Corrosion inhibition by an aqueous extract of Phyllanthus amarus

Abstract

The inhibition efficiency (IE) of phyllanthus amarus extract (PAE)-Zn 2+system, in controlling corrosion of carbon steel in an aqueous solution containing 60 ppm of Cl -, has been evaluated by weight loss method. Weight loss study reveals that the formulation consisting of 2 mL of PAE and 25 ppm of Zn 2+ has 98% inhibition efficiency in controlling corrosion of carbon steel immersed in an aqueous solution containing 60 ppm of Cl -. Synergistic parameters suggest that a synergistic effect exists between PAE and Zn 2+. Polarization study reveals that this system functions as mixed type of inhibitor controlling the cathodic reaction and anodic reaction to an equal extend. AC impedance spectra reveal that a protective film is formed on the metal surface. The FTIR spectra reveal that the protective film consists of Fe 2+-phyllanthus complex.