy (SEM). Adsorption obeyed the Langmuir isotherm model and followed physical adsorption. Increasing inhibitor concentration led to a significant reduction in the corrosion rate of mild steel, with an inhibitor efficiency value above 93%. A molecular docking study showed the binding capacity of the protein endo-polygalacturonase (1HG8) and the activity of polygalacturonase enzyme on MTMI was measured.

Surface and interfacial properties of poly(methyldiallylammonium chloride): Effect of hydrophobic pendant and synergism (KI) on corrosion of C1018CS in 15% HCl

BackgroundIn the current investigation, a dicationic surfactant made of poly(methyldiallylammonium chloride) (PMDAAC) was tested for its ability to suppress corrosion of C1018 carbon steel (C1018 CS) in a 15% HCl (acidizing) solution. MethodsWeight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), linear polarization resistance (LPR), scanning electron spectroscopy (SEM), energy dispersive X-ray (EDX), atomic force microscope (AFM), and density functional theory (DFT). Significant findingsWeight loss tests show that PMDAAC has no significant inhibitory potential for the C1018CS/15% HCl system, as seen by its inhibition efficiency (IE) of 76.57% at 50 ppm concentration. However, adding 5 mM KI significantly increases the% IE of PMDAAC from 76.57% to 95.26% at the same concentration. A similar trend in the boost of% IE of PMDAAC from 85.33% to 99.28% and 83.28% to 98.42% was observed through PDP and EIS studies, respectively. PDP study showed that the current density (icorr) values kept decreasing with increasing PMDAAC concentration. PMDAAC behaves as a mixed- and interface-type inhibitor, being able to retard the progress of both anodic and cathodic reactions. EIS analysis showed that the values of charge transfer resistance (Rct) kept increasing with increasing inhibitor concentration. The adsorption isotherm study suggests that PMDAAC becomes effective by adsorbing on the C1018 CS surface, and its adsorption follows the Langmuir isotherm. A high value of 6.37 × 105 L mol-1 corresponds to the equilibrium constant for the adsorption process (Kads), indicating very strong adsorption of PMDAAC onto C1018 CS. PMDAAC was found to chemisorb onto the metal surface, as confirmed by the Gibbs free energy of adsorption (ΔGads∘) found to be – 43.76 kJ mol−1. The adsorption of PMDAAC on the C1018CS surface was confirmed by SEM and EDX studies. The improvement in surface morphology and alteration in elemental alignment in the presence of PMDAAC demonstrate the adsorption mode of corrosion mitigation. Lastly, the interaction of PMDAAC and its constituting components were described using the DFT method.

Investigation Effect of 4-Aminophenol as a Corrosion Inhibitor for Mild Steel in Sulfuric Acid Medium

A high number of organic materials have been studied as inhibitors for corrosion in different conditions. In this paper, the effect of organic chemical (4-Aminophenol) as an inhibitor for mild steel metal corrosion was investigated in presence of sulfuric acid at different temperatures. The study was carried out using three known methods in testing corrosion process, methods of weight loss, thermometric, and polarization. The obtained results showed that when the inhibitor concentration increases, the corrosion rate decreases, and hence, the inhibition efficiency increases. Moreover, when the surface coverage at a temperature of 313 °C with organic inhibitor increases, the corrosion rate decreases as noticed in the weight loss method. For the thermometer method, the inhibitor was examined by temperature. The inhibition efficiency increases, as well as in the anodic and cathodic polarization method, where it is observed that the anodic and cathodic curves are present to measure the corrosion current and corrosion potential. As the higher the concentration of the inhibitor, the lower the current and the corrosion voltage. The reason for the effectiveness of this inhibitor is the presence of amine and phenol organic molecules in its composition, which can form a film on the metal surface and prevent corrosion from taking place.

N,N-Dimethylaniline as corrosion inhibitor for zinc in sulphuric acid medium

The inhibitive effect of N, N-Dimethylaniline (DMA) as corrosion inhibitor for zinc in 0.1, 0.3 and 0.5 M H2SO4 solutions has been investigated by using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results obtained reveal that inhibition efficiency (I.E.) increases with increase in concentration of inhibitors but decreases with increase in temperature. As inhibitor concentration increases corrosion rate decreases. The rate constant ‘k’ decreases while half-life ‘t½’ increases with the increase in concentration of inhibitor. DMA showed maximum I. E. of 93.51 % at 60 mM in 0.5 M H2SO4 acid at 301 K. The inhibition effect is discussed in view of DMA molecules adsorbed on the metal surface and it obeys Langmuir adsorption isotherm. Polarization curve indicates that inhibitor act as mixed type for zinc corrosion in sulphuric acid solutions.

Using electrochemical testing and modeling to assess the efficiency of a water-soluble inhibitor on the corrosion of 6061Al-15 % (v) SiC (p) composite

Abstract The corrosion behaviour of 6061Al-15 % (v) SiC (P) composite was investigated in a 0.5 M HCl medium using electrochemical techniques. A water-soluble inhibitor, N-(1-morpholinobenzyl) semicarbazide (NMSc), was synthesised to test its corrosion inhibition activity on 6061Al-15 % (v) SiC (P) composite. The inhibitor showed cathodic-type behaviour and 95.42 % inhibition efficiency at 2.56 mM concentration and 303 K temperature. The thermodynamic results revealed the inhibitor’s physisorption, which followed Langmuir’s isotherm model. A drastic reduction in corrosion current density in the inhibited medium indicates that the inhibitor effectively controls the deterioration of the composite in the HCl medium. A significant rise in polarisation resistance on increasing inhibitor concentration offers greater resistance for the charge transfer process, ensuring better control over the composite corrosion. The surface analysis by scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirms the inhibitor film formation on the composite. The quantum chemical theoretical calculations supported the electrochemical results.

Corrosion resistance of Aluminium steel in 1N Sodium Hydroxide solution by an aqueous extract of Thespesia populnea plant leaves

Corrosion resistance effect of aluminium steel in 1N sodium hydroxide by an aqueous extract of Thespesia populnea plant leaves has been investigated by mass loss method. It is observed that as the concentration of the inhibitor increases, the inhibition efficiency increases. The mechanistic aspects of corrosion resistance have been studied by potentiodynamic polarization technique and electrochemical impedance spectroscopy. A maximum inhibition efficiency of 78.70% is achieved by this inhibitor system. Potentiodynamic polarization technique reveals that the inhibitor system functions as a mixed type of inhibitor, controlling anodic and cathodic reactions. It is noted that in the presence of inhibitor, linear polarization resistance value increases and corrosion current decreases. Electrochemical impedance studies reveal that a protective film is formed on the Al steel surface, since in the presence of inhibitor system, the charge transfer resistance value increases and double layer capacitance value decreases. This is due to adsorption of the molecules of the active ingredients of the extract on the Al steel surface. The inhibition efficiency increases due to adsorption of hetero atoms present in TP plant leaves extract on the Al steel surface. The maximum inhibition efficiency and the lower corrosion rate are obtained at high concentration 1200 ppm for TP plant leaves extract. By further increase in inhibitor concentration above 1200 ppm, the inhibition efficiency and corrosion rate almost remained constant. So, the 1200 ppm concentration is fixed as the maximum inhibition for the investigative aqueous extract of plant leaves as corrosion inhibitor. This concentration corresponds to the attainment of a saturation value in surface coverage of Al steel. The protective film formed over the Al steel surface has been characterized by Fourier Transform infra-red spectroscopy. The surface morphology of the protective film of carbon steel immersed in sodium hydroxide in the absence and presence of inhibitor has been studied by Scanning electron microscopy. The outcome of the study can be used in pickling industry wherein sodium hydroxide is used to remove the rust on the Al steel surface.

Study of Corrosion Inhibitory Effects of Alcoholic Extracts of <i>Tinospora Cordifolia</i> on Metal Tin in Acidic Media HCl with and without Additive (KCl)

The corrosion inhibitory efficiency of Tinospora Cordifolia stem and leaf extract in different concentrations of HCl acid (0.5, 1, 2, and 3N) was examined using weight loss and thermometric methods in the absence and presence of an additive (KCl). According to the findings of this investigation, inhibition efficiency (ɳ%) rises with increasing inhibitor concentration as well as acid strength, and additional improvement in inhibition efficiency was found with the addition of additives (KCl) owing to a synergistic effect. According to the findings, stem extract is a better corrosion inhibitor than leaf extract. The maximum inhibition efficiency was observed for stem and leaf extracts (95.76 and 92.47 %) at their maximum concentrations (0.8 %) in the absence of an additive in the maximum strength of HCl acid (3N), while it was observed at 98.58 and 95.29 % in the presence of additive (3N KCl) of maximum strength.

Insights into the uses of two azine decorated d10-MOFs for corrosion inhibition application on mild steel surface in saline medium: Experimental as well as theoretical investigation

Recently, the use of metal–organic frameworks (MOFs) as an efficient corrosion inhibitor has been focused on due to their unique excellent properties such as being rich in π-electron system, chemical and thermal robustness and supramolecular task-specific functionality etc. The present work demonstrates the judicious synthesis of two d10-MOFs namely CI@Cd-MOF and CI@Zn-MOF utilizing organic struts like 4,4′-oxybisbenzoic acid (OBA) and (1E,2E)-1,2-bis(1-(pyridine-4-yl)ethylidene)hydrazine (BPD) and investigated as efficient inhibitor for mild steel corrosion in an adverse corrosive medium i.e. in 3.5 wt% saline medium. The applications of MOFs as heterogenous inhibitor for mild steel corrosion in saline medium have been assessed via potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) studies. The EIS analysis shows that the effectiveness of corrosion inhibition rises with increasing inhibitor concentrations, reaching 90.15 % with the application of 50 ppm of CI@Zn-MOF. PDP study reveals that both MOFs act as a mixed kind of inhibitor. Post-corrosion study of the mild steel surface has been characterised by Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) analysis and 3D-surface profilometer study demonstrating that the application of inhibitors results in a significant reduction of the corrosion process. The water contact angles on the steel surface increased from 49° to 104.2° and 108.1° due to the adsorption of inhibitors on the steel surface following the Langmuir adsorption isotherm model. Furthermore insightful explanations and correlations with density functional theory (DFT) have been provided for the experimentally observed corrosion inhibition performance as well as adsorption capability. Molecular dynamics (MD) simulation has been conducted to mimic the interactions of the inhibitors with metal surface atoms and corrosive species in an actual corrosive medium. The high binding energy (1328.12 kJ/mol for CI@Zn-MOF) provides evidence that inhibitors are able to spontaneously adsorb on steel surfaces. Additionally, the pivotal role of non-covalent intermolecular interactions in a confined space has been assessed using non-covalent interaction based on the reduced density gradient (NCI-RDG) technique.

Iron-ligand complex, an efficient inhibitor of steel corrosion in hydrochloric acid media

The inhibitor effect of FeSO4(Hdpz) complex prepared from iron (II) sulfate7-hydrate and 1-Hydroxymethyl-3,5-dimethylpyrazole on corrosion of mild steel in 1 M hydrochloric acid (HCl) at 308 K was investigated using measurements of weight loss and electrochemical techniques (impedance spectroscopy and polarization curves). Inhibition efficiency depends on the concentration of complex [FeSO4 (Hdpz)] and its inhibition efficiency increases with an increase in inhibitor concentration to 98% for 10−3 M. Polarization curves show that the complex FeSO4(Hdpz) basically functions as a mixed inhibitor. Measurements of electrochemical impedance spectroscopy (EIS) indicate an increase in transfer resistance at the concentration of the inhibitor. In the temperature range of 308 to 348 K, the temperature effect on the corrosion behavior of steel in 1 M HCl without and with the inhibitor at 10−3 M was studied and the corresponding activation energy was calculated. Adsorption of FeSO4(Hdpz) complex on the mild steel surface in 1 M HCl follows the Langmuir isotherm model. The quantum approach and monte Carlo simulation was confirmed the reactivity of the studied compound towards the corrosion process.

Corrosion inhibition of Schiff base and their metal complexes with [Mn (II), Co (II) and Zn (II)]: Experimental and quantum chemical studies

The synthesis, characterization, and examination of anti-corrosion performance of 2-furaldehyde semicarbazone Schiff base (FSC) complexes of cobalt (II), zinc (II), and manganese (II) on XC38 carbon steel immersed in 1 M HCl solution are performed using experimental investigations and quantum chemical simulation approaches. The theoretical approach used were DFT calculations and MC simulation. The inhibition effect was also studied by electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP). Electrochemical testing results show that these chemical compounds are particularly powerful inhibitors, which FSC-Mn provides a considerable inhibition of 91.48%at 500 ppm. The results also demonstrate that the inhibition effect of the four inhibitors increased with increasing inhibitor concentration, revealing that these compounds adsorb significantly to the steel surface. The scanning electron microscopy (SEM) analyses indicated that FSC and its complexes adsorbed onto the surface of XC38 carbon steel by forming a barrier between the inhibitors and the vacant d-orbital of iron. Quantum investigations were consistent with experimental findings on the four inhibitors’ capacity to prevent XC38 carbon steel from corroding in 1 M HCl, which were also proven effective as cathodic and anodic type inhibitors, displacing water molecules from mild steel, and producing heterogeneous coatings on the XC38 carbon steel surface to defend against corrosion.

Electrochemical, surface analysis, and theoretical investigation of 3-hydroxy-5-(phenylamino)-4-(p-tolyldiazenyl)thiophen-2-yl)(phenyl)methanone as a corrosion inhibitor for carbon steel in a molar hydrochloric acid solution

In this work, a comprehensive study for using (3-hydroxy-5-(phenylamino)-4-(p-tolyldiazenyl)thiophen-2-yl)(phenyl)methanone as a corrosion inhibitor for carbon steel in a 1.0 M HCl was performed. For this purpose, different types of electrochemical and surface analysis techniques as well as a computational simulations have been applied. The obtained experimental results showed that the investigated compound is a promising corrosion inhibitor for carbon steel in acidic environments. Adding a low inhibitor concentration of about 5 × 10−5 M at room temperature resulted in an inhibition efficiency of up to 93.25 %. The inhibition efficiency increases with increasing inhibitor concentration while decreasing with increasing temperature. This trend has been demonstrated and discussed precisely by potentiodynamic polarization (PDP) measurements. SEM and AFM were used to examine the surface morphology of the electrode before and after inhibition. The inhibitor adsorbs on the surface of the steel, acting as a barrier at the steel/HCl acid interface and thus blocking the steel electrode's surface. DFT calculations and MC simulations were used to demonstrate the adsorption process. The findings also revealed that it is a mixed-type inhibitor that follows Henry's adsorption isotherm. The experimental and theoretical studies agree remarkably well. The inhibition mechanism has also been discussed.

Evaluation of the corrosion inhibition of mild steel by newly synthesized imidazo[1,2-a]pyridine derivatives: experimental and theoretical investigation

In the pickling industry, corrosion can deteriorate the quality of equipment and supplies, causing financial losses and safety threats. Therefore, it has become crucial to develop novel corrosion inhibitors that are bioactive, efficient, affordable, medium-acid soluble, and ecologically safe to protect mild steel during industrial cleaning. In this work, three newly synthesized imidazo[1,2-a]pyridine derivatives were characterized by various spectroscopic techniques. The studied compounds were evaluated as corrosion inhibitors for mild steel in 1 M HCl medium using weight-loss, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. The imidazopyridine derivatives showed excellent anticorrosion performance, their inhibitory efficiencies increased with the increase of inhibitors concentration and evolved in the following order: Imd2 (98.1%) >Imd1 (96.5%) >Imd3 (95.3%). This order was justified by the presence of two chlorine atoms in the ortho position of the Imd2 structure. The three Imd derivatives obeyed to the Langmuir isotherm, this explained the formation of an organic monolayer on the steel surface indicated by the scanning electron microscope (SEM) and the atomic force microscope (AFM). In addition, density functional theory (DFT) and molecular dynamics (MD) simulations were performed to reveal the anticorrosion mechanism. The present study illustrates at the microscopic level how mild steel resists corrosion and ensures the safety of pickling.

Investigation of 3-(1,3-oxazol-5-yl)aniline as a highly efficient corrosion inhibitor for mild steel in 1 M HCl solution

Abstract Mild steel corrosion in acidic environments presents a significant challenge with detrimental consequences for both industrial infrastructure and the environment. Effective corrosion control measures are crucial to prolonging the lifespan of equipment. Inhibition techniques have proven to be an efficient method for protecting mild steel from corrosion, particularly in acidic conditions. This study investigates the efficacy of 3-(1,3-oxazol-5-yl)aniline (3-OYA) as a corrosion inhibitor for mild steel in a hydrochloric acid (HCl) solution. Traditional weight-loss tests, as well as electrochemical techniques, such as potentiodynamic polarization and electrochemical impedance spectroscopy, were employed to evaluate the corrosion inhibition performance. The results reveal that 3-OYA, at a concentration of 0.05 mM, exhibits an outstanding protection efficacy of 93.5%. This remarkable performance can be attributed to the formation of a protective adsorption layer on the mild steel surface, effectively inhibiting the corrosion rate and enhancing inhibitory efficacy. The inhibition efficiency was found to increase with increasing inhibitor concentration, while it decreased with rising temperature. Langmuir adsorption isotherm analysis confirmed the high adsorption–inhibition activity of 3-OYA. The $\Delta {G}_{ads}^o$ value indicated the occurrence of both physical and chemical adsorption mechanisms on the mild steel surface. Furthermore, density functional theory (DFT) calculations were utilized to determine the quantum chemical parameters and establish a correlation between the inhibition activity and the molecular structure. The consistency between the experimental and theoretical analyses reinforces the robustness of our findings.

Investigation of some new triazole derivatives for inhibiting the acid corrosion of C1018 carbon steel: Correlation of electrochemical studies with quantum chemical calculations

Iron and alloys of iron are commonly used in industries for various purposes. Despite their toughness, they are prone to corrosion. A common way to protect metallic components from corrosion is the use of pyridine inhibitors. Hence, two new triazole derivatives, ethyl{[5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetate (EPT) and 2-({[5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}methyl)-1H-benzimidazole (PTB) have been synthesised and the formation of compounds were confirmed by spectral data. The inhibition efficacy of both the inhibitors on C1018 metal in 1 M HCl were examined by electrochemical techniques. The results proved the anticorrosive ability of EPT and PTB with inhibition efficiency of 92% and 94%, respectively. Meanwhile, current density decreased from 1330 µA/cm2 to 106 µA/cm2 for EPT and 79.5 µA/cm2 for PTB with an increase in inhibitor concentration. Further, both of the triazole derivatives behaved as mixed type inhibitors through the Langmuir adsorption mechanism. Surface morphological analysis gave further proof for the higher adsorbing ability of these triazole derivatives on the metallic surface. The above experimental investigations were validated by performing quantum chemical calculations. The results of theoretical methods indicated the effectiveness of EPT and PTB for protecting the metal from acid corrosion.