A COMPARATIVE STUDY OF VITEX DONIANA AND PTEROCARPUS SOYAUXI AS CORROSION INHIBITORS OF MILD STEEL IN HCL MEDIUM

Corrosion inhibition of mild steel using Vitex doniana (VD) and Pterocarpus soyauxi (PS) leaves extract were studied using thermometric and gasometric methods at 30oC and 60oC. The inhibition efficiency was found to increase as the concentration of extracts increase from 0.1g/l to 0.5g/l with Pterocarpus soyauxi having the highest inhibition efficiency of 70.67% from Thermometric and 69.28% from gasometric method, while Vitex doniana has 68.49% from thermometric and 68.28% from gasometric all at 30oC. Adsorption of Vitex doniana leaves extract on the surface of the mild steel obeyed Langmuir and Tempkin adsorption isotherm while that of Pterocarpus soyauxi leaves extract on the surface of the mild steel followed Tempkin and freudlich isotherm. From the values obtained from the degree of surface coverage, Ea, ?H and ?G was calculated and all indicated physical adsorption