Aspilia Africana extracts as organic corrosion inhibitor of mild steel in corrosive acidic media.

Abstract

Extracts of Aspilia Africana as organic corrosion inhibitor of mild steel in corrosive media of sulphuric acid (H 2 SO 4) and hydrochloric acid (HCl) has been investigated at room temperature of 25.6 o C using gravimetric (weight loss) technique. Mild steel coupons of 30 mm 2 and 0.45 mm thickness were exposed for varying durations in steps of 24 hours, in 0.5M of H 2 SO 4 and 0.5M HCl mixed with varying concentrations of Aspilia Africana extract (100mg/L-700mg/L). The results show that corrosion rates dropped from maximum value of 8.3x10-3 mpy (mills per year) for the uninhibited medium to maximum value of 1.5x10-3 mpy for the inhibited medium of 0.5M H 2 SO 4 with extract concentration of 100 mg/L. Corresponding values for 0.5M HCl are 10.0x10-3 to 2.5x10-3 mpy. Further increases in the extract concentrations result in less drastic decrease in the corrosion rate as reported in this paper. Values of corrosion inhibition efficiencies of 58.5-98.8% for H 2 SO 4 and 70-90.9% for HCl media occurred for various extract concentrations with the highest values occurring at 600mg/L. Thus, Aspilia Africana extracts whose plants are bountiful in the tropical forests of West, East and Central Africa, provide good corrosion inhibition for mild steel.