Inhibition, Adsorption and Thermodynamic Investigation of Iron Corrosion by Green Inhibitors in Acidic Medium

The corrosion inhibition potentials of alkaloid, saponin and flavonoid extracts of Ocimunbasilicum leaves were investigated by evaluating the corrosion behaviour of Iron immersed in 1.0 M H2SO4 solutions containing varied concentration of the extract (0.5 g/L, 1.0 g/L, 2.0 g/L, 3.5 g/L, 5.0 g/L, 7.5 g/L and 10.0 g/L) using chemical methods. Maximum temperature attained, reaction time, thermodynamic data and adsorption characterizations were utilized to evaluate the corrosion inhibition and adsorption properties of the extract. The results revealed that, the corrosion of Iron decreases with increase in concentration of alkaloid extract, saponin extract and flavonoid extract, also, increases with increase in H2SO4 concentration. The increase in addition of the green inhibitors to the corrosive medium, improve the values of inhibition efficiency of the extract in the order AEOBL > SEOBL > FEOBL. In all cases, Flavonoid extracts exhibits least effect on the corrosion of Zinc in comparison with alkaloids and saponins. Results obtained from adsorption studies indicated that, all the green inhibitors were adsorbed on the surface of the Iron and that the adsorption fit excellently with the assumptions of the Langmuir adsorption isotherm model. All data acquired revealed that Ocimunbasilicum leaves are efficient inhibitors of corrosion in acid medium due to the presence of heterocompounds: saponins, tannins, flavonoids, glycosides, carbohydrates, reducing sugars, terpenoids, steroids and alkaloids.