Corrosion inhibition and adsorption properties of ethanol extract of Gongronema latifolium on mild steel in H2SO4

Purpose ‐ The purpose of this paper is to study the inhibitive and adsorptive characteristics of ethanol extract of Gongronema latifolium (GL) as a corrosion inhibitor for mild steel in H2SO4. Design/methodology/approach ‐ The inhibition efficiencies were evaluated using thermometric and hydrogen evolution techniques. Findings ‐ The inhibition efficiency of ethanol extract of GL vary with concentration of the extract, period of immersion and with temperature. The extract acts as an inhibitor because of its phytochemical and amino acid composition. The extract is adsorbed spontaneously on the surface of mild steel according to Langmuir adsorption isotherm. The mechanism of physical adsorption is proposed from the trend of the inhibition efficiency with temperature and the values of some kinetic and thermodynamic parameters obtained. Research limitations/implications ‐ The study provides information on the use of ethanol extract of GL as a corrosion inhibitor. Electrochemical studies such as polarisation and alternating current impedance spectra will throw more light on the mechanistic aspects of the corrosion inhibition. Practical implications ‐ Ethanol extract of GL can be used as an environmentally friendly inhibitor for the corrosion of mild steel in H2SO4. Originality/value ‐ This environmentally friendly inhibitor could find possible applications in metal surface anodising and surface coatings.