Green Corrosion Inhibition Properties of Croton Persimilis Extract on Mild Steel in Acid Media

Abstract

Croton persimilis is a medicinal plant composed of a variety of biologically active components. In the present work, screening of phytochemicals present in ethanolic Croton persimilis leaf extract (CP extract) has been conducted using Mayer’s test, Salkowski’s test, etc. UV–Visible spectral analysis has been performed to demonstrate the metal-binding ability of CP extract with various metal salts. Further, the anticorrosion effect of CP extract in 1 M HCl and 0.5 M H2SO4 for mild steel has been explored by physicochemical and electrochemical analysis. The weight loss process delineates that the added concentration of CP extract causes an increase in its corrosion inhibition power. Electrochemical studies such as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques are also in exact agreement with the weight loss process and show the mixed-type inhibition character of CP extract. The electrochemical noise spectrum also strongly supports the corrosion inhibition property of CP extract, and the magnitude of the noise signal decreases, corresponding to the increase in CP extract concentration. Neocrotocembraneic acid, stigmasterol, and β-sitosterol are major components of Croton persimilis leaves. The first two have been subjected to quantum mechanical studies, and the data observed are in line with all other techniques. Adsorption studies of CP extract follow Langmuir isotherm. Surface morphological studies using a scanning electron microscope strengthen the presence of a protective barrier on mild steel surface in both acid media. Statistical analysis by response surface method to determine the synchronized effect of temperature and CP extract concentration on inhibition efficiency empowers the results obtained in weight loss measurements. All the corrosion monitoring techniques have revealed that CP extract possesses excellent inhibition efficiency and acts as a green corrosion inhibitor for mild steel in aggressive media.