I would like to ask if anyone knows how to remove Calcium and Iron from solutes and maintaining/isolating other elements such as Ra, Am, Po, Pu, Th and U.
From the litterateur I have read, I seem to understand the following;
1) Ascorbic acid reduces Fe(III) to Fe(II)
2) Oxalic acid will precipitate with Fe(II) (at which pH and medium?)
3) In pH 4, Calcium is maintained in solution while Ra precipitates when adding Sodium chromate (in what medium?)
4) In organic solvents like TBP, Fe and Ca is not extracted, while hexa- and tetravalent elements are.
5) FeOH precipitate at pH 8 and can co-precipitate many other elements
The problem is how to combine the steps, in which order and should other steps be included?
I was thinking to start off in HNO3, 8M, pouring the solute in TBP to extract hexa- and tetravalent elements - U and Th which create complexes with nitrates, hopefully also the Pu(IV) anyone knows for sure?
In aqueous phase one should find Ca, Fe, Ra, Po and Am.
Back-extraction of Th can be done with 2M HCl, and U with distilled water (in that order) due to breaking of complexation bond with the organic solvent, so that is great.
However, what to do and how to proceed with the aqueous phase, which is in 8M HNO3?
Possible next steps?;
A) Dilute with distilled water, add a lot of ammonia and precipitate the FeOH, what will co-precipitate with it? What will remain?
B) Chromate precipitate? How to do in 8M HNO3?
C) Ba-Sulfate precipitate to precipitate Ra? How to do in 8M HNO3?
Thank you very much for your time reading so far
And I appreciate any comments and suggestions