First-principles investigation on the atomic-level mechanism of acetic acid corrosion on carbon steel

Abstract

Abstract The cathodic reaction mechanism of acetic acid corrosion has been systematically investigated using density functional theory (DFT), and the findings were validated through electrochemical experiments and mechanistic modeling. DFT calculations revealed that the adsorption energy of acetic acid on the Fe(110) surface was consistently positive, indicating that the adsorption process is endothermic, followed by dissociation as the dominant pathway. In contrast, dissociated H⁺ exhibited spontaneous exothermic adsorption on Fe(110), and strong charge transfer between H⁺ and Fe confirmed the thermodynamic preference for H⁺ reduction over direct involvement of acetic acid. Electrochemical analyses further demonstrated that acetic acid enhances corrosion primarily through its buffering effect (supplying additional H⁺ via dissociation). Based on the established buffering effect, a corrosion rate prediction model for acetic acid was optimized, and the optimized model showed improved accuracy, confirming that direct reduction of acetic acid should be ignored.