[Archy12345]

For the past few days I have been fixated on the synthesis of ammonium chloride. Specifically with ammonium hydroxide and hydrochloric acid. Something about the clouds is magic to me. Anyway, I have no access to ammonium hydroxide solutions that do not have surfactants. I would like to believe that during crystallization none of these surfactants become absorbed into the crystals of ammonium chloride, but considering the speed at which the crystals form I highly doubt it would be safe to assume.

I would like to try to remove the surfactants from the crystals. I've been thinking about redissolving them and then doing a rinse of the solution in a sep-funnel with chloroform or methylene chloride in an attempt to extract the surfactants. Would this be a viable method if the aqueous solution was acidified to keep the surfactants protonated and keep their ionic qualities down?

Or is there another way that is just escaping me?

I thank you all for your responses.

[curiouscat]

Why do you care much about a tiny bit of surfactants?

[Archy12345]

Why wouldn't I? Half the fun of being a chemist is purity.

[curiouscat]

Why wouldn't I? Half the fun of being a chemist is purity.

Do you have ways to measure purity?

[Archy12345]

Probably gravimetric analysis. Silver nitrate is your friend. xP

[curiouscat]

Probably gravimetric analysis. Silver nitrate is your friend. xP

Interesting. What percent of your  ammonium hydroxide solution is surfactant w/w?

[Archy12345]

Annoyingly enough, the msds sheet for the stuff doesn't even mention the surfactants because I suppose they aren't "hazardous materials." The only way I know that there are surfactants is because of foaming. So I don't know the percentage. And I don't have any way of analyzing that.

This is store-bought ammonia by the way. Nothing fancy.

[curiouscat]

My point was, I'm thinking these surfactants are present at such low concentrations that they are below the detection thresholds of your quantification methods.

Ergo, I doubt it's worth worrying about them. It is hard to reliably remove something you cannot even detect.

[Archy12345]

I can detect in the ppb realm.

[Arkcon]

Ammonium chloride is pretty volatile.  Perhaps you can try sublimation, of a very small sample, to get really high purity.  Basically, just for the fun of it, depending on how accurately you can weigh things for a gravimetric analysis by silver nitrate.  Maybe you can determine before and after, as some sort of assay on the purity of your starting reagents.