Phosphor-ing
Hazard to Others
Posts: 244
Registered: 31-5-2006
Location: Deep South, USA
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Mood: Inquisitive
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Silica dust
There is a white/grey powder on the floor of a new warehouse we are converting. No work has been done inside yet. I think this powder is silica dust
left over from the original build (saw cuts in the concrete floor). Is there a test I can do at to determine if silica is present/how much of the dust
is silica? I don’t have analytical instruments. I do have glassware and access to basic chemicals.
I am not trying to do an analysis for the job/OSHA requirements. I just want to do a little chemistry and learn a new test or two.
"The nine most terrifying words in the English language are: 'I'm from the government and I'm here to help.'" -Ronald Reagan
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Rainwater
National Hazard
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SiO2 is basicly glass. Concrete is a complex mixture with lots of carbonates and oxides.
Most the components react with mineral acids.
If you dry and weigh a sample, aqua regia should remove almost everything but the silica.
A safer method would be HCl + hydrogen peroxide
This mixture is almost as powerful as aqua regia and will disolive most metals
If its new concrete, unsealed, then the slab will 'dust' CaCO3 for a few months. Apply a sealent or keep it mopped/wet.
Concrete dust is dangerous because it has to be coughed up, your body has no other way to get rid of it.
All this goes without saying anything about the dangers of exposing a mystery dust to strong acids and oxidizers. Stay safe
"You can't do that" - challenge accepted
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Bedlasky
International Hazard
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Silica dissolves in molten NaOH. You can then dissolve sodium silicate in the water and precipitate hydrated SiO2 by adding HCl. Or slightly better
test is when you add molybdate in to the sodium silicate solution before you add HCl. Molybdate forms with silicate yellow complex in acidic solution
(silicomolybdate [SiMo12O40]4-). Ammonium and potassium silicomolybdates are insoluble, so you can precipitate them.
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Phosphor-ing
Hazard to Others
Posts: 244
Registered: 31-5-2006
Location: Deep South, USA
Member Is Offline
Mood: Inquisitive
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I will get a sample tomorrow while I am at work. The HCl/peroxide seems doable.
I read an article about testing for it, but they used infrared spectroscopy. They mentioned the “pyrophosphoric acid method”. I found an article
about that but it’s in Chinese.
https://www.jeom.org/en/article/doi/10.13213/j.cnki.jeom.201...
Anyone know anything about the pyrophosphoric method? Or could possibly translate what I assume to be Chinese? I don’t have access to a computer
right now so translation is unfortunately outside my abilities.
"The nine most terrifying words in the English language are: 'I'm from the government and I'm here to help.'" -Ronald Reagan
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