Making Ammonium Thiosulfate from Ammonium Sulphate fertilizer????????

koraks

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Undoubtedly, but the question is if it's very economical in terms of the chemistry involved and the anticipated yields. I think you're better off just either looking for ATS fertilizer (which is ammonium thiosulfate) or use one of the many sodium thiosulfate + ammonium chloride 'tricks' to create a quasi-rapid fixer out of plain hypo. Since ammonium thiosulfate is pretty cheap (so is rapid fixer), I personally don't bother with trying to DIY it; it's just not worth the hassle.

But perhaps our resident chemists would like to chime in.

PS: the route from sulfate to thiosulfate, apart from likely being extremely disadvantageous energetically, would probably involve a number of rather nasty process steps you wouldn't want to perform inside your home.
 
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ruilourosa

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My problem is availability, in portugal ammonium sulfate is quite easy to get... as is sodium thiossulfate but ammonium thiossulfate is not that easy nor cheap...


i use to make sodium thiossulfate + ammonium chloride but i have issues on longevity and number of cm2 i can fix...

thanks!!!
 

fgorga

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Possible is very different from practical as outlined by Koraks.

Thiosulfate is prepared from forms of sulfur that a less oxidized than thiosulfate... either elemental sulfur or sulfite.

Sulfate is more more oxidized than thiosulfate. Thus you would have to begin by reducing the sulfate to sulfite in order to convert it as you suggest. This is not really doable in my estimation.

Once you had sulfite you could make thiosulfate on a small scale. See, for example
Scaling this up to make large amounts is not trivial. Do note that the above method is for the sodium salt, not the ammonium salt. I imagine that the ammonium salt is doable via the same route but I do no know that for a fact.

The bottom line... JUST BUY AMMONIUM THIOSULFATE!
 

fgorga

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Any method for making ammonium thiosulfate on a non industrial scale is not likely to be cheaper than just buying the compound, especially if you do an 'honest' accounting and take into account the cost of energy and the value of your time.
 

koraks

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ruilourosa said:
My problem is availability, in portugal ammonium sulfate is quite easy to get
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I haven't looked into Portugal specifically and I can't read Portuguese, so it's challenging for me to figure out what the local situation is. But I think it may not be as bad as you believe it is. Firstly, there's the possibility of purchasing elsewhere in Europe and just accepting the shipping costs; customs fees & important taxes don't apply as long as you buy from within the EU, which makes a big difference. Secondly, I generally find my chemistry in places you might not expect them in. It takes a lot of Googling, going through online catalogs and a bit of luck to stumble across stuff you need. Finally, I'm sure it's possible to just buy rapid fixer where you live. Honestly, there's very little economic ratio to making a fixer at home unless you live on a nearly deserted island.

If all else fails, you can keep doing the sodium thiosulfate + ammonium chloride thing, but mix it more frequently in smaller quantities so it doesn't go bad, add a source of sulfite to keep the thiosulfate from dying and accept that you don't get the efficiency (in terms of g/m2) that you might get with store-bought chemistry. Left or right, there's always a price to pay. One thing is pretty certain: trying to make your own ammonium thiosulfate is going to be one of the most costly, risky and time-consuming options you have and honestly just isn't realistic for a home user.
 

Anon Ymous

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This! I didn't expect to find ammonium thiosulfate locally, but as I walked in a local farm supplies shop to buy some fertiliser for my orchard, I just "bumped" into it. There was ammonium thiosulfate solution in 1, 5 and 15l containers labeled "Thiosul". The 5l container was about half of what the equivalent amount of rapid fixer would cost me, so I just grabbed it. This solution has a fair bit of ammonium sulfite, which makes it alkaline and keeps quite well. I added some EDTA 4Na, sodium metabisulfite and sulfite that would be needed to make a more or less pH neutral fixer and decanted it in 500ml plastic bottles. It's still ok after some years, without any sign of sulfurisation. A commercial, acidic rapid fixer would likely be dead at this point.

Anyway, if ammonium thiosulfate is unobtainable, the sodium thiosulfate + ammonium chloride method is the best choice, mixed whenever needed and preferably pH neutral-ish. I've done it in the past and didn't notice any longevity issues.
 

Ian Grant

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Ammonium Thiosulphate is available in most countries, usually as a 60% solution, it's used outside the photographic field in agriculture, also gold and silver extraction. But you need to buy it in large IBC containers, or even tanker loads. There's no-one I know of in Europe repackaging in smaller volumes, The Photographers Formulary do, I think, in the US.

The crystals are slightly deliquescent (absorbs water) so it doesn't store well particularly once opened, For this reason it's expensive in crystal form these days. I can buy 500g for £58 ($67) here in the UK. That's uneconomic, it would be a bit less if I still had an account with Sigma Aldrich.

Technically in the EU/UK you need a licence to heat (or burn) Sulphur except for small scale laboratory use, in a certificated fume cupboard.

Ian
 

koraks

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Ian Grant said:
There's no-one I know of in Europe repackaging in smaller volumes
Click to expand...

There's at least 2 sources in my country that I know of because I order with them from time to time. I doubt these are the only ones on the continent. Btw, both offer the stuff as a dry powder.

Ian Grant said:
The crystals are slightly deliquescent (absorbs water)
Click to expand...

It's hygroscopic for sure, which mostly shows up as caking. I haven't had mine deliquesce yet after a few years; ultimately, it will, provided enough moisture is allowed into the container.

The place I ordered it last from currently lists it for € 10 per kg in small quantities and significantly less than that in larger quantities. The more expensive source of the two I use from time to time currently gives a price of a little less than €30 for a 500g tub.

I've done a little rooting around and several firms here offer liquid ATS (essentially just 60% ammonium thiosulfate solution) to farmers. Officially they don't retail to consumers, but I'm sure that if I tried hard enough and placed a few phone calls, I could get some of the stuff for personal use one way or another. It would only make sense to aim for 100l or so this way; otherwise it's not worth the hassle.
 

ags2mikon

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I think that Agfa 304 fixer is your friend. I use it and am fine with it. It does not have the same capacity as rapid fix but if I mix it it often enough I always have fresh fixer. Sodium thiosulfate is used in swimming pool balancing and ammonium chloride is use in goat ranching. I can get both of those locally.
 

Ian Grant

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I'm sure there are some suppliers for reasonable priced small quantities, but they are very difficult to find.

Personally I think the better way to go is find someone, as you're saying, and see if they'll supply what I'd potentially need. The major reason I've not yet done it is I have plenty of Rapid fixer at the moment. I do buy some chemicals in bulk anyway, 25 or 50kg at a time. The main UK supplier of Ammonium Thiosulphate ships in 2000 litre IBCs, or 100 litre and 25 litre polythene drums.

Anon Ymous said:
There are no savings to be made at this price though...
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Particularly when you add shipping as well.

Ian
 

Doremus Scudder

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I'm sure you can get Ilford Rapid Fixer in Portugal. That will likely be your cheapest and most convenient source for an ammonium-thiosulfate based rapid fixer. Bite the bullet and order some from wherever is closest.
 
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ruilourosa

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I have cheap access to sodium thiossulfate... And ammonium chloride. Thats what i use... I also make alcaline fixer with it... I would prefer the speed and the longevity of ammonium thiosulfate fixer....
 
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ruilourosa

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I can buy ready made fixer... Thats not the issue...
 

Rudeofus

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If you want a fast fixer and Ammonium Thiosulfate as raw chemical is too expensive, I can think of three ways:

  1. The by far cheapest and easiest way to get a really good, stable and cheap rapid fixer is ordering color fixer for minilabs, such as this one here. Get a stash of Ammonium Thiocyanate, if you want to pep this fixer up even further. This fixer is far cheaper than any batch of Ammonium Thiosulfate offered to us mere mortals.
  2. The second cheapest method would be mixing a quick fixer, i.e. one from Sodium Thiosulfate and some ammonium salt. I have a formula for a quick fixer based on Sodium Thiosulfate and Ammonium Chloride in the articles section. You can get even better speed, if you mix Sodium Thiosulfate with Sodium Metabisulfite, Ammonia and Acetic Acid. These fixers can get as fast as commercial rapid fixer, but their cxapacity will be weak due to large presence of sodium ions.
  3. The most complex way to obtain Ammonium Thiosulfate would be from Sodium Thiosulfate and Ammonium Tetraborate, the latter of which you can create with Ammonia and Boric Acid. Since Sodium Tetraborate is much less soluble than Ammonium Tetraborate, you should be able to precipitate significant amounts of Sodium Tetraborate, giving you a mix with much more ammonium than sodium ions in solution.The resulting ratio between Sodium And Ammonium will probably depend on temperature. It may work even better, if you can create solid Ammonium Tetraborate first.
 
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ruilourosa

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The issue is economy and availability...
Commercial fixers are costing around 18 euros a liter to make 5 liters... Thats crazy compared to 1 euro or so per liter with sodium thiossulphate plus ammonium chloride. I cannot get ammonium thiossulfate as cheap, its even cheaper to buy hypam...

So, i want an ammonium thiosulfate fixer on the cheap
 

koraks

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ruilourosa said:
Commercial fixers are costing around 18 euros a liter to make 5 liters...
Click to expand...

Have a look at what @Rudeofus said above under option #1. That's €0.45 for 1 liter of working strength fixer excl. shipping. It could even be diluted a little further, bring costs down to the €0.35 ~ €0.40 range.
I'm sure C41 fixer can be obtained even in Portugal.
 

halfaman

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If you have the chance to visit Madrid you can find some nice bargains on fixers.

Fotocasión: FIJADOR KODAK T-MAX 1 L | KODAK | > Laboratorio > Química

FIJADOR KODAK T-MAX 1 L. KODAK. > Laboratorio > Química
www.fotocasion.es
 
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ruilourosa

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Yes, even in Portugal... or i can order it from Listenbourg.... right next to far far away kingdom...

i can buy whatever i want, but since i´m always trying to run (and keep running) a community / school lab with a very tight budget, i have to make cuts, and fixer is the single most expensive thing! that´s the issue...
 

koraks

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I understand you want to minimize costs. I think several realistic options have been offered. I personally couldn't do better than what's already been suggested:
1: Search until you find a cheap source of ammonium thiosulfate locally, possibly only if you buy a somewhat serious quantity at once (more than 25kg)
2: Order ammonium thiosulfate elsewhere in Europe and have it shipped. Again, you might have to accept a large MOQ (minimal order quantity) to make it economically feasible.
3: Use the cheapest source of ready-made fixer available to you, which is nearly certainly C41 fixer.
4: Accept that sodium thiosulfate is very slow and/or has limited capacity and keep using that, whether in combination with an ammonium salt to speed things up, or not.
I guess that about sums it up.

What is NOT feasible is synthesizing the stuff yourself in an economically viable and safe way.
 

Graham51

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From my understanding of chemistry, ammonium thiosulphate fixer is rapid because silver halides form soluble complexes with BOTH thiosulphate and NH3 (ammonia) and hence render those insoluble silver halide crystals soluble. The ammonium ion (NH4+) in solution is in equilibrium with NH3 in aqueous solution depending on pH (high pH pushes the equilibrium towards NH3). The key here is that other ions in solution will make no difference to the solvent effect of NH3 and thiosulphate ions. If you dissolve ammonium "anything", and "anything" thiosulphate together you will end up with something just as effective as a solution of ammonium thiosulphate if the molar concentrations of the NH3 and thiosulphate are equal. I would expect published recipes for rapid fixed have this all worked out.

BUT if you really wanted straight ammonium thiosulphate, you could get close from a solution of ammonium chloride + sodium thiosulphate, which from a chemical point of view, is just a solution containing a bunch of things: NH4+, NH3, Cl-, Na+, and S2032-, which is no different from a solution of ammonium thiosulphate and sodium sodium chloride (if the proportions are correct) Now ammonium thiosulphate is very soluble: 1730g/l according according to Wikipedia, but sodium chloride is only 360g/l, so if you make an equimolar solution and evaporate the water off progressively, the sodium and chloride will meet up and crystallise out, thereby reducing its concentration.

It would work like this: 2 x NH4Cl + Na2S2O3 -> (NH4)2S2O3 + 2 x NaCl (crystallises out)

2 moles of ammonium chloride = 106g; 1 mole of sodium thiosulphate = 250g (for the common pentahydrate form). So roughly in proportion 1:2.5.

I'd be interested to hear of real photography experience though: does pure ammonium thiosulphate work differently from ammonium chloride + sodium thiosulphate?

PS Don't forget that sodium chloride (Cl- ion) also works as a slow fixer. It was used in the very early days (with salt papers, I think). The soluble silver complex here would be the ion [AgCl2]-. I wonder how well ammonium chloride would work - it is very soluble.
 
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