COMBATING CORROSION OF MILD STEEL IN HYDROGEN TETRAOXOSULPHATE (VI) ACID ENVIRONMENT USING GREEN CORROSION INHIBITORS: Chysophyllum albidum PLANT

The corrosion inhibition performance of the ethanol extracts of Chysophyllum albidum leaves (EECAL) and stem (EECAS) on the corrosion of mild steel in 0.5 M H2SO4 solution at 303 K and elevated temperatures 303 and 323 K was investigated and compared. The experimental work was performed by the use of weight loss method (gravimetric) and hydrogen evolution (gasometric) techniques respectively. The results indicate that both plants extracts inhibit the corrosion of mild steel in the medium. However, EECAS exhibits higher maximum inhibition efficiency (90.7%) than EECAS (80.3%) at 4.0 g/L. Generally inhibition efficiency was found to increase with increase in concentration of both plant extracts but decreased with rise in temperature. Adsorption of both extracts on the mild steel coupon was found to obey the Langmuir adsorption isotherm. The phenomenon of physical adsorption is proposed from the obtained thermodynamic parameters as equilibrium constant (Kad) showed a decrease with increased temperature, free energy of adsorption (-∆Goad) values were more negative than 40 kJ/mol.