Natural Products for Material Protection: Inhibition of Mild Steel Corrosion by Date Palm Seed Extracts in Acidic Media
By Umoren, Saviour A.; Gasem, Zuhair M. & Obot, Ime B.
Published in Industrial & Engineering Chemistry Research
2013
Abstract
The corrosion inhibition effect of date palm (Phoenix dactylifera) seed extracts for mild steel in 1 M HCl and 0.5 M H2SO4 solutions was investigated by weight loss and electrochemical methods. The inhibition efficiency increased with an increase in the extract concentration and decreased with an increase in the temperature. Extract concentrations of 2.5 and 1.5 g L -1 gave maximum inhibition efficiencies in 1 M HCl and 0.5 M H2SO4, respectively. The immersion time was also found to influence the corrosion inhibition effect in both acidic media. Polarization curves indicate that the extract functions as a mixed inhibitor, affecting both the anodic and cathodic partial reactions of the corrosion process. Adsorption of the extract onto a mild steel surface followed the Langmuir adsorption isotherm. The mechanism of physical adsorption has been proposed based on the trend of the inhibition efficiency with temperature. The date palm seed extract is a better corrosion inhibitor for mild steel in HCl than in a H2SO4 solution.