Henna extract as green corrosion inhibitor for carbon steel in hydrochloric acid solution

Abstract

The extract of henna (Lawsonia Inermis) leaves have been evaluated as a green corrosion inhibitor for carbon steel (C-steel) in 1M HCl solution, utilizing mass loss (ML), potentiodynamic polarization (PP), AC impedance spectra (EIS) and electrochemical frequency modulation (FEM) techniques. The surface analysis was performed using energy dispersion spectroscopy (EDX) and scanning electron microscopy (SEM) methods. The inhibiting property of the extract is familiar with the presence of Lawsonia as a major constituent in the extract. PP study revealed that the adsorption of the extract affects both anodic and cathodic reactions. The inhibitor efficiency (IE %) was found to improve with rising the extract concentration and reached 83.1% at 300 ppm. On the other hand, the PE% was lowered by raising the temperature. The adsorbed Henna molecules on C-steel obeys Langmuir isotherm. The results achieved by different tests are close to each other.