Inhibitive Performance of Bitter Leaf Root Extract on Mild Steel Corrosion in Sulphuric Acid Solution

Abstract

Cost of organic and some inorganic inhibitors are relatively low but many of the effective inhibitors such as chromate, arsenate and ethanolamine are very toxic, harmful to human health and their environment. The inhibitive ability of Bitter leaf (Vernonia amygdalina) root extract was investigated on corrosion of mild steel in 1.5 M Sulphuric acid solution using weight loss, hydrogen evolution and thermometric measurements at temperature ranges of 30-60°C. The root extract was characterized for phytochemical screening using Gas Chromatography Mass Spectroscopy (GCMS) and Fourier Transformation Infra-Red Spectroscopy (FTIS). The result showed the extracts contained some organic compounds which are responsible for the inhibitive ability. The corrosion rate of mild steel in the presence of inhibitors decreases and increase as the temperature increases. The inhibitor exhibit excellent inhibition efficiency on mild steel corrosion in H2SO4 solution as 90 %, 84.82 %, 79.65 % and 76.90 % of inhibition efficiency achieved with addition of 0.5 g/l concentration of bitter leaf root extract (BLRE) at 30°C, 40°C, 50°C and 60°C temperature respectively. The inhibition efficiency increase with in concentration of inhibitor and decreases with rise in temperature. The adsorption parameters also obeyed the Langmuir adsorption isotherm and the result of Gibbs free energy of adsorption (∆Gads) showed spontaneous process of adsorption that is consistent with physical adsorption mechanism.