Corrosion inhibitive properties and adsorption behaviour of ethanol extract of Piper guinensis as a green corrosion inhibitor for mild steel in H2SO4

Abstract

The corrosion inhibition of mild steel by ethanol extract of Piper guinensis (EEPG) has been studied using gravimetric, gasometric and thermometric methods. The results of the study reveals that the different concentrations of ethanol extract ofPiper guinensis (EEPG) inhibit mild steel corrosion. Inhibition efficiency of the extract is found to vary with concentration, temperature and period of immersion. Values of activation energy of the inhibited corrosion reaction of mild steel are greater than the value obtained for the blank. Thermodynamic consideration reveals that adsorption ofP. guinensis extract (EEPG) on mild steel surface is spontaneous and occurs according to Langmuir adsorption isotherm. Physical adsorption mechanism has been proposed for the adsorption of the inhibitor from the trend of the inhibition efficiency with temperature and the values of some kinetic and thermodynamic parameters obtained.                                             Key words: Corrosion inhibition, mild steel, Langmuir adsorption isotherm, physical adsorption, Piper guinensis.