The inhibition performance of quinoa seed on corrosion behavior of carbon steel in the HCl solution; theoretical and experimental evaluations

Theoretical and experimental studies on the electrochemical behavior of steel in HCl solution in the presence of two bio-inhibitor mixtures

In this new study, the inhibitory effectiveness of two bio-inhibitor mixtures has been studied on the corrosion characteristics of carbon steel in an HCl environment. The inhibitors were derived from a plant seed (quinoa seed-QS) and an insect extract (Oestrus ovis larvae-OOL). The total inhibitor concentration was a variable factor even the ratio of bio-inhibitor concentration was a fixed parameter. The electrochemical behavior of steel substrate was investigated through the Tafel polarization and electrochemical impedance spectroscopy measurements. Fourier transform infrared spectroscopy and field emission scanning electron microscopy were performed to identify bonds and analyze the morphology of the corroded surface of the steel. Additionally, molecular dynamics (MD) simulation and quantum calculations were applied to investigate the inhibitory influence of utilized bio-inhibitors. The experimental results indicated that the corrosion resistance decreased to 85 % when the optimum total concentration of the bio-inhibitor was 1 g L-1. The Langmuir model was used to illustrate the adsorption mechanism on the steel surface when physical adsorption occurred. Quantum chemical calculations revealed that the QS-inhibitor adsorbed more effectively onto the metal surface than the OOLE-inhibitor, due in part to a lower energy gap and higher HOMO energy. MD simulation and Monte Carlo calculations further confirmed that the QS-inhibitor was adsorbed on the Fe (110) surface with higher adsorption energy than the OOLE-inhibitor.

A new study on the corrosion inhibition mechanism of green walnut husk extract as an agricultural waste for steel protection in HCl solution

In this study, green walnut husk (GWH) extract was explored as a cost-effective (waste-agricultural) and eco-friendly inhibitor to increase the corrosion resistance of carbon steel in a 1 M HCl solution. Electrochemical impedance spectroscopy, weight change, and potentiodynamic polarization (PDP) tests were utilized to examine the electrochemical behavior of steel substrates with and without the inhibitor. Atomic force microscopy (AFM), field emission scanning microscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were performed to analyze corroded surface structures with and without the inhibitor. This inhibitor was found to be 27-82 % efficient in increasing the corrosion resistance of the steel substrates. When the temperature of the solution was increased from 303 to 323 K, the retardation coefficient decreased due to the physical adsorption of GWH molecules on the surface. The results indicated that GWH acted as a mixed inhibitor, and its adsorption on the surface followed the Langmuir model. AFM measurements showed that the roughness of corroded surfaces decreased by approximately 22 % when the GWH concentration was at its optimum level of 400 ppm. Thermodynamic studies displayed a decrease in the corrosion reaction's activation energy of about 25 %. FTIR and XRD patterns of corroded surfaces represented that hydrated iron chloride was the dominant corrosion product. Furthermore, the results provided insight into the GWH adsorption mechanism.

Analysis of natural okra extracts as corrosion inhibitors for mild steel in acidic medium

Plant extracts have been shown to effectively inhibit metal corrosion. Using the Box-Behnken design, gravimetric, and electrochemical techniques, analyses were designed to investigate the anti-corrosion potential of okra in a 1M HCl medium. The inhibition performances derived from the various methods were in good agreement, demonstrating that physio-chemisorption was effective and adhered to the Langmuir isotherm model. The efficiency of okra mucilage extract was 96% at a much lower concentration compared to 91.2% and 88.4% for the unsieved extract and gelly-okra filtrate, respectively. FTIR results showed the presence of several functional groups in the okra mucilage extract that are associated with adsorption, and TGA analysis revealed that the extract has high thermal stability. FESEM analysis also supported evidence of adsorption. It was determined that corrosion inhibition by okra mucilage extract was primarily influenced by temperature, followed by extract concentration, with immersion time having the least effect. From the model optimization, it was observed that okra mucilage extract at 200 ppm, 60°C, and 24 h gave an inhibition efficiency of 89.98% and high desirability. These results demonstrate the high capacity of natural okra as an efficient biodegradable corrosion inhibitor.

Quantitative and qualitative analyses of grafted okra for corrosion inhibition of mild steel in acidic medium

Introduction: Natural plant polymers demonstrate effective corrosion inhibition abilities, because of their numerous binding sites and excellent adsorption abilities. Methodology: In this study, the Box-Behnken method, gravimetric and electrochemical analyses were used to design and investigate the corrosion inhibition potential of a modified graft polymer of okra for mild steel in a 1M HCl medium. The influence of inhibitor concentration, temperature, and time were also investigated. Qualitatively, the Fourier Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA), and Field emission scanning electron microscopy (FESEM) were used to characterize the extracts and evaluate the metal's surface morphology. Results and discussion: The quantitative analyses showed that the modified natural polymer's inhibition efficiency (IE) increased with concentration and reached 73.5% at 800 ppm, with a mixed-type mode of inhibition. From the response surface methodology, it was revealed that temperature influences the IE more than concentration and immersion time. The optimized IE using the desirability function showed the possibility of attaining 88.2% inhibition with inhibitor concentration at 142.3 ppm, temperature at 60.4°C, and an immersion time of 22.4 h. The new functional groups in the hybrid polymer revealed by FTIR analysis shows that grafting improved the inhibitor's adsorption abilities. TGA analysis confirmed the extract's high thermal stability, which highlights the inhibitor's strong adsorption and efficiency for high temperatures. FESEM analysis indicated evidence of inhibitor adsorption onto the metal surface. Conclusion: These findings suggest that the grafting of okra with acrylamide enhances its inhibition properties and contributes to its functionality as a cost-effective plant-based alternative inhibitor against corrosion for mild steel facilities.

The corrosion inhibition of carbon steel in 1 M HCl solution by Oestrus ovis larvae extract as a new bio-inhibitor

Since, nowadays, utilizing the eco-friendly and economic corrosion inhibitors in various industries is a challenge, in this research, the corrosion behavior of carbon steel in the HCl solution by the addition of the extract of Oestrus ovis larvae as a novel bio-inhibitor has been evaluated. The electrochemical tests plus the gravimetric investigations were performed to study the corrosion property of steel substrates in various concentrations of bio-inhibitor (0.25-3 g/L). Different methods such as grazing incidence X-ray diffraction, field emission scanning electron microscopy (FESEM), and atomic force spectroscopy (AFM), were utilized to detect the chemical composition and morphology of corroded surfaces. Results of the Tafel polarization showed that the inhibition efficiency was about 57-86% with the highest value at the inhibitor concentration of 1 g/L. Electrochemical impedance spectroscopy results indicated that with the specified concentration of bio-inhibitor the electrochemical properties of samples changed based on the suggested electrical circuit. Results showed that the adsorption isotherm of the inhibitor was the Langmuir model with the cathodic-anodic performance. Both FESEM and AFM images demonstrated that the intensity of deterioration and the roughness of corroded surfaces reduced significantly at the optimum concentration of inhibitor (1 g/L). The inhibition mechanism was proposed based on experimental results.

Role of Organic and Eco-Friendly Inhibitors on the Corrosion Mitigation of Steel in Acidic Environments-A State-of-Art Review

Steel has versatile application in chemical, structure and construction industries owing to its mechanical properties. However, it is susceptible to corrosion in acid environments. Thus, it requires to protect the steel from corrosion. Different types of corrosion resistance steel, coatings and inhibitors are developed to mitigate the corrosion, but, inhibitor is the best remedies to control the corrosion of steel in acid condition. Moreover, organic and green inhibitors used in acid condition for descaling, acid pickling, pipelines, boiler tubes and oil-wells. Organic inhibitors reduce the dissolution of steel in acid but, it is hazardous, expensive and needs expertise to synthesize the inhibitor. Therefore, there is utmost required to study and compile the latest research about the eco-friendly corrosion inhibitors, which showed more than 90% corrosion inhibition efficiency. In the present study, I have reviewed the state-of-arts, and compile the latest development in organic and eco-friendly corrosion inhibitor used in acid environment as well as suggested about the future scope and role of green inhibitor for sustainable society, which is economical, less hazardous and readily available from the natural sources.