Novel Cu (II) and Zn (II) complexes of 8-hydroxyquinoline derivatives as effective corrosion inhibitors for mild steel in 1.0?M HCl solution: Computer modeling supported experimental studies

Abstract

In this work, we have synthesized and characterized novel complexes of copper (II) and zinc (II). These complexes were obtained by reacting of 5-azidomethyl-8-hydroxyquinoline with copper chloride dihydrate and zinc chloride dihydrate. The isolated complexes were characterized by UV–visible spectroscopy (UV–Vis), Elemental analysis (EA), Infrared (IR), Mass spectrometry (MS) and 1H and 13C Nuclear Magnetic Resonance (NMR). These complexes were tested as corrosion inhibitors of mild steel in 1.0 M HCl by experimental and theoretical investigations. The surface of the steel before and after corrosion was characterized by the Scanning Electron Microscope coupled with Dispersive Energy Analysis (SEM-EDAX) and the gravimetric solution was analyzed by UV–visible spectrometry. The results of electrochemical and theoretical studies and the surface analysis of the steel show that these two complexes are effective for the protection of steel in 1.0 M HCl, but the high-temperature complexes become less effective, in addition, these complexes are adsorbed to the steel surface following the isotherm of Langmuir.