Simple preparation and characterization of novel 8-Hydroxyquinoline derivatives as effective acid corrosion inhibitor for mild steel: Experimental and theoretical studies

Abstract : The primary objectives of the project are the synthesis of new families of heterocyclic compounds based on 8-hydroxyquinolinenamely: 5-((2-bromoethoxy) methyl) quinolin-8-ol (QC2-Br) and 5-((3-bromopropoxy) methyl) quinolin-8-ol (QC3-Br) and their evaluations as inhibitors of acid corrosion (1.0 M HCl).The synthesis of this series of compounds was carried out by a very simple and effective method, but with very good yield and with very good solubility in common organic solvents.The characterization of these new compounds carried out by infrared (FT-IR), nuclear magnetic resonance (1H and 13C NMR) and elementary analysis (EA).The anticorrosion activity was evaluated by gravimetric (WL), electrochemical methods (PDP and EIS) and theoretical studies (DFT, MC and MD). The inhibitors studied adsorbed on the metal surface according to Langmuir isotherm and act on the metal surface as inhibitors mixed type. The thermodynamic parameters show that the two inhibitors adsorb on the metal surface by chemical bonds (chemisorptions).A CPE, Q determined by fit and graphical methods plotted by synthetic data, was utilized.The statistical studies were carried out to confirm the gravimetric tests.Gravimetric solutions were analyzed by Inductively Coupled Plasma-Optical Spectroscopy (ICP-OES) and UV-visible spectrometry (UV-vis). The surface morphology was characterized by Scanning electronic spectroscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and Infrared spectroscopy (FT-IR).The analysis of gravimetric solutions by ICP-OES and UV-visible show that the two inhibitors capable of making chemical bonds with ferric ions and decrease the dissolution of iron in the corrosive solution.The theoretical, experimental results and surface characterization methods show that the two compounds have a good inhibitor of acid corrosion and the inhibitory efficacy exceeds 96% for the two compounds at a concentration of 1 mM.