Facile preparation of new hydrazone compounds and their application for long-term corrosion inhibition of N80 steel in 15% HCl: An experimental study combined with DFTB calculations

Abstract

Developing safer and environmentally responsible corrosion inhibitors is of great significance for protect-ing pipelines from corrosion damage during acidizing processes. It is a never-ending task for oil service companies and researchers. Herein, new hydrazone compounds, namely (E)-2-(4-isobutylphenyl)-N'-(4-methoxybenzylidene)propanehydrazide (MHDZ), and (E)-N'-(furan-2-ylmethylene)-2-(4-isobutylphe nyl)propanehydrazide (FHDZ), bearing ibuprofen moiety were synthesized and investigated as green cor-rosion inhibitors of N80 steel in 15% HCl using chemical and electrochemical techniques complemented with field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM) and density functional tight-binding (DFTB) modeling. Results obtained showed that both hydrazones acted as effec-tive mixed-type inhibitors, protecting the N80 steel in 15% HCl at 303 and 333 K. Inhibition efficiencies of 98.5% and 98.0% were obtained at 303 K and optimum concentrations of FHDZ and MHDZ, respectively. The anticorrosion properties of investigated hydrazones toward N80 steel dissolution were also evalu-ated gravimetrically at 333 K, and inhibition efficiencies of 92.3% and 90.5% were obtained in the same order at optimum concentrations. FE-SEM and AFM results proved the formation of a preventive layer on the N80 steel surface against acid corrosion. The adsorption energies computed from DFTB calcula-tions successfully predicted the experimental inhibition performance. We have found strong covalent bond formation between inhibitor molecules and Fe-atoms, which was confirmed by the projected den-sity of states (PDOS). This study provides an experimental and atomic understanding of the corrosion inhibition mechanisms of N80 steel by hydrazone molecules, which could open a new way to develop effective eco-friendly corrosion inhibitors for well acidization. (c) 2021 Elsevier B.V. All rights reserved.