ABSTRACT
Soy polymer was extracted from soybean [Glycine Mac-L] and used in studying the corrosion inhibition of mild steel in 2 molar mass solution of hydrochloric acid and compared with the corrosion inhibition properties of poly [vinyl pyrrolidone] in the same acidic medium, using hydrogen evolution method at temperature range of 25-60OC and inhibitor concentration range of 0.01-0.2g/mol. The result of the study shows that soy polymer has higher inhibition efficiency than poly [vinyl pyrrolidone] PVP. The corrosion rate decreased with increasing concentration of soy polymer and PVP while the inhibition efficiency [%1] of both decreased with increased in temperature. The highest value of activation energy obtained with the inhibitors was 62.8kj/mol which supports the mechanism of physical adsorption since it is less than 80.0kj/mol. The negative values of free energy of adsorption ∆Gasd which ranged from – 8.1 to – 3.6 at 60OC and – 17.5 to – 8.7 kj/mol at 25OC suggest spontaneous adsorption. The inhibitors were found to obey Freundlich adsorption isotherm. The soy polymer is more environmentally friendly and more corrosion inhibitive than poly [vinyl pyrrolidone].
