Waste-to-hydrogen production: Recycling aluminium dross in alkali solutions

The valorisation of aluminium dross for hydrogen production offers a sustainable waste-to-energy pathway. This study examines hydrogen evolution from aluminium dross in aqueous NaOH and KOH (0.25–1.0 M) at 40–70 °C, measuring it as a function of time and using 3D contour mapping to determine initial rates and cumulative yields. Hydrogen evolution rises with alkali concentration and temperature; NaOH produces higher rates and volumes at lower conditions, while KOH exhibits steadier temperature-driven increases. The kinetic study reveals that the Avrami-Erofeyev model provides the best fit to the experimental data, showing excellent linearity (R2 = 0.95–0.99). The calculated reaction orders (n = 0.88–1.23) indicate a near first-order behaviour consistent with nucleation-growth mechanisms. Arrhenius analysis gives activation energies of 63.07 kJ/mol (0.5 M NaOH) and 73.62 kJ/mol (0.5 M KOH), highlighting differing mechanistic regimes. This work frames dross recycling as a strategy to convert hazardous residue into low-carbon fuel, advocating integration of such benign hydrogen-generation routes into industrial design and policy to close material loops and enhance resilience.