Adsorption isotherm and molecular modeling of phytoconstituents from Dillenia suffruticosa leaves for corrosion inhibition of mild steel in 1.0 M hydrochloric acid solution

Abstract

Plant extracts as green corrosion inhibitors have gained significant attention in minimizing metallic corrosion due to the presence of heteroatoms and polar groups found in extract molecules. The present work focused on the novel implementation of Dillenia suffruticosa leaves extract (DSLE) as a green corrosion inhibitor for corrosion protection of mild steel in 1 M hydrochloric (HCl) acid. Gravimetric characterizations and adsorption isotherm modeling (Langmuir, Temkin, El-Awady Sips, and Freundlich) showed that DSLE is an excellent corrosion inhibitor with inhibitive performance that increases with increasing extract concentration. Potentiodynamic polarization (PDP) showed that DSLE behaved as a mixed-type corrosion inhibitor. Given that one limitation of using plant extracts is its solubility in polar electrolytes, Monte Carlo (MC) simulations and density-functional theory (DFT) calculations were carried out to investigate the surface adsorption properties between polar and non-polar compounds found in DSLE. The results obtained showed that polar phytocompounds (saponins) were primary agents for corrosion inhibition. Our findings highlight the potential of using polar phytocompounds from Dillenia suffruticosa as green corrosion inhibitors for mild steel particularly in applications containing polar solvents and electrolytes.

Keywords

• Green corrosion inhibitor
• Plant extracts
• Polar phytoconstituents
• Adsorption isotherm models
• DFT calculations
• Potentiodynamic polarization