SE-72/AS-72 generator system based on Se extraction/ As reextraction
View Patent ↗The preparation of a 72 Se/ 72 As radioisotope generator involves forming an acidic aqueous solution of an irradiated alkali bromide target such as a NaBr target, oxidizing soluble bromide in the solution to elemental bromine, removing the elemental bromine, evaporating the resulting solution to a residue, removing hydrogen chloride from the residue, forming an acidic aqueous solution of the residue, adding a chelator that selectively forms a chelation complex with selenium, and extracting the chelation complex from the acidic aqueous solution into an organic phase. As the 72 Se generates 72 As in the organic phase, the 72 As may be extracted repeatedly from the organic phase with an aqueous acid solution.
1. A method for preparing a 72 Se/ 72 As generator, comprising
forming an aqueous acidic solution of an irradiated target of an alkali bromide, the aqueous acidic solution comprising hydrogen chloride and soluble bromide and water solvent, the irradiated target comprising radioisotopes of selenium that include 72 Se,
oxidizing the soluble bromide to elemental bromine,
removing the elemental bromine from the solution,
evaporating the water solvent to provide a residue,
forming an acidic aqueous solution of the residue, the acidic aqueous solution comprising a chelator suitable for forming a soluble chelation complex with 72 Se,
extracting the soluble chelation complex with 72 Se from the acidic aqueous solution into a liquid organic phase not miscible with the acidic aqueous solution, thereby preparing 72 Se/ 72 As generator.
2. The method of claim 1 , further comprising the step of irradiating an alkali bromide target with protons under conditions suitable for the production of 72 Se.
3. The method of claim 1 , wherein the alkali bromide target comprises sodium bromide.
4. The method of claim 1 , wherein the organic phase that is not miscible with the acidic aqueous solution comprises a liquid organic phase.
5. The method of claim 4 , wherein the liquid organic phase comprises a compound selected from 1,4-dioxane, diethyl ether, tert-butyl methyl ether, a hexane, a cyclohexane, an ester, tetrahydrofuran, and an alcohol.
6. The method of claim 5 , wherein the ester is selected from ethyl acetate, ethyl formate, methyl propionate, ethyl propionate, butyl propionate, methyl formate, methyl benzoate, and wherein the alcohol is selected from a butanol and a pentanol.
7. The method of claim 5 , wherein the liquid organic phase comprises ethyl acetate.
8. The method of clam 1 , acidic aqueous solution of the residue comprises a pH from about pH 0.5 to about pH 2.0.
9. The method of claim 1 , wherein the chelator is selected from R—COOH, R—COO—, a di-carboxylic acid, a conjugate base of a di-carboxylic acid,
wherein R comprises an aliphatic group, an aromatic group, or combinations thereof.
10. The method of claim 9 , wherein R is selected independently from methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, aryl, and substituted aryl.
11. The method of claim 9 , wherein the chelator is a dithiocarbamate.
12. The method of claim 9 , wherein the chelator is selected from oxalic acid and oxalate.
13. A method for producing 72 As, comprising:
forming an aqueous acidic solution of an irradiated target of an alkali bromide, the aqueous acidic solution comprising hydrogen chloride and soluble bromide and water solvent, the irradiated target comprising radioisotopes of selenium that include 72 Se,
oxidizing the soluble bromide to elemental bromine,
removing the elemental bromine from the solution,
evaporating the water solvent to provide a residue,
forming an acidic aqueous solution of the residue, the acidic aqueous solution comprising a chelator suitable for forming a soluble chelation complex with 72 Se,
extracting the soluble chelation complex with 72 Se from the acidic aqueous solution into liquid organic phase not miscible with the acidic aqueous solution, the liquid organic phase comprising a 72 Se/ 72 As generator, and
extracting 72 As from the 72 Se/ 72 As generator into an aqueous phase that includes a soluble chelator and contacting this aqueous solution with an anion exchanger to remove selenium from this aqueous phase.
14. A 72 Se/ 72 As generator, comprising a soluble complex of 72 Se bonded to a chelator in an organic phase, the chelator selected from R—COOH, R—COO − , a dicarboxylic acid, a conjugate base of a dicarboxylic acid,
wherein R comprises an aliphatic group, an aromatic group, or combinations thereof.
15. The generator of claim 14 , wherein R is an aliphatic group or selected independently from methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, aryl, and substituted aryl.
16. The generator of claim 14 , wherein the organic phase is selected from 1,4-dioxane, diethyl ether, tert-butyl methyl ether, a hexane, a cyclohexane, an ester, tetrahydrofuran, and an alcohol not miscible with water.
17. The generator of claim 16 , wherein the ester is selected from ethyl acetate, ethyl formate, methyl propionate, ethyl propionate, butyl propionate, methyl formate, and methyl benzoate.
18. The generator of claim 17 , wherein the ester is ethyl acetate.
19. The generator of claim 14 , wherein the dicarboxylic acid is oxalic acid and the conjugate base of the dicarboxylic acid is oxalate.