Expired dapagliflozin as a promising corrosion inhibitor for copper in 1.0 M nitric acid: experimental and computational validation

The efficacy of expired dapagliflozin (DAP) as a sustainable and cost-effective corrosion inhibitor for copper (Cu) in 1.0 M HNO₃ was investigated using a combination of experimental and theoretical approaches. Chemical and electrochemical methods were applied to assess the anticorrosion efficacy over a range of concentrations and temperatures. The results demonstrated that the anticorrosion efficiency of expired DAP is significant and increases with increasing inhibitor concentration but decreases as the temperature rises. This indicates that the inhibition process is primarily governed by the physical adsorption of expired DAP molecules onto the Cu surface. However, the observed change in βₐ suggests that the adsorption is not purely physical in nature but rather involves a mixed physical and chemical adsorption mechanism. Potentiodynamic polarization (PDP) results indicate that expired DAP functions as a mixed-type inhibitor, effectively suppressing both anodic metal dissolution and cathodic reduction reactions. Moreover, a pronounced positive shift in the pitting potential (Eₚiₜₜ) was observed, indicating a significant enhancement in resistance to pitting corrosion. The thermodynamic parameters associated with both activation and adsorption processes were evaluated and analyzed, offering deeper insight into the corrosion inhibition mechanism. The inhibition effect of expired DAP is attributed to the formation of a stable complex between DAP molecules and Cu²⁺ ions adsorbed on the metal surface. Conductometric titration indicates a 1:1 stoichiometric ratio for the Cu²⁺–DAP complex. The adsorption of this complex reduces the corrosion rate and enhances inhibition efficiency. Theoretical calculations further confirm that DAP exhibits a strong tendency to absorb onto the Cu surface, reflecting its remarkable inhibitory potential. Good agreement between the theoretical predictions and the experimental results highlights the consistency of the applied approaches and strengthens confidence in the reported results.