Adsorption Studies on the Inhibitive Properties of Aqueous Extracts of Theobroma cacao (TC) Leaves on Mild Steel in 1.0 M HCl

Abstract

Okoche Kelvin Amadi*, Onyinyechi Uloma Akoh, Godson Chukwudi Eric     

Corrosion of mild steel is an impactful environmental process because the electrochemical degradation process operates to severely waste the usefulness of the metal. The consideration of the various industrial installations that use mild steel for their construction, the present investigation is aimed at employing Theobromao cacao  leaf extract to protect against mild steel deterioration through the inhibition method with due consideration of the influence of factors such as temperature, concentration,  time, etc. .. The results of the investigations indicated that aqueous extract of the cocoa leaf inhibited mild steel corrosion with efficiencies ranging from 63.36 – 77.64 % at 302K. However, maximum inhibition efficiency of 83.21 % was observed at extract concentration and temperature of 1000 ppm and 323 K respectively. The behaviour of the inhibitor showed pronounced patterns that supported a physicoadsorption mechanism and model fitness that is consistent with the  Freundlich and El-Awardy adsorption models. The adsorption of the inhibitor was observed to prevent the diffusion of the acid unto the active sites that could have enhanced corrosion An exothermic and spontaneous adsorption were upheld based on the positive values observed for the enthalpy change and the negative values of standard free energy of adsorption.