Study of Extracts of A. rusticana as Corrosion Inhibitors of Mild Steel in 1 mol L^-1 HCl Solution Using MALDI-TOF-MS

Corrosion studies were performed using extracts of Armoracia rusticana and their fractions through mass loss measurements, electrochemical impedance, and potentiodynamic polarization at concentrations of 100, 200, 400, 800, 1600, and 3200 mg L^-1 in 1 mol L^-1 HCl. The Fourier transform infrared, ESI-MS(±), MALDI-FT-ICR(±), and MALDI-TOF(±) techniques were used for the chemical characterization of the extracts and their fractions. The ethyl acetate fraction of the crude ethanolic extract (WEP-EtOAc) showed the highest inhibition efficiency, above 96%, verified by mass loss measurement with and without temperature variation and electrochemical tests. Scanning electron microscopy and X-ray photoelectron spectroscopy analyses were performed for the surface analysis. MALDI-TOF was also used for the ethyl acetate fraction of WEP, where the laser was applied directly to the metal plate under study. Even after washing, the glucosinolate chemical group was identified as the major component on the metal surface. This study suggests that glucosinolates are the possible main corrosion-inhibiting phytochemicals in the extract.