Novel cost-effective aqueous Amorphophallus paeoniifolius leaves extract as a green corrosion inhibitor for mild steel corrosion in hydrochloric acid medium: A detailed experimental and surface characterization studies

Abstract

Corrosion resistance property of eco-friendly Amorphophallus paeoniifolius leaves (APL) extract on mild steel surface in 1 M hydrochloric acid solution was studied by chemical, electrochemical and surface characterization methods. The functional groups and compositions of pure APL extract and corrosion product were investigated by FT-IR and UV–visible spectroscopy. Experimental methods proved the extent of metal surface deterioration in acidic medium was diminished as the APL extract concentrations increased. Corrosion inhibition mechanism is suggested to be a mixed type based on results obtained by polarization measurements. The data obtained by electrochemical impedance spectroscopic method indicates the development of protective film around the metal surface. Surface morphological studies such as FESEM, contact angle measurements and AFM studies performed on mild steel surfaces further confirm the protective ability of the inhibitor towards corrosion. It was well supported by EDAX studies indicating restricted anodic dissolution reaction in the presence of inhibitor. Adsorption isotherms showed a good fit to Langmuir isotherm and the data obtained indicates the spontaneous adsorption with the majority being physisorption. Thermodynamic and activation parameters showed the efficacy of inhibitor in controlling the corrosion and the efficiency of corrosion inhibition was found to be inversely proportional to the solution temperature. Percentage corrosion inhibition efficiency (92.49) obtained by electrochemical impedance spectroscopy on mild steel for 10% v/v concentration of APL extract was in good agreement with other experimental methods.