Electrochemical and theoretical insights on the adsorption and corrosion inhibition of novel pyridinium-derived ionic liquids for mild steel in 1 M HCl

The corrosion protection performance of new synthesized ionic liquids derived from pyridine namely: 1-ethyl-4-(2-(4-fluorobenzylidene)hydrazinecarbonyl)pyridin-1-ium iodide (IPyrC(2)H(5)), and 1-butyl-4-(2-(4-fluorobenzylidene)hydrazinecarbonyflpyridin-1-ium iodide (IPyr-C4H5) was investigated against mild steel corrosion in 1 M HCl by using electrochemical methods. PDP experiments revealed that the IPyr-C2H5 and IPyr-C4H5 behaved as anodic type inhibitors. Electrochemical impedance spectroscopy (EIS) measurements indicated that both compounds could inhibit the corrosion of mild steel with an inhibition efficiency of 88.8% for IPyr-C2H5 and 92.3% for IPyr-C4H5 at optimum concentration after 30 min of immersion. These compounds can be adsorbed on the mild steel surface through physical and chemical bonds, according to Langmuir isotherm model. INT method was employed to correlate the molecular structure of pyridinium-derived ionic liquids and their experimental inhibition efficiencies. Molecular dynamics (MD) studies revealed higher interaction energy for inhibitor IPyr-C4H9 compared to IPyr-C2H5. The radial distribution function (RDF) indicated chemical adsorption of the inhibitors on the metallic surface. (C) 2020 Elsevier B.V. All rights reserved.