Anticorrosion Effect of Terephthalamide Core: Bis(2-hydroxybenzoic Acid) for Steel in Biogasoline

Biogasoline contributes to environmental protection by reducing the use of crude oil, but it pollutes the environment through corrosion. Many toxicity concerns remain with commonly used anticorrosion additives, prompting the search for environmentally friendly and effective anticorrosion compounds. This study proposes an acylamide chemical (H4TDA) as an effective anticorrosion agent for AS1020 steel in E85 biogasoline. After the immersion test, experimental analyses were performed to evaluate the anticorrosion characteristics (comprising corrosion current density, corrosion rate, corrosion inhibition efficiency, and polarization resistance), samples' surface morphology, and metal contents in the biogasoline. Simulation analyses (consisting of structure elucidation, Fukui index analysis, molecular dynamics at various H4TDA concentrations, and binding energy analysis) have demonstrated that H4TDA is most effective at an appropriate concentration to establish a protective monolayer covering the steel surface, corresponding to 100 ppm in the experiment. At optimum concentration, the sample's surface morphology is most uniform, Raman spectra reveal only H4TDA vibrational modes, and the metal contents in gasoline reach the lowest. The study also showed the influence of H4TDA's structural polarization that modified the steel surface charge and encouraged the generalized Langmuir adsorption.