[johnk]

Hello,

Can someone please help me produce boric acid flakes such as in the image below. I am also putting up a CHNO and PIXE test so maybe it can help identify some elements that may have been used.

[Arkcon]

I really don't know what you're asking.  I'm guessing you want to crystallize flakes of boric acid in a particular way, but I figure those pictured are due to the way they were crystallized, maybe from a solution, not to fast yet not too slow.  I don't know how you figure the trace element profile is very important for the crystalline habit.

[johnk]

Sorry to be exactly clear. Yes I want to recrystallize boric acid. The flakes as seen in photo came into my possession from a client who requires boric acid flakes just like those.

So I am trying to figure out how can I recrystallize boric acid to appear very similar to those flakes?

I have tried just water and they come out granular and greasy.

The sample I have is slippery, will not turn into powder, remains flakes to the smallest bit. And are soft feeling. They are layered. I would say they even resemble mica flakes.

Does anyone know how I can get this result by recrystallizing boric acid?

[johnk]

Also in addition, the trace element profile, I was hoping someone that is very familiar with boric acid could take a look at it and maybe identify any elements that may have been added, for example, sulfuric acid, hcl acid? Or anything else that may cause the result of the crystals.

If someone does have the answer to my problem but charges a fee for help do not hesitate to let me know.

[AWK]

Jusdt add diluted HCl slowly to solution of borax.

[johnk]

thanks I tried this, don't know if I could have done something wrong but it didn't work, it just made simple powder what seems to look like boric acid... any other suggestions? thanks

[cth]

You could try to evaporate off solvent using rotary evaporator. It often gives dry solid with flake shape when you scrub the flask.

[johnk]

Thanks I've actually tried something similar like this already but no luck. I really need them to look as lustrous as the photo above and also have the flakes form. I don't know how nobody seems to know how to achieve this? I've been at it for a while. Thanks!

[discodermolide]

I'm not sure if boric acid has multiple polymorphic forms,you can check this. But if it does see if the flakes correspond to a different form than the granules (which may be amorphous). If that is the case get yourself some flakes and add them as a seed to the re-crystallisation solution and let it crystallise slowly. If you are lucky you may well get flakes out!

[johnk]

I'm not sure if boric acid has multiple polymorphic forms,you can check this.

Good advice but no luck. Comes back granular. I guess it is polymorphic. Just cannot get a clue as to what temperatures or solutions and timings. Any chance I can personally send you a sample? As I said before. Willing to pay for some help on this.

[MOTOBALL]

Suggest you check the following sources.

1.  "The Kirk-Othmer Encyclopedia of Science & Technology" multi-volume set; should be available in large univ. library.  Almost certainly will have section on B(OH)3.

2.  Patent Office for xtlln/prepn. of B(OH)3 as flakes (are they pearlescent ?)

Please let us know if this helps.

Regards,

Motoball

[Siberia]

I am trying to crystallize boric acid to obtain flakes as seen in this picture:

https://sc01.alicdn.com/kf/HTB1m0slIFXXXXbRXFXXq6xXFXXXD/boric-acid-flakes-1-3mm-and-3.jpg


I have tried recrystallizing out of water and out of methanol but the crystals I get more resemble sodium chloride crystals than the crystals in the picture. Any idea of how I can obtain the flake like crystals in the picture?

[AWK]

Try very, very slow crystallization in closed vessel (eg twist-off jar in pot with hot water)

[Arkcon]

Siberia:, I hope you don't mind that I've merged your question with a much older one.  What you want to achieve is more difficult than you might expect.

[Siberia]

Hi Arkcon,

No problem - I had actually seen this thread earlier but didn't find a satisfactory answer in it. I will try the very very slow crystallization as suggested by AWK, but are there any other tips you can give me?


Maybe it'll help if I am more specific about what I did: So I crystallized out of water. I brought 100 mL of water to a boil and made a saturated solution of the boric acid. I poured that boiling water into another beaker and let it cool to room temperature, which took about a half hour or so. I then put it in the fridge for 10 minutes, followed by an ice bath for 15 minutes. I filtered out the crystals. The crystals that were floating on top of the solution were flat and flake-like. They were also pearlescent, just like the ones in the picture above - though they were quite small . The crystals that settled on the bottom and that were stuck to the side were more granular, like salt.

So what I did partially worked. Based on what I just described, any more advice?