Sciencemadness Discussion Board

Concentrating Phosphric acid

Steve_hi - 27-2-2013 at 04:44

Just bought some concrete etching product. I checked the msds which says 15 - 40%. I'd like to concentrate it to about 85% instead of buying it. Its bp is 314°f would simply boiling it on the stove do the trick or is that too simple

Mailinmypocket - 27-2-2013 at 04:52

Quote: Originally posted by Steve_hi  
Just bought some concrete etching product. I checked the msds which says 15 - 40%. I'd like to concentrate it to about 85% instead of buying it. Its bp is 314°f would simply boiling it on the stove do the trick or is that too simple


It looks like slow evaporation or vacuum distillation are the ways to go. I have often heard of it etching glass at high temperatures but this didnt happen to Magpie when vacuum distilled, so I'm not sure anymore. See here:

http://www.sciencemadness.org/talk/viewthread.php?tid=19150

plante1999 - 27-2-2013 at 04:54

Is your product only phosphoric acid? or does it contain nitric acid and other stuff?
If not then I guess you could boil down most of the water, much like sulphuric acid.
I already tried something similar, but I heated too much, and ended with a glass.

Steve_hi - 27-2-2013 at 05:00

The only product listed on the container is phosphoric acid. I originaly bought it to clean out my drip coffee machine which it worked great for. I dont have to wait 20 minutes now for a coffee. I bough it in a gallon container so I'm going to concentrate some of it for lab purposes probably start with one liter so here goes, Ill put it on the stove with the stove hood on.

Thanks for the replies
further search on wicki says a ph of less than 1 ph is about 90% concentration I didn't realize it was already that concentrated so I guess il'l forget boiling it down. It is concrete buster bought at Rona Material if any one is interested it has no coloring or soaping agents in it .

[Edited on 27-2-2013 by Steve_hi]