β-alumina and green H2 production from discarded aluminum foil via a novel refined hydrolysis-calcination pathway process

The escalating generation of multilayer packaging waste presents significant environmental challenges due to their complex laminated structure comprising paperboard, polyethylene, and aluminum foil. This study presents a novel integrated hydrolysis-calcination pathway for complete valorization of Aluminun multilayer pakaging waste, achieving simultaneous production of green hydrogen and β-alumina solid electrolyte. Following hot water separation of the paperboard fraction, the LDPE/aluminum laminate undergoes alkaline hydrolysis, generating hydrogen gas with a yield of 97.5% (215 mL from 5.9 g waste) while preserving intact LDPE film for direct mechanical recycling. Kinetic analysis reveals that increasing NaOH concentration reduces activation energy from 26.2 kJ/mol (1M) to 12.7 kJ/mol (4M). The resulting sodium aluminate solution is transformed into pure β-alumina (NaAl₁₁O₁₇) phase via controlled precipitation at pH 9 and calcination at 1000°C. Comprehensive characterization (XRD, SEM-EDS, FTIR, TGA, photoluminescence) confirms good material quality suitable for advanced energy storage applications. This zero-waste process exemplifies circular economy principles, converting challenging multilayer packaging into four high-value products: renewable hydrogen fuel, advanced battery electrolyte material, recycled polymers, and cellulosic feedstock.