Comparative study of the inhibition effects of alkaloid and non alkaloid fractions of the ethanolic extracts Of <i>Costus afer</i> stem on the corrosion of mild steel in 5 M HCl solution

Abstract

The Alkaloid and Non- alkaloid fractions of the ethanolic extracts from Costus afer (AECA and NAECA) were comparatively studied for their inhibitive properties on the corrosion of mild steel in 5 M HCl solution using Gravimetric and Gasometric techniques. The results revealed that both extracts inhibited the corrosion of mild steel in HCl solution following the order: NAECA > AECA. The maximum inhibition efficiencies obtained were 49.2 % for AECA and 86.4% for NAECA at an inhibitor concentration of 5 g/L. Inhibition efficiency was found to increase with increase in concentration and increase in temperature. The adsorption of both extracts on the mild steel was found to be consistent with Langmuir adsorption isotherm.Physical adsorption mechanism was proposed for the adsorption of the components of the extracts on the mild steel surface.

KEYWORDS: Adsorption; Alkaloid; Corrosion inhibition; Non-alkaloid; Mild steel.