PLECTRANTHUS AMBOINICUS LEAVES EXTRACTS – A GREEN CORROSION INHIBITOR FOR MILD STEEL IN SEA WATER MEDIUM

Abstract

The anti-corrosion behavior of Plectranthus Amboinicus leaves extracts in Sea water solution on mild steel werestudied using gravimetric method (weight loss method), electrochemical method (potentiodynamicpolarisation) and scanning electron microscope(SEM) techniques. The extracts were shown to have good inhibition efficiencies for the gravimetricand electrochemical methods. Synergistic effect exists between the Plectranthus Amboinicus - Zn2+ system in controlling the corrosion of mild steel immersed in sea water in the absence and presence of Zn2+. The formulation consisting of 250 ppm Plectranthus Amboinicus, 50 ppm of Zn2+ have 97% inhibition efficiency. A more stable and compact protective film formed on the metal surface. Polarization study reveals that the Plectranthus Amboinicus- Zn2+system function as cathodic inhibitor. The FT-IR and SEM analysis reveal that the protective film is formed on the metal surface.