Experimental and Theoretical Studies of Inhibitive Behaviour of Millet Starch on the Corrosion of Aluminium in Sulphuric Acid Environment

Abstract

The corrosion inhibition of aluminium in 2 M H2SO4 by millet starch was investigated using gravimetric technique at 35-65OC and theoretical quantum chemical computations. The results indicate that millet starch functioned as a good inhibitor for acid induced corrosion of aluminium. It was found that increase in inhibition efficiency of the inhibitor was concentration dependent and also addition of potassium iodide increased inhibitive performance of the inhibitor synergistically. Furthermore, the mode of adsorption process of the inhibitor was best modeled using Langmuir adsorption isotherm at all inhibitor concentrations and temperatures studied. The trend of inhibition efficiency with temperature, calculated values of free energy, activation energy and enthalpy of adsorption was used to propose the inhibition mechanism. Theoretical chemical quantum computations were carried out using density functional theory to underscore the relationship existing between the inhibitive performance of millet starch and electronic properties of millet starch. Finally, Molecular dynamic simulations were performed using Forcite quench molecular dynamics to model lowest energy adsorption configurations of the starch molecule on Al surface and to determine the binding energy of adsorption