Inhibitory action of Spondias mombin leaves extracts on corrosion of mild steel in 1M HCl

Abstract

Acid corrosion of steel and its associated financial and material costs are serious challenges to the chemical industry, and protecting these alloys through the use of effective corrosion inhibitors is imperative. In this study, the corrosion inhibition of mild steel in 1M HCl media using water and ethanol extracts of Spondias mombin leaves was investigated via weight loss technique, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The influence of temperature on inhibitor behaviour was also studied. Both extracts inhibited corrosion of mild steel via adsorption, following the Langmuir and Freundlich isotherms. The inhibition efficiency (IE) increased as extracts concentration was increased. After 24 and 72 hours exposure in the acid solution at 25 ℃, 500 ppm of extracts delivered maximum efficiency of (94.44 % and 76.52% for ethanol) and (51.52 % and 58,97 % for water). However, increasing temperature to 40 ℃ and 60 ℃ (after 24 hours) significantly boosted the efficiency of water extract (favoring inhibition via combined physical and chemical adsorption) but depreciated the performance of ethanol extract. The extracts provide good protection to mild steel in acidic environment and are therefore recommended as green alternatives to existing toxic ones.