Abstract
Kinetic models were fit to experimental hydrogen production data from a stirred microspherical aluminum corrosion reactor, one model for each of two Al initial conditions prior to immersion in aqueous sodium hydroxide at pH 13.17–13.48: (i) air-dry, and (ii) water-suspended for 0.5–2 h, of which the latter has not been studied. Data fitting was fairly precise (R2>0.97), and results were confirmed by comparison to shrinking core models of the reaction time. Key findings were a low reaction order in hydroxide (0.46 for slurry and 0.55 for dry based reactions), along with relatively lower apparent activation energy and frequency factor for the slurry reactions (60.15, versus 64.75 kJ/mol for initially dry Al, with SE≈2.5kJ/mol), and just a slight effect of Al delivery mode on overall rates. Explanatory rate-limiting mechanisms were hypothesized following a model of a dissolving film over the corroding Al with analysis of diffuse electric double layer charging and transport resistance effects.
Published Version
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