Acid corrosion inhibition of ferrous and non-ferrous metal by nature friendly Ethoxycarbonylmethyltriphenylphosphonium Bromide (ECMTPB): Experimental and MD simulation evaluation

Abstract

Electrochemical techniques, using galvanostatic polarization and electrochemical impedance spectroscopy (EIS) as experimental; Quantum Chemical (QC) calculation and Molecular dynamics (MD) simulation as theoretical methods and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) as surface morphological studies have been accomplished to evaluate the corrosive inhibitive property of Ethoxycarbonylmethyl Triphenylphosphonium Bromide (ECMTPB) for Mild Steel (MS) in 0.5 M H2SO4 and Aluminium (Al) in 0.5 M HCl solutions, respectively. The protective rate of both the materials increased with increase in the concentration of 10−5 M to 10−2 M of ECMTPB as well as with room temperature. The Nyquist plot of impedance expressed mainly as a depressed capacitive loop with different concentrations. The mechanism of inhibition of corrosion of MS and Al in acidic medium follows Langmuir adsorption isotherm and inhibitor is being chemisorbed predominantly on the metal surface. The images found from Surface Morphological Studies Viz., SEM with EDX supplements the results obtained from the experimental and theoretical studies. The properties of single ECMTPB molecule from QM and the interaction energies between inhibitor and metals from classical simulations indicate the possible mechanism of preventing corrosion of inhibitor.