Aqueous extract of Argemone mexicana roots for effective protection of mild steel in an HCl environment

摘要

The inhibition effect of aqueous Argemone mexicana root extract (AMRE) on mild steel corrosion in 1 M HCl has been studied by weight loss, Tafel polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy techniques. Results indicate that inhibition ability of AMRE increases with the increasing amount of the extract. A maximum corrosion inhibition of 94 % is acknowledged at the extract concentration of 400 mg L-1. Polarization curves and impedance spectra reveal that both cathodic and anodic reactions are suppressed due to passive layer formation at the metal-acid interface. It is also confirmed by SEM micrographs and FTIR studies. Furthermore, the effects of acid concentration (1-5 M), immersion time (120 h) and temperature (30-60 A degrees C) on inhibition potential of AMRE have been investigated by the weight loss method and electrochemical techniques. An adsorption mechanism is also proposed on the basis of weight loss results, which shows good agreement with the Langmuir isotherm.