GrayGhost- - 12-12-2018 at 16:30
Hi , I have a question , my ammonium hydroxide is 5% approx, and need concentrate this solution, my idea is add Calcium Oxide, this take water and
concentration goes up or ammonia gas evolve?
Calcium hydroxide formed is practly insoluble.
Thanks
j_sum1 - 12-12-2018 at 16:43
Any strong base will push the equilibrium and drive off NH3 gas. Calcium oxide would not be my first choice since it will form the hydroxide with
water anyway.
Once you have a stream of ammonia gas you can then reabsorb into water to create the solution you want. Be conscious of your setup since NH3 absorbs
rapidly into water and this makes the system very sensitive to pressure and temperature fluctuations. There is a current thread on this topic. https://www.sciencemadness.org/whisper/viewthread.php?tid=10...
My instinct would be to keep your 5% solution as is and if you need something stronger make it from ammonium sulfate and sodium hydroxide. I think
this would be easier than trying to concentrate from a relatively dilute starting material.
AJKOER - 15-12-2018 at 15:04
If you are working with store purchased ammonia, a word of advice that agrees with this comment by Dosey at https://www.fishlore.com/aquariumfishforum/threads/where-to-... :
"You are looking for a product that contains 3 ingredients. Ammonia, water and surfactants. The ammonias that you want to stay away from contain other
ingredients such as scents and other detergents."
I added a good amount of MgSO4ยท7H2O (as Epsom salt) to a lemon scented ammonia product (pH check was consistent with around a 3% solution), expecting
Mg(OH)2 and (NH4)2SO4.
However, there remained a strong scent and a pH of 8.9!
Avoid such products.
[Edited on 15-12-2018 by AJKOER]