A Novel Naphthalimide Derivative as a Carbon Steel Corrosion Inhibitor: Synthesis and Performance Evaluation

Corrosion of carbon steel in acidic media remains a major concern in industrial applications, often resulting in material degradation and economic loss. In this study, a novel naphthalimide-based corrosion inhibitor, 6-(benzylamino)-2-(2-hydroxyethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione(BA-HEBQ), was synthesized and evaluated for the protection of Q235 carbon steel in 1 M HCl solution. BA-HEBQ exhibited excellent inhibition performance, achieving an inhibition efficiency of 91.97% at a low concentration of 30 mg·L–1. Electrochemical method and weight loss method demonstrated that the inhibitor effectively suppressed the corrosion process through adsorption on the steel surface. Density functional theory calculations indicated that the introduction of benzylamino and hydroxyethyl groups enhanced the adsorption strength and electron-donating ability of the inhibitor. The findings confirmed that introducing two functional groups was a promising method to improve the effect of naphthalimide derived corrosion inhibitors. This work provides theoretical and practical directions for the development of other highly efficient naphthalimide inhibitors.