Sciencemadness Discussion Board

ammonium chloride purification

nelsonB - 2-3-2017 at 11:44

hi
i got a solution of ammonium chloride
the solution was acidic from hydrochloric Acid and some metal object have been used to manipulate the solution and its gained some greenish color,

any idea about how should it be purified.

i am not sure about recrystalisation.

Sulaiman - 2-3-2017 at 12:24

I don't know if it helps but ammonium chloride sublimes at 338oC

you may be able to boil to dryness ,then hopefuly only the ammonium chloride sublimes.

JJay - 2-3-2017 at 13:27

You might try reacting it with a strong base and bubbling the resulting ammonia gas into water and then neutralizing it with hydrochloric acid. You might have to heat the solution to evolve much ammonia gas. Note that this can be pretty smelly.

There's also recrystallization.

volkchemie - 2-3-2017 at 16:19

Quote: Originally posted by Sulaiman  
I don't know if it helps but ammonium chloride sublimes at 338oC

you may be able to boil to dryness ,then hopefuly only the ammonium chloride sublimes.


Ammonium chloride also decomposes at the sublimation temperature leaving you with ammonia gas and hydrogen chloride gas. This reacts to reform ammonium chloride again but you might lose a bit.

j_sum1 - 2-3-2017 at 16:38

Quote: Originally posted by nelsonB  
hi
i got a solution of ammonium chloride
the solution was acidic from hydrochloric Acid and some metal object have been used to manipulate the solution and its gained some greenish color,

any idea about how should it be purified.

i am not sure about recrystalisation.


In all honesty, I would start again. And this time use a glass rod for stirring. I mean the exercise of purification might be interesting but probably not at all worth it in practice.

violet sin - 2-3-2017 at 18:01

Why not try to plate the metals out using graphite electrodes? my first though,.. Ya don't do that! Nitrogen trichloride can result or chloramines. Electrolysis of ammonium chloride, https://www.google.com/patents/US2209681, mentions a way to make NH3 or Cl2 or both. While avoiding the previous issues as well as N2 loss.

"The underlying principle on which the invention is based resides in the electrolysis of aqueous ammonium chloride solutions in the presence of chlorides of alkali metal and alkaline earths which we find inhibit the production of nitrogen trichloride, and such products as nitrogen and chloramines. "

AJKOER - 5-3-2017 at 13:43

Remake NH4Cl.

Household ingredients path: To 1 mole of Epsom salt (MgSO4) add water and 2 moles of NaCl. Then, dissolve salts and freeze out the Na2SO4 hydrate.

To the remaining aqueous MgCl2, add 1 mole of NH3 gas (or pure aqueous ammonia) and let the Mg(OH)2 white precipitate settle (or filter), leaving aqueous NH4Cl. Further additions of NH3 should not produce any cloudiness in the solution. I won'r mention the number of times I have to add more aqueous ammonia, quite annoying, so employ an excess of ammonia.

If a slight excess of MgSO4 was employed, you will have an impurity of (NH4)2SO4, which can be removed by adding Ca(OH)2 and separating out the CaSO4 (good luck). No Ca(OH)2 available, use NaOH, Na2CO3 or NaHCO3 and freeze out the Na2SO4. However, there is now a possible sodium impurity with too much NaOH, .etc, which is the same position if one started with excess NaCl. To remove the excess NaCl, dry the NH4Cl and sublimate to collect a cloud of NH4Cl particles.

[Edited on 6-3-2017 by AJKOER]

macckone - 6-3-2017 at 00:04

Sodium Chloride and Ammonia Solution are mixed,
then carbon dioxide is bubbled through the solution.
Sodium bicarbonate precipitates.

Aka the solvay process.
The solution will contain sodium and ammonium ions
as well as chloride and carbonate ions. The ammonium
chloride is relatively easy to isolate from this mix.

From ammonium sulfate you can also make the chloride
by mixing calcium chloride. calcium sulfate will precipitate.
ammonium sulfate and calcium chloride are easy to obtain.

Panache - 9-3-2017 at 01:55

Quote: Originally posted by AJKOER  
Remake NH4Cl.

Household ingredients path: To 1 mole of Epsom salt (MgSO4) add water and 2 moles of NaCl. Then, dissolve salts and freeze out the Na2SO4 hydrate.

To the remaining aqueous MgCl2, add 1 mole of NH3 gas (or pure aqueous ammonia) and let the Mg(OH)2 white precipitate settle (or filter), leaving aqueous NH4Cl. Further additions of NH3 should not produce any cloudiness in the solution. I won'r mention the number of times I have to add more aqueous ammonia, quite annoying, so employ an excess of ammonia.

If a slight excess of MgSO4 was employed, you will have an impurity of (NH4)2SO4, which can be removed by adding Ca(OH)2 and separating out the CaSO4 (good luck). No Ca(OH)2 available, use NaOH, Na2CO3 or NaHCO3 and freeze out the Na2SO4. However, there is now a possible sodium impurity with too much NaOH, .etc, which is the same position if one started with excess NaCl. To remove the excess NaCl, dry the NH4Cl and sublimate to collect a cloud of NH4Cl particles.

[Edited on 6-3-2017 by AJKOER]


Are you fucking serious Lol?
Mix hcl and an ammonia solution until either is neutralised, boil off water.

AJKOER - 12-3-2017 at 13:33

Panache:

What I described is an actual path I used to prepare MgCl2, then NH4Cl, from cheap grocery store available chemicals (namely, food grade MgSO4, NaCl and ammonia water heated to yield pure NH3 gas).

What some may consider crazy is producing an inexpensive product from more valuable, and likely also, more costly pure reagents.

If you are in a warmer climate, I would think HCl (as a pool chemical to add to higher strength NaOCl) may be more available. Locally for me, even battery acid seems to have vanished. I especially don't like being interrogated when I go into hardware (or larger) store having to explain why I need 'X'.

Tsjerk - 13-3-2017 at 00:59

In what country are you AJOEKER? In the EU at least ammonia and hydrochloric acid are dirt cheap and available without any mention worthy impurities.

For the goal of making ammonium chloride ammonia and hydrochloric acid are by far the easiest and cleanest way to get there.

PirateDocBrown - 13-3-2017 at 02:17

Although Ajoeker's path would work, given that Na2SO4 is much less soluble at low temp than the other salts, the NH4OH + HCl route works far better. But then, he might not have access to hardware store HCl.

Its primary virtue is that you don't even have to measure very accurately. Any excess of either reactant will volitilize when heating to remove the water, because both are gases dissolved in water.

There's no refluxing, no filtration, no distillation, no crystallization. Just combine the two reactants and heat to remove water and volatiles. One could do it in a tin can.

[Edited on 3/13/17 by PirateDocBrown]

[Edited on 3/13/17 by PirateDocBrown]

AJKOER - 13-3-2017 at 05:04

Muriatic acid, which is low grade HCl, is not what I would publicly recommend for the preparation of NH4Cl (unless intended for creating a smoke screen).

For example, mixing impure NH4Cl (possibly containing residual transition metals including iron from Muriatic acid, see https://books.google.com/books?id=KXwgAZJBWb0C&pg=RA1-PT... ) and say a nitrite, or electrolysis of a basic NH4Cl solution (a path to in situ NH4NO2, which has been reported as normally prone to detonation in more concentrated alkaline solutions, see http://www.sciencemadness.org/talk/viewthread.php?tid=68615#... ), or for general use in energetic materials preparation, is asking for a very big surprise.

Akin to a copper ion impurity in a nitrate, a very bad idea, as it can affect storage life (a redox decomposition), safe handling (meaning keeping your limbs) and more sudden premature major 'events'.

Bottom line, in my opinion, think carefully about employing Muriatic acid as an appropriate or safe substitute for HCl in chemical preparations (apart from making gases like CO2, Cl2, or H2).

Here is a related sample example (other than significant corrosion acceleration noted in 1st source reference above) of the consequences of Fe/Cu impurities in NaCl when it comes to fruit preservation https://books.google.com/books?id=x77Ts_cB5CMC&pg=PA16&a... .

[Edited on 13-3-2017 by AJKOER]

[Edited on 13-3-2017 by AJKOER]

Tsjerk - 13-3-2017 at 06:10

I know you will keep discussing with no end to get your right, muratic acid is perfectly suitable for making ammonium chloride.

Even if your extreme and farfetched examples would happen...Nitrite doesn't exist in highly acidic solutions and copper and iron contaminations are easily visible because of their color. The HCl I buy over the counter is perfectly colorless.

AJKOER - 13-3-2017 at 06:24

Quote: Originally posted by Tsjerk  
I know you will keep discussing with no end to get your right, muratic acid is perfectly suitable for making ammonium chloride.

Even if your extreme and farfetched examples would happen...Nitrite doesn't exist in highly acidic solutions and copper and iron contaminations are easily visible because of their color. The HCl I buy over the counter is perfectly colorless.


I have added some references to highlight a range of issues associated, in general, with adding Fe/Cu impurities to HCl and chloride salt. The presence of oxygen, transition metals fostering possible catalytic Fenton and Fenton-like reactions are not something one should dismiss.

Here is a quote from a new source (http://www.crscientific.com/electrolysis.html ):

"DON'T subject ammonium chloride or ammonium perchlorate solutions to electrolysis. Avoid electrolysis on any solution where aqueous Cl2 or Cl- might be present with aqueous NH3 or NH4+, unless you know PRECISELY what you are doing.
There are a couple different things that could form and cause an explosion, poison you, or both."

where the explosion danger, per my research, is referring to NCl3 (acidic conditions) and NH4NO2 (alkaline) for both explosion and poison danger.

I do agree impure NH4Cl is safe for making smoke screens, but adding to another chemical reaction could be problematic.

I would encourage all to read the references.

[Edited on 13-3-2017 by AJKOER]

Tsjerk - 14-3-2017 at 10:07

There is no significant amount of copper or iron in muratic acid.

unionised - 14-3-2017 at 14:16

I guess that, if the OP waited over a year for the first reply, he may still be here 2 years after that.

Just on the off chance; sublimation and recrystalisation are plausible options.

AJKOER - 14-3-2017 at 15:35

My cited source on impurities for Muriatic acid does state that although specification of iron impurity may indeed be low, nevertheless the acid can apparently be 'easily contaminated' as a consequence of shipping (stainless steel vessels?) introducing an iron impurity. With stainless steel, which has a minimum of 10.5% chromium, yet another transition metal potentially added to the mix.

With respect to testing for ferrous and its significance in natural waters, see "Study of the effects of CO2(g) on the Fe(II)-luminol chemiluminescence system: Application to ultra-trace analysis of Fe(II)" a thesis by Sara Beth Lovitz at http://digitalcommons.colby.edu/cgi/viewcontent.cgi?article=... .

Of special concern with transition metal impurities is the presence of even trace amounts of cobalt (no reference citing this is indeed a contaminant here), which can deceive researchers as to what is actually occurring! For example, a trace of cobalt ions in the presence of HSO5- can produce the powerful sulfate radical anion (see "COBALT/PEROXYMONOSULFATE AND RELATED OXIDIZING REAGENTS FOR WATER TREATMENT" a thesis by Georgios P. Anipsitakis, https://etd.ohiolink.edu/rws_etd/document/get/ucin1130533674... ).

[Edited on 15-3-2017 by AJKOER]

clearly_not_atara - 14-3-2017 at 16:26

C'mon, low hanging fruit people. 99% the metal impurity is iron, so we can reduce it with aluminium. And you're likely done immediately, as aluminium salts will not dissolve except in very strong acids.

Sure maybe you have to remake NH4Cl. But give Al a chance!

unionised: this thread was opened only 2 weeks ago?

[Edited on 15-3-2017 by clearly_not_atara]

AJKOER - 15-3-2017 at 06:09

Quote: Originally posted by clearly_not_atara  
C'mon, low hanging fruit people. 99% the metal impurity is iron, so we can reduce it with aluminium. And you're likely done immediately, as aluminium salts will not dissolve except in very strong acids.

Sure maybe you have to remake NH4Cl. But give Al a chance!

unionised: this thread was opened only 2 weeks ago?

[Edited on 15-3-2017 by clearly_not_atara]


Careful if you try using Aluminum foil as the pure Al source. First, the manufacturers work hard in making their foil as inert as possible. I recall reading about a protective plastic coating to mitigate a fast chemical reaction, for example, with your vinegar dressing from your sandwich. This effort is likely to avoid health concerns associated with Aluminum ions ingestion. This protective layer can quickly be burned off, however, the Aluminum foil itself is an alloy (from 1% to 8% other metals per http://www.madehow.com/Volume-1/Aluminum-Foil.html ) sometimes containing, you guessed it, iron!

Most other Aluminum products are also alloys per my recollection, so perhaps not a perfect solution for all.

[Edited on 15-3-2017 by AJKOER]

Tsjerk - 15-3-2017 at 06:33

There is no plastic on aluminium foil. How do you come up with all these non-sense useless facts and posts? Who on earth is transporting HCl in vessels that are corroded by their cargo?

I have successfully ignored your posts for years by just skipping them, there is usually so little reply to your posts that for the reading of the whole thread it doesn't matter, but somehow I did get annoyed by your post.... I don't know why, probably because they are always lengthy and useless.

AJKOER - 15-3-2017 at 08:27

OK, here is the reference to 'plastic' coating comment, to quote:

"When unsure of whether certain wrappers and packaging are in fact aluminium foil, perform the scrunch test – if the material springs back when scrunched, then it cannot be recycled. Most crisp packets spring back because they are made from plastic film coated in a very thin layer of metal"

Link: http://www.iom3.org/materials-world-magazine/feature/2013/ap...

However, this was not my original source when I researched the annealing of Aluminum foil years ago, it just confirms that such a plastic coating exist and is in use.

One can easily verify, in my opinion, the plastic coating is present as just dipping the Al foil into a flame immediately shows the coating catching on fire.

One cannot believe that aluminum foil is inert and at the same time known the chemistry by which the Al2O3 layers can (and does) breaks down with, for example, acetic acid, permitting a reaction of the reactive metal Aluminum with water to form Al(OH)3 and H2 gas. Annealing of the Aluminum is the secondary plan to protect your sandwich, but the plastic coating is the primary defense against food acids.
---------------------------------------------------

To quote my prior comments and the original source (which is, unfortunately, no longer active) again:

"The oxide on top changes during annealing accompanied by a loss of water leading to a more compact oxide of generally higher resistance."

Also, to quote " Ethylene acrylic acid (EAA) films with 6% acrylic acid were melt coated onto this foil in a laboratory oven at 200°C by continuously laying a molten film on the foil as in slow motion extrusion coating."

However, despite all tempts to protect the foil, there is hope. To quote:

"Even at room temperature, acetic acid can easily pass through a coating infiltrating chemical bonds by advanced attack and leading to adhesion failure."

So by first soaking the Al foil in vinegar, you may prime the Al foil for dissolving, we hope.

Source Link:
http://pffc-online.com/the_place/paper_adhesion_coatings_alu...

While the link no longer functions, its address suggests the source was a manufacturer of specialty coatings.
----------------------------------------------------

Here is another source, providing a paper, "Evaluation of adhesion strength between thin aluminum layer and poly(ethylene terephthalate) substrate by peel tests - A practical approach for the packaging industry", link: http://publica.fraunhofer.de/dokumente/N-217076.html to cite yet another source.
-----------------------------------------------------

With respect to why one would transport HCl in stainless steel, my answer is it may generally be just fine. Please note per my statement above: "The presence of oxygen, transition metals fostering possible catalytic Fenton and Fenton-like reactions...", which mentions the missing element, in my opinion, namely oxygen and more precisely, dissolved oxygen, to start the electrochemical based corrosion reaction. If a transport tank is not full, this leaves air/O2 and the act of transporting could assist in producing dissolved oxygen, which could start the process.

[Edited on 15-3-2017 by AJKOER]

[Edited on 15-3-2017 by AJKOER]

JJay - 15-3-2017 at 21:23

I just made some ammonium chloride. I suspect it's pretty pure, but I was thinking about doing a recrystallization and water actually doesn't look like a fantastic solvent for that... I'd lose almost a third of it.

I used regular Wally World muriatic acid. It isn't very potent, but it does seem to be reasonably pure. I have actually run across muriatic acid that contained iron before; while the actual amount of the impurity was very low, it was sufficient to produce a noticeable green residue when evaporating 100 mL of it. I also once ran across some muriatic acid that was pink... I think it contained some sort of dye.

I'm not really sure what I'm going to do with the ammonium chloride, but anhydrous ammonia looks like fun... for now, the ammonium chloride should look nice next to my collection of other ammonium salts.


[Edited on 16-3-2017 by JJay]