Sciencemadness Discussion Board

little help needed

Aqua_Fortis_100% - 21-6-2007 at 04:35

Hi all

i'm bored and tired of my household common crappy 2-3% ammonia solution, so i'm building right now a little NH3 "absorption tower" to make these thing more "powerfull" ..this tower was made from a large PVC pipe and some coke disposable glass bottles as gas generators and all highly improvised(the calculated volume which this can stang is over 5 L by time :D )..i'm aware from suckback problem, so i'm planning to use along the generators some aquarium pumps to avoid this and get more yield in absorption(instead of using inverted funnels or such and putting the hose in the bottom of the tower).. i dont have any drawings or photos right now , but i will try later to explain better..

the problem i encountered is from the materials of the "absorpition tower".. i've used to sealants common PVA/latex white glue , epoxy resin , and calcium sulphate (plaster of paris).. along to PVC and a old plastic tap attached to bottom of the pipe(i dont know what kind of plastic this was made)..

are these materials resistants enough to strong NH4OH ? if no what i should use instead?

BTW, has anyone documents of corrosive action of ammonia in plastics, etc?

thanks a lot.

Aqua_Fortis_100% - 21-6-2007 at 04:40

sorry by double post but: my generator is comprised of calcium hydroxide and ammonium sulphate... any technical problems in using this? (i dont have any other source of cheap ammonium salts) and if this can affect greatly in corrosiveness of materials used (?)

thanks again

not_important - 21-6-2007 at 05:55

Quote:
Originally posted by Aqua_Fortis_100%

the problem i encountered is from the materials of the "absorpition tower".. i've used to sealants common PVA/latex white glue , epoxy resin , and calcium sulphate (plaster of paris).. along to PVC and a old plastic tap attached to bottom of the pipe(i dont know what kind of plastic this was made)..

thanks a lot.


'white glue' or PVA glue softens when damp, so it's not very good around water.

Calcium sulfate is slightly soluble in water, more so in solutions of ammonium salts or ammonia.

Epoxy should hold up, the normal solvent based PVC cements will work too.

Do a Web search on "resistance ammonia plastics" and you'll find plenty of charts like this one:

http://www.eldonjames.com/html/chemical.html

Don't use copper or copper alloys around ammonia, it's like ferrous metals around HCl fumes.

The problem with lime and ammonium sulfate is the low solubility of the calcium sulfate and its tendency to become a lump. That tends to keep all the lime from reacting, or at least reacting quickly.

I used a plastic bucket that fit snugly into a metal bucket as the generator, heating that in a larger drum of water. I stuck a heavy duty paint stirrer through the lid of the plastic bucket to keep the contents mixed.

The buckets had a slight taper, so the calcium sulfate was fairly easy to remove when done. It still was a hassle, so I went to making crude lye from the lime and soda ash, using an excess of lime. I boiled the lye solution down some, but not a lot, and let it settle in a closed bucket after that before using. I went through this because at the time and location lye was difficult to find and purchases seemed to be monitored by the local constabulary; ammonia was only available as liter bottles of the sudsy variety, and I wasn't set up to be a business to order any. But I could get 20 kilo sacks of ammonium sulfate or phosphate, as well as soda ash, without standing out.

Aqua_Fortis_100% - 21-6-2007 at 07:29

THANKS!!!!!!!
Quote:
originally posted by not_important :
'white glue' or PVA glue softens when damp, so it's not very good around water.


AHHH :( i forgot this basic thing...

thanks also for the advise on calcium sulphate and ammonia.. i've used this because is most cheap i've just now on hand.. the epoxy as you said is great for the purpose, but is highly cost expensive (at least where i live)... in theory i would merely put a lid on the bottom..but my pipe is a single disposed take from the trash and therefore i've washed and made thousands of modifications to stay appropriate..


solvent based PVC cements is a very good idea!!!
i really like. and i will try first with my materials and then post again here..
thanks!!



[Edited on 21-6-2007 by Aqua_Fortis_100%]