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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 MobiusHorizons on Saturday May 20, 2023 @02:26AM (#36009804)
Note that it is Aluminum Oxide not elemental aluminum. Aluminum Oxide is not very reactive, and completely insoluble in water. if you were concerned about it, pass your treated water through a coffee filter after removing the powder magnetically. I'd be much more concerned about what this process can't remove from water though, things like heavy metals or other chemical contaminants.
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Re:Nontoxic powder uses sunlight to quickly disinfect contam... by prox on Saturday May 20, 2023 @04:49AM (#36010346)
Is aluminum magnetic? Didn’t think so?
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Re:Nontoxic powder uses sunlight to quickly disinfect contam... by dspillett on Saturday May 20, 2023 @04:58AM (#36010380)
No, that is why it might still there to remove with a coffee filter, after removing the powder magnetically, I assume.
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Re:Nontoxic powder uses sunlight to quickly disinfect contam... by MobiusHorizons on Saturday May 20, 2023 @12:20PM (#36013206)
> The powder consists of nano-size flakes of aluminum oxide, molybdenum sulfide, copper, and iron oxide

Aluminum oxide is not magnetic, but the iron oxide (presumably bonded to the other ingredients) is magnetic.

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Re:Nontoxic powder uses sunlight to quickly disinfect contam... by culi on Saturday May 20, 2023 @04:11PM (#36015123)
The original paper specifies in the abstraction:

> discrete nanoflakes of (Al2O3@v-MoS2)/Cu/Fe3O4

https://www.nature.com/articles/s44221-023-00079-4

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Re:Nontoxic powder uses sunlight to quickly disinfect contam... by shirleyquirk on Saturday May 20, 2023 @07:47AM (#36011074)
Metallic aluminium is insanely reactive and any Aluminium exposure will always be in the form of oxides or hydroxides. It's disingenuous to suggest that it is inert in this form, especially given that the point of the exercise is active, complex, catalysed photochemistry.
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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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