Gudmundur Gunnarsson

In this work, three samples of primary aluminium dross were investigated and compared to construction aluminium waste. The composition was determined, and an evaluation of hydrogen generation via hydrolysis in a low-concentration alkali solution was performed. The composition revealed low to moderate aluminium content and the presence of various crystalline phases; hydrolysis reactions showed hydrogen generation’s direct dependence on the amount of aluminium present, which translated into variation in the volume per sample mass. It was found that the composition played a substantial role in the evolution of hydrogen and its purity, simultaneously indicating a possible opportunity for dross use in hydrogen generation and power production. It was revealed that, in addition to the expected hydrogen, methane was released from some dross samples during the hydrolysis reaction. To compare the reaction kinetics, the reaction rate was obtained using the spherical solid particle shrinking core model and compared with that of construction aluminium waste. Hydrogen generation was compared to that in the known literature, and the dependence on the sample composition was determined.

This study investigates the low-temperature hydrogen plasma treatment approach for the improvement of hydrogen generation through waste aluminum (Al) reactions with water and electricity generation via proton-exchange membrane fuel cell (PEM FC). Waste Al scraps were subjected to ball milling and treated using two different low-temperature plasma regimes: Diode and magnetron-initiated plasma treatment. Hydrolysis experiments were conducted using powders with different treatments, varying molarities, and reaction temperatures to assess hydrogen generation, reaction kinetics, and activation energy. The results indicate that magnetron-initiated plasma treatment significantly enhances the hydrolysis reaction kinetics compared to untreated powders or those treated with diode-generated plasma. Analysis of chemical bonds revealed that magnetron-initiated hydrogen plasma treatment takes advantage by promoting a dual procedure: Surface cleaning and Al nanocluster deposition on top of Al powders. Moreover, it was modeled that such H₂ plasma could penetrate up to 150 Å depth. Meanwhile, electricity generation tests demonstrate that only 0.2 g of treated Al powder can generate approximately 1 V for over 300 s under a constant 2.5 Ω load and 1.5 V for 2700 s with a spinning fan.

In this work various sample of primary aluminum dross were investigated for composition and evaluation of hydrogen generation via hydrolysis in low concentration alkali solution. Composi-tion revealed low to moderate aluminium content and hydrolysis reactions showed low hydrogen generation volumes per sample mass as well as purity, where composition plays substantial role in the hydrogen evolution, yet showing that there is possible place for dross use in hydrogen generation. It was revealed that some dross samples in addition to hydrogen also release methane via hydrolysis. Rection rate was obtained by the shrinking core model, written for spherical solid particles. Sample composition on hydrogen generation volume is compared to known literature.

Sodium metal can be made by electrolysis of molten sodium hydroxide in sodium β″‐alumina membrane electrolysis cells. However, some uncertainty is about the lifetime of the sodium β″‐alumina membranes in contact with molten sodium hydroxide. The main objective of the work described here is to address this uncertainty and to study the corrosion of the membranes in molten sodium hydroxide. Samples of sodium β″‐alumina disk were aged in molten sodium hydroxide for up to 149 days. Mass loss was only 0.15% in the first 108 days, but in the next 41 days mass loss accelerated considerably, or up to 0.33% in 41 days. No change in phase composition of the material was observed in the 149 days. Investigation of aged samples with scanning electron microscope revealed that the molten sodium hydroxide preferably dissolved material at grain boundaries, which most likely resulted in freeing of grains (1–5 μm diameter) from the bulk of the material.