Abstract

Corrosion is an electrochemical process that brings about gradual deterioration of metallic surfaces as it reacts with their environment causing the metal to lose its characteristic properties due to surface wear off. This study aims at investigating the corrosion inhibition ability Ficus exasperata extract can exert on mild steel. The inhibition of mild steel from corrosion in tetraoxosulphate VI acid solution by methanolic extract of Ficus exasperata leaves was investigated using gravimetric weight loss method. The effects of concentration, immersion time and temperature for mild steel corrosion in 0.5M H2SO4 solution were studied. The kinetics, thermodynamics and adsorption isotherm studies were also investigated, the phytochemical and FTIR studies were also investigated. It was discovered that the inhibition efficiency increased with increase in extract concentration but decreased at elevated temperature. Corrosion rate was observed to increase with time but decrease with extract concentration. The kinetic studies were observed to follow first order reactions. The thermodynamic studies showed that corrosion inhibition may be as a result of non spontaneous mixed adsorption of the plant constituents on the surface of the metal. The positive enthalpy results show the endothermic nature of the mild steel dissolution process, while the negative entropy showed that the inhibitor molecules move without interruption in the bulk solution and adsorbed in orderly manner onto the surface of the mild steel. Experimental data fitted all adsorption isotherms investigated. The study showed that the methanolic extract of Ficus exasperata leaves has the ability to serve as a bio inhibitor for corrosion of mild steel.

Keywords: Characterization, Ficus exasperata, corrosion, mild steel