Chemical, electrochemical and quantum evaluation of L-Methione (LM) as corrosion inhibitor for mild steel in HCl solution

Chemical, electrochemical and quantum chemical techniques were used to study the corrosion inhibition and adsorption processes of L-Methione (LM). The results obtained indicate that the inhibition efficiency increases with decreasing temperature and increasing concentration of inhibitor. It has been shown that the adsorption of LM on mild steel obeys the Temkin adsorption isotherm at all studied temperatures with negative values of ΔGads suggesting a stable and a spontaneous inhibition process. Polarization data show that the compound behaves as a mixed type inhibitor. Polarization parameters were determined with maximum value of inhibition efficiency for 5 x 10-4 M concentration of the inhibitor at 303 K is 79.9 %. From Nyquist plot of electrochemical impedance spectroscopy, polarization resistance (Rp) increased with increasing inhibitor concentration whereas double layer capacitance (Cdl) decreased indicating a decrease in local dielectric constant suggesting that the inhibitors function by forming a protective layer at the metal surface. Quantum chemical approach was further used to calculate some electronic properties of the molecule in order to ascertain any correlation between the inhibitive effect and molecular structure of LM.

Author(s): Ekerete Jackson*, K. E. Essien and I. B. Obot

Abstract | PDF

Share This Article