Evaluation of Anti-corrosive Efficacy of Prosopis Cineraria Extract on the Nitric Acid Corrosion of Copper

Abstract

Anti-corrosive propensity of Prosopis cineraria extract on the corrosion behavior of copper (Cu) in nitric acid (HNO3) medium was investigated by applying gravimetric technique. Corrosion inhibition efficiency of Prosopis cineraria was observed to enhance with increasing concentration of extract and reduce with elevation in temperature. The inhibitor underwent physisorption on the Cu metal surface. Adsorption characteristics were approximated by Langmuir adsorption isotherm. Highest inhibition efficiency (η%) 86.12 % was obtained at 303±1 K in fruit extract. It was observed that the extract acts as a benign potential corrosion inhibitor for Cu corrosion in 1.0 M HNO3 acid solution. Results revealed that existence of Prosopis cineraria extract enhances the energy of activation (Ea) of corrosion reaction. Adsorption parameters such as kinetic and thermodynamic [Gibbs free energy change (ΔG0ads) and adsorption equilibrium constant (Kads)] of adsorption process were determined from experimental data. These parameters show a strong interaction between surface of copper metal and inhibitor extract. The inhibitor adsorption process on surface of copper was found to be physical, exothermic and spontaneous. The surface morphology and characterization of copper was done by applying scanning electron microscope (SEM).