Abstract

The inhibitive action of Polyalthialongifolia bark extracts on the corrosion of mild steel in 0.5 M H₂SO₄ has been studied using the weight loss technique. The concentration of the extract used was varied (0.1, 0.2, 0.3, 0.4, and 0.5) g/l over an exposure period of 24 hours and the temperature variation was 303 k, 323 k and 343 k respectively. The corrosion rates decreased generally with increase in inhibitor concentration. The inhibition efficiency was found to increase with increasing inhibitor concentration. The effect of temperature on the corrosion inhibition of the mild steel indicated an increase in the corrosion rate as temperature increased and subsequent decrease in the inhibition efficiency. Thermodynamic data calculated are suggestive of adsorption of inhibitor molecules on metal surface. Experimental data fitted into Langmuir’s and Temkin’s adsorption isotherms.