Investigation of phytochemical components and corrosion inhibition property of Ficus racemosa stem extract on mild steel in H2SO4 medium

The inhibition of mild steel corrosion in 1N H2SO4 solution by Ficus Racemosa (FR) stem extract has been studied using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) in the temperature range of 298 K-328 K. Inhibition efficiency was found to increase with increasing concentration of the stem extract at all the temperatures. Potentiodynamic polarization data revealed mixed mode of inhibition. Change in impedance parameters with changing concentrations supports the adsorption of inhibitor molecules on mild steel surface. Temperature studies indicated a decrease in inhibition efficiency with rise in temperature. Adsorption of extract molecules on mild steel surface obeyed Langmuir adsorption isotherm. The thermodynamic parameters of the adsorption process were calculated. Major chemical constituents present in the FR stem extract were identified using GCMS which were predominantly classified as triterpenes, sterols, long chain fatty acids, purine nucleosides and long chain alkenes. SEM and AFM analysis confirmed the formation of protective layer on mild steel surface. Results from various studies show that FR stem extract can serve as an effective inhibitor for mild steel corrosion in 1N H2SO4. (C) 2016 Published by Elsevier Ltd.