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

Simeon C Nwanonenyi,Iheoma C Chukwujike,Vicent C Arinze,Innocent C Madufor

doi:10.18052/www.scipress.com/ijet.8.1

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

Highlights

Aluminium and its alloys are used extensively in various fabrication and construction applications since the inception of industrial revolution
In acidic or alkaline media at high concentration and temperature respectively the corrosion agent in the media breaks down the oxide film which subsequently exposes the bare aluminium surface to degradation [3]
Corrosion rates and inhibition efficiency The dissolution of aluminium coupons in 2 M H2SO4 in the absence and presence of different concentrations millet starch for 24 h was determined at 35-65OC using weight loss technique

Summary

Introduction

Aluminium and its alloys are used extensively in various fabrication and construction applications since the inception of industrial revolution This is as a result of distinct characteristics of aluminium which include: lightness, softness, low cost, light reflectivity, passivity, formability, heat and thermal conductivity, etc [1,2]. The exploration of natural products from plant origin as corrosion inhibitor should be of considerable great importance. This is basically due to their low cost considerations, availability, renewable sources, ecological acceptance, other chemical constituents containing hetero-atoms either in long chain system or aromatic structure that have proved to be effective inhibitors [4,5,6,7,8]. Recent literature has shown that despite many sources of starch, only relative few have been explored in inhibiting the corrosion of aluminium [11,12]

Methods

Results

Conclusion