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A comment on Nontoxic powder uses sunlight to quickly disinfect contaminated drinking water. Parent comment

Re:Nontoxic powder uses sunlight to quickly disinfect contam... by syntaxing on Saturday May 20, 2023 @09:40AM (#36011858)
Not a chemist but a MechE. How is aluminum insanely reactive? Aluminum oxide is significantly less prevalent than iron oxide (aka rust). Even on a sheet metal part, you might get a couple microns worth of aluminum oxide. Hell, we purposely anodize it so we get more aluminum oxide.
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Re:Nontoxic powder uses sunlight to quickly disinfect contam... by BostonEnginerd on Saturday May 20, 2023 @10:05AM (#36012027)
Aluminum is extremely reactive. It self-passivates with Aluminum oxide very quickly. The difference between rust and AlO3 is that the AlO3 adheres well to the base metal and doesn't flake off like rust does.
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Re:Nontoxic powder uses sunlight to quickly disinfect contam... by sclarisse on Saturday May 20, 2023 @10:20AM (#36012139)
You anodize it to get more because the raw material is so reactive that it forms a thin layer of oxide more or less instantly. That keeps more oxygen out, but it’s too thin and can be easily scratched.
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