Natural products as a source of environmentally friendly corrosion inhibitors of mild steel in dilute sulphuric acid: Experimental and computational studies

Abstract

The inhibitory effect of Acacia cyanophylla leaves extract (ACLE) on Mild steel corrosion in 1 M H2SO4 solution was investigated using polarization techniques and electrochemical impedance spectroscopy. Polarization measurements show that the natural extract acted as a mixed inhibitor. Maximum inhibition efficiency was 84% at 25 ± 1°C and 200 ppm inhibitor concentration. Adsorption behavior of the extracts was found to obey Langmuir isotherm model as a most suitable adsorption mechanism. The values of standard adsorption free energy were negative indicating the spontaneous adsorption process. Quantum chemical calculations gave some electronic properties of the molecules of ACLE extracts so as to ascertain any correlation( s) between the corrosion inhibition and molecular structures.