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 protecting 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-isobutylphenyl)propanehydrazide (FHDZ), bearing ibuprofen moiety were synthesized and investigated as green corrosion 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 effective 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 evaluated 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 calculations 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 density 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.