Investigation of a novel hexafunctional epoxy resin as an anti-corrosion agent for carbon steel in an HCl environment

This new investigation focused on the creation of a novel hexafunctional epoxy resin by synthesizing a two-tier aromatic radical matrix containing bonds such as C = C, C–N, C–C, and P = O. The initial step involved obtaining the precursor molecule for the epoxy matrix, which was subsequently functionalized with epichlorohydrin. The resin was meticulously characterized using Fourier transform infrared and nuclear magnetic resonance spectroscopy, which revealed its structure at a microscopic level. Concurrently, the viscosity parameters were analyzed to have a better understanding of the resin's flow properties. Epoxy resin is widely recognized as a superior protective agent due to its distinct electron donor and acceptor sites. The properties of phosphoric ester hexaglycidyl para-amino phenol resin (HGPAPEP) were carefully studied to determine its potential as a protective agent. At 298 K, Carbon steel was immersed in 1.0 M of hydrochloric acid at 298 K. Surface inspection was carried out using electrochemical techniques and scanning electron microscopy/energy dispersive spectroscopy. The data show that HGPAPEP has remarkable corrosion-inhibiting characteristics in hydrochloric acid. Potentiodynamic polarization and electrochemical impedance spectroscopy revealed an excellent 95.90% efficiency at 10^–3 M. Isothermal adsorption experiments established that our protective compound follows the Langmuir adsorption model. The Gibbs adsorption free energy (ΔG_ads) value of −44.24 kJ/mol suggests that the protective agent molecules form a chemical bond with the electrode surface, resulting in excellent corrosion protection. A theoretical study reinforced this surface analysis, verifying our experimental results.