Electrochemical evaluation of the corrosion inhibition effect of essential oil extracts on mild steel in acidic environments

Abstract

The corrosion inhibition property of the combined admixture of neem leaf and basil oil extracts (NB) on mild steel in in 1M H2SO4 and HCl solution was studied with weight loss measurement, potentiodynamic polarization and optical microscopy analysis. Results shows NB performed effectively at all concentration studied in HCl solution with average inhibition efficiency above 94% and 91% (weight loss and polarization test) whereas the compound performed poorly in H2SO4 solution at all concentrations (excluding highest concentration, 2.5%) with average inhibition efficiency of 17% and 31%. At 2.5% concentration in H2SO4, the inhibition efficiency is 98.34% and 85.36%. NB exhibited mixed type inhibition property from the polarization plots. This observation was further confirmed from optical characterization of the steel surfaces where the morphology of the inhibited steel was relatively smooth while the non-inhibited morphology was badly corroded with visible corrosion pits.