Study of Protic Ionic Liquids as Sustained Corrosion Inhibitors for Mild Steel in Saline Solution with Acidic pH and Temperature Variations

Electrochemical and computational insights into the utilization of 2, 2- dithio bisbenzothiazole as a sustainable corrosion inhibitor for mild steel in low pH medium

Experimental assessment and molecular-level exploration of the mechanism of action of Nettle (Urtica dioica L.) plant extract as an eco-friendly corrosion inhibitor for X38 mild steel in sulfuric acidic medium

Protic ionic liquids (PILs) have shown to be promising substances as corrosion inhibitors (CIs). In line with this, the aim of this study is to study the performance and propose the corrosion inhibition mechanism of N‐methyl‐2‐hydroxyethylamine (M‐2HEAOL) and bis‐2‐hidroxyethylamine (B‐HEAOL) oleate, for mild steel, in a neutral chloride solution. Electrochemical characterization was conducted under static and hydrodynamic conditions, and it was revealed that M‐2HEAOL and B‐HEAOL worked as mixed‐type CIs with more interference on the anodic reaction. Inhibition efficiency depended on the concentration reaching 97% of inhibition efficiency in 5 mmol/L concentration. Scanning electron microscopy, optical interferometry, Raman spectroscopy, and Fourier‐transform infrared spectroscopy are used to elicit the chemical composition of the surface film and corrosion morphology of steel in the presence of CIs, the adsorption processes of which involved physical and chemical adsorption between metal and different parts of ionic liquids. The results allowed the proposition of a corrosion inhibition mechanism.

Corrosion is a pervasive issue affecting metallic materials, with significant economic losses and safety risks in various industries. Mild steel, extensively used in construction and infrastructure, faces corrosion challenges, needing continuous research to effectively tackle them. Natural compounds, because of their eco-friendliness and corrosion inhibition potential, are attracting increasing interest for corrosion control. Lawsonia inermis (LI), or henna, a plant native to North Africa and South Asia, has bioactive compounds exhibiting corrosion inhibitive properties. This study comprehensively explores Lawsonia inermis’s effectiveness as a corrosion inhibitor for mild steel, filling a gap in the existing research. Various concentrations of Lawsonia inermis extract were tested in acidic solutions to evaluate corrosion inhibition. Experimental results indicate a significant reduction in the corrosion rate with increasing inhibitor concentration. Langmuir adsorption isothermal analyses reveal the adsorption mechanism as being an interplay between physisorption and weak chemisorption. Electrochemical measurements demonstrate Lawsonia inermis’s capability to alter both cathodic and anodic reactions, leading to improved corrosion resistance. Scanning electron microscopy reveals a more even surface morphology in the presence of the Lawsonia inermis, indicating corrosion inhibition. Gas chromatography–mass spectrometry (GC-MS) analyses identified organic compounds in Lawsonia inermis extract responsible for corrosion inhibition. Overall, Lawsonia inermis emerges as a promising corrosion inhibitor for mild steel, offering excellent inhibition efficiencies. This study sheds light on its adsorption behaviour and provides insights into its mechanism of action. These findings underscore Lawsonia inermis’s potential as a green corrosion inhibitor, paving the way for its practical application in industrial corrosion protection strategies.

The industry's principal objective is to comprehend the optimal application of each metal alloy in terms of corrosion resistance. A key focus lies in exploring alternative approaches to address this corrosive process in a manner that is both sustainable and economically feasible. The major strategy to mitigate this contest involves the utilization of inhibitors. However, it is imperative to note that certain inhibitors pose environmental risks. This study explores the effect of the addition of protic ionic liquids (PILs) on the corrosion of carbon steel (A36) in a saline solution (3.5 wt% NaCl), considering variations in pH and temperature. It focuses on understanding the effects of pH and temperature on the PILs' ability to protect the steel surface. Notably, changes in pH do not affect the protective capacity of the inhibitors. Efficiency values exceeding 72% were achieved under both acidic conditions tested. The study reveals two scenarios: At 40 °C, the PILs effectively protect the steel, with an efficiency of approximately 74% at concentrations of 500 and 1000 ppm. However, at 60 °C, efficiency decreases notably, reaching a maximum of 51% at a concentration of 500 ppm. Afterward, to evaluate the protective effectiveness of these compounds, gravimetric and electrochemical impedance spectroscopy (EIS) serve as the main methods, accompanied by optical and atomic force microscopy (AFM) for evaluating the surface. In electrochemical tests, PILs 1 and 2 exhibit superior efficiency, with film formation, while PILs 3 to 6 demonstrate comparatively lower values.

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

Tilia Leafs extract activity as a green corrosion inhibitor (environmental friendly) for mild steel in 1M HCl has been tested using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). The obtained results show that Tilia Leafs extract is an excellent corrosion inhibitor. The inhibition efficiency increases with increasing the temperature from 25 to 45°C, reaching a maximum value of 79% at the highest concentration of 300 ppm at the temperature of 45°C. Polarization measurements demonstrate that the Tilia Leafs extract acts as a mixed type inhibitor. Nyquist plot illustrates that on increasing Tilia Leafs extract concentration, the charge transfer increases and the double layer capacitance decreases. The adsorption of Tilia Leafs extract on mild steel obeys Temkin adsorption isotherm.

The effectiveness of 5-acetyl-4-(3-methoxyphenyl)-6-methyl-1-phenyl-3,4-dihydropyrimidin-2(1H)-one as a corrosion inhibitor for mild steel in acidic conditions was investigated herein through the experimental and theoretical approach. Experimental results demonstrated that this compound acts as a reliable corrosion inhibitor (η %) for mild steel in acidic environments, with its inhibition efficiency increasing as the inhibitor concentration rises. Adsorption behavior on the mild steel surface followed Langmuir and Temkin adsorption isotherms. Electrochemical polarization tests indicated that the compound exhibited a mixed corrosion type, and impedance spectroscopy revealed an increase in charge transfer resistance with higher inhibitor concentrations. Examination of the mild steel surface using SEM and Atomic Force Microscopy (AFM) confirmed the formation of a protective film. Wettability characteristics were assessed using the contact angle method. Frontier molecular orbital analysis revealed the HOMO and LUMO values for both the neutral and protonated forms of the compound. At 289 °C, the interaction energy for adsorption was found to be approximately −146.3006 kJ/mol for the neutral system and −135.8122 kJ/mol for the protonated system, while at 318 °C, the corresponding values were −140.6106 kJ/mol and −147.6022 kJ/mol. These findings collectively suggest the potential industrial utility of the investigated inhibitor as an effective corrosion inhibitor.

In situ corrosion inhibition in acid cleaning processes by using green inhibitors is at the forefront of corrosion chemistry. Plant extracts, especially alkaloids, are known to be good corrosion inhibitors against mild steel corrosion. In this research, alkaloids extracted from Acacia catechu have been used as green corrosion inhibitors for mild steel corrosion in a 1 M H2SO4 solution. Qualitative chemical tests and FTIR measurements have been performed to confirm the alkaloids in the extract. The inhibition efficiency of the extract has been studied by using weight-loss and potentiodynamic polarization methods. A weight-loss measurement has been adopted for the study of inhibitor’s concentration effect, with a variation employed to measure the inhibition efficiency for time and temperature. The weight-loss measurement revealed a maximum efficiency of 93.96% after 3 h at 28 °C for a 1000 ppm alkaloid solution. The 1000 ppm inhibitor is effective up to a temperature of 48 °C, with 84.39% efficiency. The electrochemical measurement results revealed that the alkaloids act as a mixed type of inhibitor. Inhibition efficiencies of 98.91% and 98.54% in the 1000 ppm inhibitor concentration solution for the as-immersed and immersed conditions, respectively, have been achieved. The adsorption isotherm has indicated the physical adsorption of alkaloids. Further, the spontaneous and endothermic adsorption processes have been indicated by the thermodynamic parameters. The results show that alkaloids extracted from the bark of Acacia catechu can be a promising green inhibitors for mild steel corrosion.

A detailed atomic level computational and electrochemical exploration of the Juglans regia green fruit shell extract as a sustainable and highly efficient green corrosion inhibitor for mild steel in 3.5 wt% NaCl solution

<p>The production of green corrosion inhibitors from locally sourced organic wastes makes environmental friendly corrosion inhibitor available. The aim and objective of this is to produce corrosion inhibitor from local Musa Sapientum Peels with a perspective of establishing the kinetics of the adsorption of Musa Sapientum Peels extract on mild steel bar in 2.0M sulphuric  acid. Musa Sapientum Peels extract produced was used as a corrosion inhibitor on mild steel bar in concentrated sulphuric acid using weight loss method. The results showed that the concentration of corrosion inhibitor is directly proportional to inhibitor efficiency and surface coverage but inversely proportional to weight loss of mild steel bar. Langmuir Isotherm, Freundlich Isotherm and Kinetic – Thermodynamic model predicted the kinetics of the ethanol extract of Musa Sapientum peels used as a corrosion inhibitor of mild steel bar while Linear isotherm did not. Among the three isotherms that predicted the results, Freundlich has the best correlation than Langmuir and Kinetic – Thermodynamic model based on the value of the goodness fit.</p>

The corrosion inhibition behaviour of four selected Mannich bases compounds,namely 3-((N-methyl,N-phenyl)-methyl)2,4-Acetylacetone(MPMAA),3-((N-phenyl)-methyl) 2,4-Acetylacetone (PMAA),3-((N, N-diethyl)-methyl) 2, 4-Acetylacetone(DMAA) and 3-((N, N-methyl)-methyl) 2, 4-Acetylacetone (MMAA) as corrosion inhibitors for mild steel in 1M HCl solutions. Tafel polarization methods were performed to determine the corrosion parameters and inhibition efficiencies. Experimental results showed that PMAA is an excellent inhibitor for mild steel corrosion in 1M HCl solutions; showing a maximum efficiency 92.3% at concentration of 40mg/L. Polarization studies showed that the Mannich bases compounds can be regarded as mixed-type inhibitors and the inhibition efficiency of the four inhibitors followed the order PMAA > MPMAA > DMAA > MMAA. Then scanning electron microscope (SEM)techniques were also employed to examine the mechanism of corrosion inhibition property.

This study explores the corrosion inhibition performance of ofloxacin for mild steel in 0.1 M and 0.5 M hydrochloric acid solutions and was investigated using the gravimetric (weight loss) method at 298 K. Different concentrations of ofloxacin (0.1–0.5 g/L) were employed to evaluate its effect on corrosion rate, inhibition efficiency and surface coverage. The results revealed that ofloxacin significantly reduced the corrosion rate of mild steel in both acidic media. Maximum inhibition efficiencies of 78.86% in 0.5 M HCl and 70.86% in 0.1 M HCl were achieved at 0.5 g/L inhibitor concentration. The inhibition efficiency increased with increasing inhibitor concentration, indicating adsorption-controlled inhibition. Adsorption of ofloxacin on the mild steel surface followed the Langmuir adsorption isotherm, suggesting monolayer adsorption. The study confirms that ofloxacin is an effective corrosion inhibitor for mild steel in hydrochloric acid environments.

This study presents an evaluation of the corrosion inhibition behavior of three protic ionic liquids (PILs), 2-hydroxy diethanolamine formate (PIL A: 2-HDEAF), 2-hydroxy diethanolamine propionate (PIL B: 2-HDEAP), and 2-hydroxy diethanolamine pentanoate (PIL C: 2-HDEAPe), on A36 carbon steel in a chloride electrolyte (3.5 wt % NaCl). The emphasis was converged on elucidating interfacial adsorption, film formation, and surface chemistry that reinforce inhibitor efficacy. A complementary set of electrochemical and surface techniques, including weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), optical microscopy, field-emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM), was employed to evaluate the electrochemical response and characterize the inhibitor-modified steel surfaces. X-ray diffraction (XRD) was used to perform an identification of the main phases of corrosion products and adsorbed films. The adsorption behavior was quantitatively evaluated using several adsorption isotherm models, including Langmuir, Temkin, and Freundlich. Among them, the Frumkin isotherm provided the best description of the experimental data, yielding an average standard free energy of adsorption (ΔG°ad) of -20.89 kJ mol-1, which is indicative of predominantly physical adsorption at the steel/electrolyte interface. Among the PILs studied, PIL A exhibited the highest inhibition efficiency (>75%) and promoted the formation of a dense, protective interfacial film, whereas PILs B and C showed progressively lower performance. Inhibition efficiency correlated positively with inhibitor concentration and followed the trend PIL A > PIL B > PIL C. Surface morphologies demonstrated significant mitigation of chloride damage in the presence of PILs, consistent with electrochemical results. XRD analysis revealed the stabilization of surface films (iron oxides and oxyhydroxides), including goethite, which are indicative of altered interfacial reactions in the inhibited systems. These results accentuate the importance of interfacial adsorption evaluation and film formation mechanisms in governing corrosion inhibition performance, highlighting the potential of tailored PILs for surface protection in chloride-containing media.

Corrosion inhibition and adsorption studies of Ammonium oxalate for mild steel by computational and experimental techniques: A sustainable approach