Experimental and Theoretical Studies of the Corrosion Inhibition Performance of a Quaternary Phosphonium-Based Ionic Liquid for Mild Steel in HCl Medium

The corrosion inhibition performance of a quaternary phosphonium-based ionic liquid, i.e., hexadecyltriphenylphosphonium bromide (HPP), on mild steel in 1 M HCl solution was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. surface characterization examined scanning electron microscopy with energy-dispersive X-ray (SEM-EDS). results revealed that the efficiency increases its increasing concentration, it can reach up to 99.1% at concentration 0.07 mM HPP. PDP data showed absorption HPP conformed Langmuir adsorption, which served as mixed-type inhibitor, involving chemisorption physisorption. SEM analysis confirmed formation barrier film metal surface, inhibiting acid attack. Moreover, density functional theory (DFT) calculations molecular dynamics (MD) simulations were conducted elucidate adsorption mechanism inhibitor molecules surface. A match between experimental theoretical findings evidenced.