Surface and Interfacial Performance of Meldrum's Acid Derivatives for Aluminium Corrosion Inhibition in Alkaline Aluminium–Air Systems: Experimental Evaluation and Data–Driven Optimisation

Aluminium–air batteries are low cost and have a high theoretical capacity, but the discharge efficiency and metal utilisation are restricted by the self‐corrosion of aluminium‐anode in alkaline electrolyte. In this study, two Meldrum's acid derivatives, thiophenecarboxaldehyde Meldrum's acid (THMA) and p ‐tolualdehyde Meldrum's acid (TOMA), were synthesised and evaluated as corrosion inhibitors for aluminium in 3 M KOH solution. The structural compounds were validated using ATR‐FTIR, NMR and elemental analysis. At room temperature, after 6 h of immersion in 3 M KOH and various concentrations of inhibitors, the results revealed that inhibition efficiency increased with increasing inhibitor concentration, with maximum efficiency of 65.77% (THMA) and 63.99% (TOMA) at 2.5 mM. Weight‐loss measurements were conducted in triplicate ( n = 3), and the corrosion rate was reported as 0.00588 ± 0.00053 g cm −2 h −1 (TOMA) and 0.00559 ± 0.00016 (THMA; mean ± SD). THMA and TOMA were best described by the Freundlich and Langmuir isotherms, respectively, while Gibbs free‐energy values suggested mixed physical and chemical adsorption on the aluminium surface. Surface analyses demonstrated the formation of a protective layer that significantly reduced aluminium surface damage in alkaline media. RSM optimisation revealed optimal conditions at an inhibitor concentration of 0.51 mM, KOH concentration of 0.61 M and immersion time of 2.81 h, yielding predicted inhibition efficiencies of 81.90% (THMA) and 74.00% (TOMA). Pearson correlation analysis showed that immersion time is the most influential factor affecting inhibition efficiency, while machine learning modelling indicated that the random forest algorithm provided the most reliable prediction performance.