INHIBITORY ACTION OF MACARANGA PELTATA LEAVES EXTRACT ON THE CORROSION OF MILD STEEL IN 0.5 M SULPHURIC ACID- QUANTUM CHEMICAL APPROACH

Abstract

Weight loss and electrochemical impedance spectroscopy (EIS) method were used for testing the corrosion inhibition effect of Macaranga peltata leaves (MPL) extract on corrosion of mild steel in 0.5 M sulphuric acid solution. The inhibitory effect of MPL was studied at various concentrations of the extract and different time of immersion. In all cases an optimal efficiency was found out. Maximum inhibition efficiency was 92.6% for 5%v/v at 5 h. Nyquist and Tafel plots gave a confirmation about the inhibitory action of the plant extract, agreeing with the weight loss method. The surface content of mild steel after immersion was investigated using IR and the inhibition mechanism is suggested as adsorption of the phytochemical constituents from the results. The Quantum chemical energy calculations become an additional support of the suggested mechanism.