Inhibition of Acid Corrosion of Mild Steel Using Delonix regia Leaves Extract

Abstract

The inhibition efficacy of aqueous extracts of the leaves of Delonixregia (DR) in 1 M HCl and 0.5 M H 2 SO 4 have been investigated using weight loss, electrochemical and surface probe techniques. DR extract inhibited mild steel corrosion in both acidic environments via adsorption of the extract organic matter on the metal/solution interface. Potentiodynamic polarization results indicate that DR is a mixed type inhibitor in both acidic environments, whereas the impedance results revealed adsorption of the DR species on a corroding steel surface. Increase in inhibition efficiency was concentration dependent. The adsorption followed Langmuir adsorption isotherm. Scanning electron microscopy (SEM) results revealed the formation of a protective layer adsorbed on a mild steel surface in the acid solutions.