GUINEA GRASS EXTRACT AS A GREEN CORROSION INHIBITOR FOR MILD STEEL IN AN ACIDIC MEDIUM

 ABSTRACT

Corrosion is a natural process in which metals and alloys attempt to return to their more stable thermodynamic state as a result of chemical attack or reactivity with their surroundings. Corrosion inhibitors are compounds that are applied to a corrosive medium to reduce the potential risk of corrosion, green corrosion inhibitors are biodegradable and free of heavy metals with less hazardous chemicals. The inhibition effect of guinea grass extract (Megathyrus maximus) on the corrosion of mild steel in 0.05M HCL solutions was studied by gravimetric weight loss measurements with concentrations (0.1–0.5 g/l), temperatures (25-55°C) and immersion time (4hr). Inhibition was found to increase with increasing concentration of the extract with a maximum inhibition of 88.89% at a concentration of 0.5g/l in room temperature but decreased with increasing temperature. The adsorption of the extract best fit the Temkin adsorption isotherm, and has a first-order adsorption kinetics with an activation energy of 21.1 kJ/mol. The FTIR studies shows the presence of O-H, C-H, C=C and aromatic ring functional groups. In the atomic absorption spectroscopy, the Fe²⁺ in the sample was observed to decrease as the concentration of Megathyrus maximus extract in the solution increased. These results suggest that extract could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid medium.