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Author: Subject: Recycling the sulfuric acid.
nelsonB
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[*] posted on 20-3-2019 at 16:14
Recycling the sulfuric acid.


Hi
so since sulfuric acid is a bit expensive, i was wondering after making some ether of we could distillate it to use it again in another batch, or if sulfuric acid decompose too much during the production of ethyl ether.
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Ubya
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[*] posted on 21-3-2019 at 01:23


in ether production sulphuric acud doesn't decompose, distillation should be able to remove any volatiles and maybe oxidize any tars if present. if you use it for the same purpose (for making ether for example) i don't see any problems.
if you want to use it as a reagent or in sensible synthesis a few more purification steps could be needed





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woelen
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[*] posted on 21-3-2019 at 01:39


I used concentraded H2SO4 for all kinds of things, such as making volatile esters, as drying agent for chlorine gas (bubbling the gas through the acid), for concentrating nitric acid.
After use, I heat the acid to quite high temperatures (appr. 170 C) and then allow the acid to stand until it becomes completely clear (this only is necessary after experiments with organics). The heating assures that no oxidizing voltiles are left in the acid, such as Cl2 or HNO3. This makes it safe to dump all of it in the same bottle. I keep this bottle, it has acid in it which is not really concentrated, but it also is not dilute. I think it is 70% or so by weight.

The clear liquid I keep for all kinds of less sensitive use. This acid is somewhat impure (it is light brown/yellow). I use it for chlorine generators (diluting it with a moderately concentrated table salt solution and then adding TCCA), for non-critical experiments in which I need a dilute acid (e.g. for making H2 with zinc or magnesium or making nitrite esters with solutions of NaNO2 and an alcohol). I also use it for cleaning sometimes, it is fine for removing stains of metal hydroxides, metal phosphates, metal borates or metal carbonates if I get those and they stick to the glass of a test tube or flask.

So, no complicated purification steps are needed, and still, the acid is useful for quite a few things. Don't throw it away.




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