Action of the Capparis Spinoza leaves extract as a green corrosion inhibitor for high carbon steel in acidic solution

Abstract

Capparis Spinoza leaves extract (CS) was studied in HCl (0.5 mol/ L) solution as a green corrosion inhibitor for the HCS using the electrochemical measurements, as potentiodynamic polarization (PdP), and electrochemical impedance spectroscopy (Eis). The PdP plots showed a mixed role of the (CS) extract, and the Eis diagrams pointed that the charge transfer resistance (Rct) increased as the concentration of (CS) increased. Inhibition efficiency reached a maximum of ~ 97%. The corrosion inhibition of HCS in acidic medium showed a good fit to the Langmuir adsorption model. The thermodynamic parameter, as ΔGads was calculated and revealed that (CS) adsorbed onto HCS surface via both chemical and physical adsorption mode. HCS surface morphology was investigated using AFM technique, ultraviolet-visible spectrometry and confirmed that the formation of a protective thin film of (CS) on the metal surface. Quantum chemical calculations were determined and supported the experimental data.