Abstract
Abstract This study focus on recycling secondary aluminum ash (SAA), a hazardous industrial waste with low reusability and high environmental pollution, into high-performance energy storage materials. The methodology involves a modified low-temperature alkaline melting-acid leaching process: SAA is sintered at 200–600 °C, leached with water/acid, and calcined at 550–1100 °C to synthesize four crystalline Al2O3 phases (γ-, δ-, θ-, α- Al2O3), whose transformation mechanisms are analyzed via XRD, SEM, and FTIR. For the Al/ Al2O3 composite phase change materials (PCMs), metallic aluminum serves as the primary phase change component, and the optimal pressing conditions are determined as 10 MPa pressure and 10-minute holding time, with a mass ratio of Al to Al2O3 optimized at 4:6. Key results show that the Al/δ- Al2O3 PCM exhibits the highest initial heat storage density of 950.33 kJ/kg, retaining 54% (509.82 kJ/kg) after 30 thermal cycles without leakage or structural failure, while all composites have weight loss < 15%. The study highlights that Al2O3 crystal forms influence PCM performance: γ-/δ- Al2O3 enhance heat storage capacity, and α- Al2O3 improves thermal conductivity. This work not only provides an innovative recycling approach for SAA but also develops sustainable high-temperature PCMs, offering environmental benefits through reduced industrial waste and promoting the circular economy, with results aligning closely with conclusions on waste-to-energy conversion and material performance.
NETL
NSTL
Springer Nature