Corrosion Inhibition and Adsorption Behavior of Musa Basjoo Siebold Leaves Extract on Mild Steel in H3PO4 Solution: Experimental and Theoretical Studies

Musa basjoo Siebold leaves extract (MBSLE) was utilized as green corrosion inhibitor for mild steel in 1 M H3PO4 solution. The inhibition behavior was studied through electrochemical tests. The chemical structure of extract was investigated by FTIR and UV–Vis spectra. The element compositions in adsorption film on the surface of mild steel were analyzed by XPS technique. The corrosion morphology of mild steel was observed. The adsorption mechanism of typical components in extract were theoretically calculated by DFT and MD. The results showed that the inhibition efficiency of MBSLE on mild steel increased with extract concentration and MBSLE acted as a mixed corrosion inhibitor. MBSLE contained carbonyl, carboxyl, hydroxyl, heterocyclic ring, benzene ring and other polar groups, and successfully adsorbed on mild steel to form the protective film. DFT simulations proved that the active components possessed the synergistic adsorption ability to donate and receive electrons. MD calculations demonstrated the parallel adsorption of typical ingredients on steel surface, the presence of physical adsorption and the inhibition mechanism of geometric coverage effect. Irenolone in MBSLE with more aromatic rings and polar groups shows an excellent corrosion inhibition performance.