Boric Acid Help Please!

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Does anyone here know how to crystallize boric acid? I've been reading all sorts of stuff online and don't know what is right.

 

Borax under HCL acid?

Boric acid under sulfuric acid?

 

Does anyone have the correct method?

 

Thanks

[John Cuthber]

Why do you want to crystallise it?

Why not just use water?

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Have a client who wants to buy it crystallized, I tried with water, didn't really seem to work, reverts back to powder, there's a method to make it into crystals/flakes.

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Please check out this link. And take a look at the photo. This is basically what I want to learn. How can I transform boric acid into this?

 

Thanks!

 

http://www.ebay.co.uk/itm/Boric-Acid-Flakes-1kg-insecticide-antiseptic-/190577869343

[John Cuthber]

I have produced crystals of boric acid like those in the picture. I did it when I was a school kid "playing " with chemistry so it certainly isn't difficult.

 

Exactly what did you do that didn't work?

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Way to be a show off but I cannot seem to get them!!

 

I tried 1. Boiling boric in water, waiting for it to cool, upon cooling filtering it out of water, once they had dried, it seemed to be just boric again...

 

2. I have tried same thing but with adding diluted H2S04 (half weight of boric) so example 2g boric 0.5 H2S04 with 0.5 water dilute. This gave me a paste...

 

I have been trying to figure this out but no help! I hope you can help!

 

Thanks!

 

I have produced crystals of boric acid like those in the picture. I did it when I was a school kid "playing " with chemistry so it certainly isn't difficult.

 

Exactly what did you do that didn't work?

[John Cuthber]

Weigh out some boric acid (say 100 grams).

Put it in a suitable container. A glass saucepan would be good. Add 4 times as much water (so, for 100 grams you need about 400 ml of water).

Heat the mixture until it boils gently and stir it.

Once the liquid is boiling all the boric acid should dissolve. (Borates have a reputation for dissolving rather slowly so it may take some time. Keep an eye on the water level. If lots of it evaporates as you boil it you might need to add some more hot water.).

Once all, or almost all of the solid has dissolved stop stirring and stop heating the solution. Let any solid material settle out.

Pour the liquid into another container leaving any undissolved material behind.

Let the hot solution cool slowly.

It should form crystals like those in the picture you linked to.

Pour off the liquid from the crystals ( it probably makes sense to put it back in the saucepan.)

Wash the crystals with a little cold water and filter them out of the solution. A fairly fine sieve is probably better than filter paper for this because you won't get bits of paper in the crystals.

 

You should get most (about 60% or 70%) of the boric acid back as crystals.

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Hey,

 

So I tried the experiment, I got basically what I had gotten before, unfortunately it doesn't look entirely like the photo. I got vitreous crystals which is a good thing because it's a property the flakes have the same shine. However, the flakes that I have in my hand, they stick together well in form of layers and it actually flakes, they are softer and slippery feeling. The one I got from water still sort of feels like boric acid/greasy and does not stick together.

 

My friend had analyzed a sample of the flakes for me, he did identify it as boric acid but, he is not any good with borons so he couldn't help me more, but what he did say was that the solution was more acidic than he would expect boric acid alone to be.

 

I'm starting to think that maybe they crystallize just the way you told me to do but add an acidic solution so they come out feeling and looking different?

 

The level of pH of water solution at room temp ~4-5. is what my friend got.

 

Would you happen to have any more ideas on what I could try? I really appreciate it.

 

Thanks!

[John Cuthber]

Boric acid is a very poor acid so the pH looks OK to me.

It should crystallise out as flakes from hot water. The other way that often gets good crystals is to let a solution of it evaporate slowly.

 

Incidentally, I just noticed in the first post you talk about boric acid and borax.

They are not the same thing. Which one do you mean?

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Sorry the Borax was a mention, I read online that if you crystallize Borax under HCL Acid, then it turns into boric acid flakes, so I wasn't sure which one would result to be what I am looking for.

 

I also have CHNO and PIXE tests maybe someone can take a look and see if something extra is added?

 

Carbon: 0.22%

Hydrogen: 4.45%

Nitrogen: <0.05%

Oxygen: 23.36%

 

PIXE TEST:Check attachment.

 

Also can you look at better photo and confirm you've made flakes like this once again?

 

On the same note for curiosity, does Borax crystallize like this? I have tried Borax and it gives salt like crystals which I read people use to make decorative snow flakes. My friend is 99% on the flakes being Boric, but if some how Borax can give the same appearance I can try it and see if it's closer to the sample I have.

 

Can someone also clear this up for me??

 

This is what I keep finding online and it confuses me. When I google description of my sample. I get mainly:

 

Boric acid from Borax :- Concentrated HCL or H2SO4 is added to a hot

and saturated solution of borax, boric acid is produced. The product is cooled, when

pearly white silky crystals of boric acid separate out. These are washed and purified by

recrystallization from hot water.

[John Cuthber]

I think your friend is probably right. A green flame test, and no sodium (or anything else much) in the PIXE elemental analysis , the crystals shape etc are fairly good evidence to support boric acid as a conclusion.

 

If it was borax it would have a lot more sodium in it.

I'd be a fool to claim I can do analysis by looking at a picture on the web, but I think it is very likely that the material you have is boric acid.

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Yes, and by getting a good look at the photo, would you still say your flakes looked like this? Or do you believe something is being added to change texture/appearance?

 

Why do they add concentrated HCL or H2SO4 do you know?

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In addition, I did the slow boil, didn't really help much, I get what you mean that it produces bigger chunks, however, it's still a completely different texture, but as I said before it does have flakes of very shinny small flakes which is a good thing I guess.

 

Any help appreciate.

[Suxamethonium]

So, when you did the recrystalisation before, letting the solution cool- you said you got the right sort of crystals, but they didn't compact to form the flake?

 

What I feel is likely to have happened was that you got a bigger crystal (same shape and texture, but the increased size wouldn't compact as easy). You could try to induce smaller crystals by precipitating them from solution faster (i.e. rapid cooling (on ice) and scratching the bottom with a glass rod to induce precipitation). As spectulation, I would imagine industry would cool and induce precipitation in such a way because it is easy to do, and quickens the overall process- this might be why they achieve the smaller, more compactable crystals.

[John Cuthber]

The reason for adding the acid (Hydrochloric or sulphuric) is to turn the borax into boric acid.

As you already have boric acid you don't need to do that.

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Yes exactly, I am not sure if it's the fact that the crystals are too big, when I compare it to my sample/photo it's not the same texture at all. Like mentioned before they don't compact together, they aren't slippery feeling, or even smooth and they break into powder very easily.

 

My sample is pretty much the opposite, soft silky, smooth, slippery, and it will break into small flaky layers. Like mica basically. Even looks like mica.

 

About the HCl acid, I should have been clear, I mean could it be possible that when borax is transformed into boric that it forms to be like this?

 

 

So, when you did the recrystalisation before, letting the solution cool- you said you got the right sort of crystals, but they didn't compact to form the flake?

 

What I feel is likely to have happened was that you got a bigger crystal (same shape and texture, but the increased size wouldn't compact as easy). You could try to induce smaller crystals by precipitating them from solution faster (i.e. rapid cooling (on ice) and scratching the bottom with a glass rod to induce precipitation). As spectulation, I would imagine industry would cool and induce precipitation in such a way because it is easy to do, and quickens the overall process- this might be why they achieve the smaller, more compactable crystals.

[John Cuthber]

The boric acid can't remember what it was before.

[Suxamethonium]

No it can't remember what it was before, but thats not to say something won't crystalise differently at a different pH. This is probably much more prudent in organic structures, but whilst unlikely to change anything you could always try and see if your recrystalisation is any different in acidic conditions- it wont really matter what acid you use (provided it's a simple acid and not something thats going to completely complex with your boric acid) HCl or H₂SO₄ should be fine- may as well try different concentrations whilst you're at it.

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Hey, it's been a while and unfortunately still haven't solved my issue. I need crystals like in the photo above. I don't know if some how I could have done something wrong to your method? Can you "John C" tell me that your crystals were identical to mine? I tried your method a couple of times all I get is just boric acid as it is. What can I be doing wrong?

 

I have also tried with HCL acid and Sulfuric acid, I don't know again if I am doing something wrong, but no luck getting this! I have talked to other people on the subject, everyone who looks at the photo is not sure either but imagine it could be from sulfuric or nitride?

 

Any help guys?

 

 

Weigh out some boric acid (say 100 grams).

Put it in a suitable container. A glass saucepan would be good. Add 4 times as much water (so, for 100 grams you need about 400 ml of water).

Heat the mixture until it boils gently and stir it.

Once the liquid is boiling all the boric acid should dissolve. (Borates have a reputation for dissolving rather slowly so it may take some time. Keep an eye on the water level. If lots of it evaporates as you boil it you might need to add some more hot water.).

Once all, or almost all of the solid has dissolved stop stirring and stop heating the solution. Let any solid material settle out.

Pour the liquid into another container leaving any undissolved material behind.

Let the hot solution cool slowly.

It should form crystals like those in the picture you linked to.

Pour off the liquid from the crystals ( it probably makes sense to put it back in the saucepan.)

Wash the crystals with a little cold water and filter them out of the solution. A fairly fine sieve is probably better than filter paper for this because you won't get bits of paper in the crystals.

 

You should get most (about 60% or 70%) of the boric acid back as crystals.

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Haven't been on in a white, however, still searching for my answer, any help?

 

Thanks

[John Cuthber]

It was a long time ago that I did this but, as far as I can recall the crystals of boric acid I got were flat and shiny like the ones in your picture. That is the characteristic shape of boric acid crystals (in much the same way that salt crystallises as little cubes).

What are you hoping to get?

If you want a powder you can always grind the crystals.

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I am hoping for large and very flaky crystals as in the picture. These crystals are not clear/see through, is that what you had? These are actually a mother of pearl color, soft, silky and very flaky, they slip/flake off each other.

[John Cuthber]

You can usually get bigger better made crystals by cooling a solution slowly so the crystals form slowly.

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It's just not working. Something else finally came to mind. Could it be that there is a different grade of boric makes different crystals? And if that is possible. Is there a way for me to test my sample and identify it's grade?

 

Thanks

 

You can usually get bigger better made crystals by cooling a solution slowly so the crystals form slowly.

[Redwhitechem]

The result of different borax concentrations on the growth and termination rates of boric acid crystals were measured in a fluidized bed crystallizer under fixed conditions of super saturation and under saturation and fluidization.