Corrosion inhibition of mild steel in 1M HCl using environmentally benign Thevetia peruviana flower extracts

The corrosion inhibition of Thevetia peruviana (Kaner) flower extract (TPFE) is evaluated for mild steel in 1M HCl solution using electrochemical, surface and computational demonstrations. Results showed that TPFE acted as a potential corrosion inhibitor and shows the highest inhibition efficiency of 91.24% at 200 mg/L concentration. Electrochemical studies suggest that TPFE acted as a mixed- and interface-type of corrosion inhibitor. The TPFE inhibits metallic corrosion through an adsorption mechanism that follows Temkin adsorption isotherm model. Adsorption mechanism of corrosion inhibition was further supported using AFM, SEM-EDX, FT-IR and UV-visible surface studies. Furthermore, the anticorrosive mechanism of major phytochemicals of the TPFE was studied using computational techniques: Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations. Results showed that TPFE interacts with donor-acceptor interactions and its phytochemicals acquire the flat or horizontal orientations over the metallic surface.

Automated summary

The study demonstrated that Thevetia peruviana (Kaner) flower extract (TPFE) can effectively inhibit corrosion of mild steel in 1M HCl solution, with the highest inhibition efficiency reaching 91.24%. The corrosion inhibition mechanism of TPFE primarily involves adsorption, and its major phytochemicals tend to orient themselves horizontally over the metallic surface.