Conversion of aluminum foil to powders that react and burn with water

In the US, the total amount of aluminum scrap and waste, including foil, is outpacing efforts to recycle it into conventional aluminum materials. It would be attractive to develop technologies for converting aluminum foil scrap and waste to useful products and energy carriers. The present paper focuses on the feasibility of converting foil to activated Al powders that chemically split water, releasing hydrogen. As a method for this conversion, high-energy ball milling of Al foil with sodium chloride is investigated, with removing NaCl from the obtained powder by dissolution in cold water or methanol. The powders are characterized using BET specific surface area analysis, laser diffraction particle size analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The obtained micron-sized Al powders readily react with warm (35–80 °C) water. Hydrogen evolution is studied using water displacement, while solid byproducts are examined by X-ray diffraction and thermal analysis. The powders are also mixed with gelled water at various mass ratios and combustion of these mixtures is studied in argon environment. With increasing Al concentration, the combustion front velocity increases despite the decrease in the combustion temperature. The burning rate of the stoichiometric mixture of the activated Al powder with water is comparable with the values reported previously for the mixtures based on nanoscale aluminum, while the content of active Al in the obtained micron-sized powder is significantly higher.