Corrosion Inhibition Effect and Adsorption Activities of methanolic myrrh extract for Cu in 2 M HNO3

Eco-Friendly Methanolic Myrrh Extract Corrosion Inhibitor for Aluminum in 1 M HCl

Aluminum corrosion was inhibited by myrrh extract when it was placed in a solution of 1 M HCl. Several procedures were used for these tests, including weight loss WL, potential dynamic polarization PL, and electrochemical impedance EIS in addition to theoretical calculations like density functional theory (DFT), Fukui functions, and Monte Carlo simulation. Fourier transform infrared spectroscopy was used to analyze the compositional surface of Al. Scanning electron microscopy was used to determine the shape of the Al surface. The inhibition rate of Al corrosion in HCl with varying myrrh extract contents at 25-45 °C was studied. An analysis of the PL curves indicates that myrrh extract is an inhibitor of mixed type. Upon increasing the concentration of myrrh, the inhibition efficiency increased. Moreover, rising temperatures decrease inhibition efficiency. It was discovered that the inhibition process follows the Langmuir isotherm, demonstrating that a monolayer has formed on the surface of aluminum. Theoretical and practical studies proved the validity of the conclusions.

Aizoon extract as an eco-friendly corrosion inhibitor for stainless steel 430 in HCl solution

Aizoon extract is used as an eco-friendly anti-corrosive material for stainless steel 430 (SS430) in a 2 M hydrochloric acid solution. Many strategies were utilized to estimate the mitigation efficacy such as mass reduction (MR), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP). The inhibition percentage (%I) increases by increasing the concentration of Aizoon and reaches 95.8% at 300 ppm and 298 K, while it lowers by raising the temperature, reaching 85.6% at 318 K. Tafel curves demonstrated that Aizoon extract is a mixed type inhibitor with an excellent ability to inhibit the cathodic reaction. Adsorption of the Aizoon extract on an SS430 surface is regulated by the Langmuir adsorption model. The value is is -20.9 kJ mol^-1 at 298 K indicating that the adsorption is of mixed type affecting both cathodic and anodic reactions. Thermodynamic factors for adsorption and activation processes were estimated and discussed. The adsorption of Aizoon extract on the SS430 surface was tested utilizing Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) techniques. The Nyquist curves confirmed that Aizoon extract prohibits the disintegration of SS430 in an acid medium without changing the dissolution reaction mechanism. The theoretical calculations showed that Aizoon extract is considered as an excellent corrosion inhibitor. The experimental data were supported by theoretical evaluations.

Plant Extracts as Green Corrosion Inhibitors for Different Metal Surfaces and Corrosive Media: A Review

Natural extracts have been widely used to protect metal materials from corrosion. The efficiency of these extracts as corrosion inhibitors is commonly evaluated through electrochemical tests, which include techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurement. The inhibition efficiency of different extract concentrations is a valuable indicator to obtain a clear outlook to choose an extract for a particular purpose. A complementary vision of the effectiveness of green extracts to inhibit the corrosion of metals is obtained by means of surface characterizations; atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy analysis are experimental techniques widely used for this purpose. Moreover, theoretical studies are usually addressed to elucidate the nature of the corrosion inhibitor—metal surface interactions. In addition, calculations have been employed to predict how other organic substances behave on metal surfaces and to provide experimental work with fresh proposals. This work reports a broad overview of the current state of the art research on the study of new extracts as corrosion inhibitors on metal surfaces in corrosive media. Most constituents obtained from plant extracts are adsorbed on the metal, following the Langmuir adsorption model. Electron-rich regions and heteroatoms have been found to be responsible for chemisorption on the metal surface, whereas physisorption is due to the polar regions of the inhibitor molecules. The plant extracts compiled in this work obtained corrosion inhibition efficiencies above 60%, most of them around 80–90%. The effect of concentration, extraction solvent, temperature, and immersion time were studied as well. Additional studies regarding plant extracts as corrosion inhibitors on metals are needed to produce solutions for industrial purposes.