Neolamarckia cadamba alkaloids as eco-friendly corrosion inhibitors for mild steel in 1 M HCl media

The inhibition effect of Neolamarckia cadamba crude extract (bark, leaves) and pure alkaloid (3β-isodihydrocadambine) were investigated for mild steel corrosion in 1 M HCl medium. Potentiodynamic polarization, electrochemical impedance, scanning electron microscopy, FTIR spectroscopy and molecular modelling were employed for this study. Results showed that crude extracts and 3β-isodihydrocadambine reduced the corrosion rate significantly at all concentrations. Polarization measurements indicated that these green inhibitors acted through mixed type inhibition. SEM studies evidenced the formation of a protective film over metal surface while FTIR, supported by molecular modelling proved that this shielding effect was caused by alkaloids, particularly 3β-isodihydrocadambine.

► Neolamarckia cadamba extracts were first time examined as corrosion inhibitors.
► Cadambine alkaloid (3-β-isodihydrocadambine) was found to be the active ingredient.
► Inhibition mechanism supported by FTIR spectra and molecular modeling studies.