An alternative solution to the problem of aluminum–plastic multilayer waste utilization was suggested. The process can be used for hydrogen generation and layer separation. Three different sorts of aluminum–plastic sandwich materials were treated with an alkali solution. In the temperature range of 50–70 °C, for tablet blisters of polyvinylchloride and aluminum (14.8 wt.%), the latter thoroughly reacted in 15–30 min. For sheets of paper, polyethylene, and aluminum (20 wt.%), full hydrogen ‘recovery’ from reacted aluminum component took 3–8 min. From the lids of polyethylene terephthalate, aluminum (60 wt.%), and painted polyethylene with perforations, the aluminum was consumed after 45–105 min. The effect of perforations was the reduction of the process duration from nearly 90 min for the lids with no perforations to nearly 45 min for the perforated ones (at 70 °C). Perforations provided better contact between the aluminum foil, isolated between the plastic layers, and the alkali solution. Hydrogen bubbles originating near those perforations provided foil separation from the upper painted plastic layer by creating gas gaps between them. The remaining components of the composite multilayer materials were separated and ready for further recycling.

Ball-milled hydroreactive powders of Mg-Al scrap with 20 wt.% additive (Wood’s alloy, KCl, and their mixture) and with no additives were manufactured. Their hydrogen yields and reaction rates in a 3.5 wt.% NaCl aqueous solution at 15–35 °C were compared. In the beginning of the reaction, samples with KCl (20 wt.%) and Wood’s alloy (10 wt.%) with KCl (10 wt.%) provided the highest and second-highest reaction rates, respectively. However, their hydrogen yields after 4 h were correspondingly the lowest and second-lowest percentages—(45.6 ± 4.4)% and (56.0 ± 1.2)% at 35 °C. At the same temperature, samples with 20 wt.% Wood’s alloy and with no additives demonstrated the highest hydrogen yields of (73.5 ± 10.0)% and (70.6 ± 2.5)%, correspondingly, while their respective maximum reaction rates were the lowest and second-lowest. The variations in reaction kinetics for the powders can be explained by the difference in their particle sizes (apparently affecting specific surface area), the crystal lattice defects accumulated during ball milling, favoring pitting corrosion, the morphology of the solid reaction product covering the particles, and the contradicting effects from the potential formation of reaction-enhancing microgalvanic cells intended to induce anodic dissolution of Mg in conductive media and reaction-hindering crystal-grain-screening compounds of the alloy and metal scrap components.

The effect of thermal treatment of aluminum core-shell particles on their oxidation kinetics in water for hydrogen production was investigated. The samples were obtained by dividing dried aluminum powder, partially oxidized by distilled water, into eight portions, which were thermally treated at temperatures of 120, 200, 300, 400, 450, 500, 550 and 600 °C. Alumina shell cracking at 500–600 °C enhances hydrogen generation due to uncovering of the aluminum cores, while sharp thickening of the protective oxide film on the uncovered aluminum surfaces at 550–600 °C significantly reduces reactivity of the core-shell particles. For these reasons, after reaction with distilled water at 90 °C for two hours, the highest hydrogen yield (11.59 ± 1.20)% was obtained for the sample thermally treated at 500 °C , while the yield for aluminum core-shell powder without heat treatment was only (5.46 ± 0.13)%. Another set of experiments employed multiple consecutive cycles of alternating oxidation by water and thermal treatment at 500 °C of the same powder sample. As predicted, the hydrogen yield gradually decreased with each subsequent experiment. The series of six cycles resulted in a total hydrogen yield of 53.46%.