Corrosion inhibition of mild steel in seawater through green approach using leucaena leucocephala leaves extract

Abstract

Corrosion inhibition analysis of Leucaena leucocephala leaves extract (LLE) as an additive incorporated into a commercialized coating to protect mild steel when immersed in seawater has been successfully conducted. The procedures involve the utilization of multiple techniques including Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM/EDS). The result of FTIR identified both hydroxyl (–OH) and carbonyl (C=O) groups indicating the presence of phenolic compounds in the extract whereas the analysis obtained from UV-Vis showed a peak absorption spectrum at 268 nm. The electrochemical analysis indicated an excellent inhibition efficiency up to 96.12% for the immersed mild steel coated with 6% of LLE coating. Furthermore, based on the study of polarization, a drastic decrease of corrosion rate at 0.2791 mm/year was observed for the same coating as compared to the uncoated substrate, which was 2.3991 mm/year. The study also confirmed that LLE acts as a mixed type inhibitor, as shown in the polarization curve. The morphological evaluation displayed a smooth and homogenous surface with less salt precipitation for 6% of LLE coating as compared to other types of coating affirming it to be the optimum concentration for this evaluation study.