Development and anti-corrosion performance of hyperbranched polyglycerol-decorated Fe3O4@SiO2 on mild steel in 1.0 M HCl

Abstract

In this work, Fe3O4 magnetic nanoparticles (MNPs) and Fe3O4@SiO2 modified with hyperbranched polyglycerol (HPG) were synthesized, characterized, and their corrosion inhibition performance on mild steel in 1.0 M hydrochloric acid (HCl) solution was discussed. The developed nanoparticles can easily be recovered with magnet from the solution, are nontoxic, very active because of being rich in hydroxyl groups, and can easily be dispersed in the matrix. Microstructure and chemistry of nanoparticles were studied by Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Atomic force microscopy (AFM) together with electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and linear polarization resistance (LPR) confirmed improvements in the inhibition properties by modification of Fe3O4 nanoparticles with SiO2/HPG layer. Analyses on weight loss and electrochemical properties confirmed adsorption of inhibitor as a protective layer on the surface of steel. The inhibition efficiency of nanoparticles was enhanced as the concentration of inhibitors increased. The maximum inhibition efficiency for Fe3O4 (MNPs) and Fe3O4@SiO2/HPG at 300 ppm concentration has been obtained 78.07% and 82.96% respectively. AFM confirmed that attachment of –OH groups to the surface of MNPs in terms of roughness at the carbon steel surface so that an increased from 54.5 nm for blank sample to 95.4 nm for sample containing Fe3O4@SiO2, and also to 137.1 nm for the sample containing Fe3O4@SiO2/HPG nanoparticles was meaningful. Analysis of adsorption isotherms revealed that adsorption of inhibitors on metal surface follows Langmuir isotherm. Additionally, to get detailed electronic/atomic-level findings regarding the HPG interactions over the metal substrate, theoretical investigations applying Monte Carlo (MC), molecular dynamics (MD) and density functional theory (DFT) methods were conducted. The results extracted from these approaches affirmed the HPG adsorption on the metallic adsorbent.