In depth analysis of anti corrosion behaviour of eco friendly gum exudate for mild steel in sulphuric acid medium

Abstract

The current research work was keen to examine the corrosion inhibition efficiency of mild steel (MS) in presence of aqueous extract of Araucaria heterophylla Gum (AHG) in 1 M H₂SO₄ medium. The phytoconstituents of the AHG were interpreted by GC-MS and corrosion inhibition efficiency was deduced using other techniques like weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Adsorption of inhibitor molecules on the mild steel surface was supported by Density Functional Theory (DFT) studies, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). It is seen from the results that the inhibitor exhibits optimum efficiency of 78.57% at 0.05% v/v on mild steel specimen in 1 M H₂SO₄ medium at room temperature. Tafel polarizations clearly show that the aqueous extract of AHG acts as a mixed type inhibitor. The change in the EIS parameters in presence of inhibitor is investigative of the protective layer formation of the mild steel surface. The adsorption is found to obey Langmuir adsorption isotherm. Thermodynamic and activation parameters for the corrosion inhibition process supported the physical adsorption mechanism.

Keywords:

• GC-MS
• Tafel polarization
• electrochemical impedance
• DFT
• surface morphology

Disclosure statement

No potential conflict of interest was reported by the authors.