CHARACTERIZING THE PR0TECTIVE ACTION OF DACRYODES EDULIS ON MILD STEEL CORROSION IN DIFFERENT ENVIRONMENT

Abstract

The toxic effects of synthetic corrosion inhibitors have led to the search for naturally occurring substances which are not only readily available but are also environmentally friendly. This study investigates the corrosion inhibition efficacy of ethanol extract of the leaves Dacryodes edulis (DE) on mild steel in 0.1M H2SO4 and 0.5M NaCl by weight loss method and potentiodynamics polarization technique. The experiment was performed at different immersion periods (3hrs, 6hrs, 24hrs. 72hrs, 144hrs, 216hrs and 288hrs) and concentration of the inhibitor. Result obtained reveals that inhibition efficiency was markedly high on the addition of the plant extract.  Highest inhibition efficiency of 94.8% was noted in 0.5 M NaCl and 92.2% in 0.1M H2SO4 after 72 hours. Electrochemical studies revealed that the plant extracts is a mixed type inhibitor but predominantly cathodic. The efficacy of the plant extract as a good corrosion inhibitor may be due to the spontaneous physical adsorption of the plant constituents on the surface of mild steel. Experimental data fitted with the Langmuir adsorption isotherm. Keywords: Corrosion inhibition, mild steel, corrosion rate, inhibition efficiency, adsorption, Dacryodes edulis