Synergistic combination effect of clove essential oil extract with basil and atlas cedar oil on the corrosion inhibition of low carbon steel

Abstract

Clove essential oil extracts was separately admixed with basil oil extract (CLB) and atlas cedar oil extract (CLA), and studied for their corrosion inhibition properties on low carbon steel in 0.5 M H2SO4 and HCl solutions by coupon analysis, potentiodynamic polarization, open circuit potential measurement and optical microscopy. Results showed the two admixed inhibitor compounds performed effectively at most concentrations with optimal inhibition efficiencies of 95.48% and 95.32% in H2SO4 solution while in HCl the corresponding values are 92.7% and 97.98%. CLB and CLA showed mixed inhibiting properties though shift in corrosion potential and Tafel slope values indicates dominant cathodic inhibition and higher cathodic exchange current density. Severe general deterioration was visible on the morphology of control (no inhibitor) steels in H2SO4 while the morphology of the control steel from HCl showed extensive localized deterioration. Addition of CLB and CLA significantly improved the morphology of the steel in both acid solutions signifying effective corrosion inhibition. The open circuit potential plots of the carbon steel in both acids showed significant potential transients due to thermodynamic instability in the presence of the inhibitors. However, the corrosion potential plots were significantly electropositive relative to the plot of the control specimen with final values −0.448V and −0.452V in H2SO4, and -0.476V in HCl (CLA). Keywords: Carbon steel, Corrosion, Oil, Inhibitor