Eco-friendly corrosion inhibitors: inhibitive action of ethanol extracts of Garcinia kola for the corrosion of mild steel in H2SO4 solutions

摘要

Purpose - This paper aims to investigate the inhibitive effect of ethanol extracts of Garcinia kola (EXG) for the corrosion of mild steel in H2SO4solutions. The study is another trial to find a cheap and environmentally safe inhibitor for mild steel corrosion.Design/methodology/approach - The inhibition efficiency has been evaluated using the hydrogen evolution technique at 30-60°C. The mechanismof adsorption inhibition and type of adsorption isotherm were proposed based on the trend of inhibition efficiency and kinetic data.Findings - The results obtained indicate that EXG inhibits the corrosion of mild steel in acidic medium and that the inhibition efficiency increases withan increase in the concentration of ethanol extracts and decreasing temperature. The inhibition efficiency increased on addition of potassium iodide toEXG, indicating synergism. The experimental data obeyed the Langmuir adsorption isotherm as well as the El-Awady et al. thermodynamic-kineticmodel. The activation energy of inhibition of 6.8508 KJ/mol calculated for the corrosion process suggests that the EXG molecules are physicallyadsorbed on the metal surface.Research limitations/implications - Further investigations involving electrochemical studies such as polarization method will provide furtherenlightenment on the mechanistic aspect of the corrosion inhibition.Originality/value - This paper provides new information on the possible application of EXG as an environmentally friendly corrosion inhibitor underthe specified conditions. This environmentally friendly inhibitor could find possible applications in metal surface anodizing and surface coatings.