dissolving edta

[milky]

The image and the webpage title that shows up in the browser tab both say 'tetrasodium' but the heading on the page itself says 'disodium', so there's some screw up here, somehow.

They changed the title and replied to my email asking about it. Here's what they said:
"We appreciate your business and interest in our products! It looks like you are correct, we have an error on this product type / name, its Disodium EDTA not Tetrasodium EDTA. I apologize for this error and if you would like to return we will send you out a prepaid return label for a full refund. "

So.. now we know. Big mistake on their part but good customer service so far. I'll see how returning goes.

 

[milky]

The di and tetra EDTA are nothing more than the acid form that was already treated with NaOH for convenience.

Can di EDTA be turned into tetra? It's probably not something I'll want to bother with but if it saves me from having to buy more elsewhere then maybe..

Edit: Ah, I see what you meant now. Upon looking it up, it appears that tetra and di EDTA are interchangeable so long as you account for the pH and buffer as needed. Is there a way to get the pH right without strips or an acid meter? What about making a balanced equation and weighing it out?

 

[Soapmaker145]

Can di EDTA be turned into tetra? It's probably not something I'll want to bother with but if it saves me from having to buy more elsewhere then maybe..

Edit: Ah, I see what you meant now. Upon looking it up, it appears that tetra and di EDTA are interchangeable so long as you account for the pH and buffer as needed. Is there a way to get the pH right without strips or an acid meter? What about making a balanced equation and weighing it out?

You got it. If you add enough NaOH to the di EDTA, you end up with the tetra. You can even add KOH. It isn't any different than neutralizing citric acid or vinegar with NaOH before adding it to the rest of the soaping lye.

You can get the pH right if you add NaOH slowly and allow the EDTA to dissolve. Add 0.5 g of NaOH to your solution and stir to dissolve for few minutes. If it doesn't clear, add 0.5g to 1g at a time until it's all dissolved. If what you have is EDTA, it'll go in solution without any problems. pH paper is very convenient to check the pH. It takes the guesswork out.

The disodium salt shouldn't need much NaOH to dissolve. I'll check what forms of EDTA I have in stock tomorrow. I'll be able to tell you exactly how much NaOH you need to add if I have the right form.

 

[cmzaha]

Hate to say this, but maybe the supplier is selling this as discontinued item with no return and no refund for a reason other than "it's not selling well"?

It actually does state that clearance items Can be returned in 10 days

 

[DeeAnna]

I stand corrected. Thanks, Carolyn!

 

[Soapmaker145]

If you decide to do this, do it on a small scale in a well ventilated space and wear protection particularly for the face just in case what you have is not EDTA.

I don't have disodium EDTA but I have the acid form. I measured 23 g of the acid EDTA (fine powder) and added 50g of water and got the same slurry that is in the pictures. I added 10 g of NaOH while stirring. It heated up instantly and everything was dissolved in under a minute. The solution cleared completely. The pH at that point was between 7 and 8. I added another 1.5g of NaOH to take the pH to about 9. If it takes ~50% as much NaOH as EDTA to dissolve the EDTA form you have, it's the acid form. If you get a clear solution with significantly less NaOH, you have the disodium salt. The EDTA acid I'm using is >99% pure. The purity of the chemical you have may vary but should be above 95%.

I shouldn't have added the NaOH all at once because the solution overheated and wanted to boil. If you try it, add the NaOH in 3 to 4 installment to avoid overheating. This way, if you have the disodium form, you'll be able to figure it out because the chemical will not need as much NaOH to dissolve.

The last thing to consider is to reduce the amount of the acid EDTA used in the soap since gram for gram, there is more EDTA in the acid form than there is in the tetra form.

If you don't trust the supplier, you can always trash it or return it.