Piroxicam: 2-hydroxypropyl-β-cyclodextrin complex as corrosion inhibitor for the aluminum anode in extremely alkaline-based primary batteries

The corrosion inhibitive capabilities of an aluminum anode in 6 M KOH solution at 50 degrees C with single piroxicam: 2-hydroxypropyl-beta-cyclodextrin molecular inclusion complex (PIR: HP-beta-CD) and mixed PIR: HP-beta-CD + Na2SnO3 additives are investigated using hydrogen gas collection, weight loss measurement, electrochemical tests, infrared spectra, and scanning electron microscopy (FESEM). The results indicate that the corrosion inhibition efficiency of PIR: HP-beta-CD additive is increased to 10 ppm concentration (33%). The PIR: HP-beta-CD adsorbs on the aluminum surface and impedes the accessibility of water to the surface. On the other hand, using only 0.002 M Na2SnO3 reduced aluminum's anodic dissolution and did not provide sufficient efficiency in inhibiting hydrogen evolution. However, adding 10 PIR: HP-beta-CD to KOH solution containing 0.002 M Na2SnO3 has created a synergistic effect in corrosion inhibition. The highest electrochemical activity, the lowest hydrogen evolution rate (4.48 ml cm(-2) s(-1)), the highest inhibition efficiency (81.14%), and the highest capacity are attained in the 6 M KOH solution with the mixed additives. Indeed, the 10 ppm PIR: HP-beta-CD + 0.002 M Na2SnO3 additives could be recommended as an excellent corrosion inhibitor in extremely alkaline electrolytes for the aluminum anode at high current densities.