Discovering the Corrosion Resistance of Mild Steel Using Chromone Derivatives As Corrosion Inhibitors to Reduce the Environmental Impacts

Despite the wealth of findings already available in the corrosion field, exploring the adsorption process of organic inhibitors onto steel surfaces remains an area of active research. This pursuit is particularly relevant in the context of sustainable development, where the use of environmentally friendly inhibitors is encouraged to minimize the environmental impact of industrial processes. In this work, two novel organic compounds, 4-oxo-2-(prop-2-yn-1-ylamino)-4H-chromene-3-carbaldehyde (OPC) and 2-(benzylamino)-4-oxo-4H-chromene-3-carbaldehyde (BOC), were synthesized and evaluated as corrosion inhibitors for mild steel in 1 M HCl solution. The electrochemical outcomes of OPC and BOC revealed the mixed-type characters, protecting anodic and cathodic reactions. In addition, they reached an inhibition efficiency of 97% for OPC and 95% for BOC at the 10−4 M. According to the Langmuir isotherm model, these molecules adsorb onto the steel surface, displacing water molecules and forming an inhibitor layer. This adsorption was confirmed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, as well as by X-ray diffraction and UV–visible molecular analysis. On the other hand, DFTB and DM simulations confirmed the high reactivity of these molecular structures, especially for OPC, which contains triple-bond groups. The theoretical outcomes supply a thoughtful explanation for the inhibition behavior and confirm the experimental findings.