US 2019/0287691 Al  1  Sep. 19,2019  SEPARATION OF METAL IONS BY  LIQUID-LIQUID EXTRACTION  CROSS REFERENCE TO RELATED  APPLICATIONS  STATEMENT REGARDING FEDERALLY  SPONSORED R&D  BACKGROUND  Field  Description of the Related Art  SUMMARY  [0012]  In some embodiments, a method for separating  metal ions is provided. The method comprises providing an  aqueous solution comprising a first metal ion and a second  metal ion, wherein the solution has an acidic pH; adding a  HOPO chelator to the aqueous solution; and performing an  extraction against the aqueous solution. The HOPO chelator  functions as a holdback agent to selectively keep the first  metal ion in the aqueous solution, while allowing the second  metal ion to go into an organic phase during the extraction.  [0007]  In some embodiments, a method for enriching a  metal ion is provided. The method comprises contacting a  [0006]  In some embodiments, a method of processing  spent nuclear fuel is provided. This comprises obtaining  spent nuclear fuel dissolved in an acidic medium, contacting  the dissolved spent nuclear fuel with an octadentate ligand  and an organic phase to generate a mixture, and separating  an aqueous phase enriched for Pu 4 +  from the mixture.  [0011]  In some embodiments, a method of separating  trivalent metal ions from tetravalent metal ions is provided.  The method comprises providing an aqueous solution com› prising tetravalent metal ions and trivalent metal ions,  wherein the solution has an acidic pH; adding a HOPO  chelator to the aqueous solution; and performing an extrac› tion against the aqueous solution, wherein the HOPO chela› tor functions as a holdback agent to keep the tetravalent  metal ions in the aqueous solution, while allowing the  trivalent metal ions to be removed via decanting at the end  of the extraction.  [0005]  A few processes, using liquid-liquid extraction, are  under development with limited success in term of selec› tivity and efficacy: TALSPEAK process (USA), GANEX  process (France), and DIAMEX-SANEX process (France).  The purification of the element actinium (Ac $^{3}$+)  is also  catching growing attention. In fact, actinium isotopes are  emerging radioactive sources for cancer treatments such as  the "targeted alpha therapies." The methods of production of  Ac 3 +  isotopes generate Ln 3 +  fission products in addition to  the initial material that is usually made of thorium (Th $^{4}$+).  Current purification protocols for actinium involve numer› ous chromatographic steps that require different chemical  media in order to obtain a purified fraction of Ac $^{3}$+.  [0004]  Owing to concerns related to global warming due  to CO$_{2 }$ emission by traditional energy sources, nuclear  energy has emerged as an alternative energy source. How› ever, disposing of nuclear waste is a major challenge.  [0010]  In some embodiments, a method of separating  metal ions is provided. The method comprises contacting a  liquid composition comprising a plurality of metal ions with  an octadentate ligand to generate a mixture, under condi› tions sufficient to form a metal ion-ligand complex com› prising a metal ion of the plurality of metal ions, and  separating a first fraction of the mixture enriched for the  metal ion-ligand complex from a second fraction depleted  for the metal ion-ligand complex, wherein the first fraction  of the mixture has an acidic pH ofless than 1. The plurality  of metal ions are selected from the group consisting of: a p-,  d- or f-block element of period 5 or greater, a group 3  element, or a group 4 element  [0003]  The present disclosure 1s related to separation  processes for metal ions.  [0009]  In some embodiments, a method of separating  metal ions for nuclear forensics is provided. The method  comprises obtaining a sample derived from a nuclear mate› rial, wherein the sample comprises UO2 2 +, Ac 3 +, Pu 4 +, and  Np $^{4}$+;  contacting the sample with an octadentate ligand to  generate a first mixture, wherein the first mixture has an  acidic pH of 1 or lower; separating UO2 2 +  and Ac 3 +  from  Pu 4 +  and Np 4 +  in the mixture based on an interaction or lack  of interaction between the octadentate ligand and each of  UO$_{2 }$ 2 +,  Ac 3 +,  Pu 4 +,  and Np 4 +,  to generate a second mixture  comprising the Pu $^{4}$+  and Np $^{4}$+;  and further separating each  metal within both mixtures by classical techniques.  [0002]  The invention was made with government support  under Contract No. DE-AC02-05CH 11231 between the  U.S. Department of Energy and the University of California.  The government has certain rights in the invention. This  work was supported by the U.S. Department of Energy,  Office of Science, Office of Basic Energy Sciences, Chemi› cal Sciences, Geosciences, and Biosciences Division at  LBNL under Contract DE-AC02-05CH11231.  [0008]  In some embodiments, a method of preparing a  medical isotope is provided. The method comprises obtain› ing a metallic precursor dissolved under an acidic condition,  wherein the metallic precursor comprises a medical isotope;  contacting the dissolved metallic precursor with an octaden› tate ligand and an organic phase to generate a mixture; and  separating the medical isotope from one or more metal ions  in the dissolved metallic precursor based on an interaction  between the octadentate ligand and the medical isotope.  first aqueous phase with an organic phase to generate a  mixture, wherein the first aqueous phase comprises: a plu› rality of metal ions; and an octadentate ligand, and wherein  the aqueous phase has an acidic pH of less than 1. The  method further includes separating from the mixture a  second aqueous phase enriched for a metal ion of the  plurality of metal ions.  [0001]  This application is a Continuation-in-Part oflnter› national Application No. PCT/US2017/048934, filed Aug.  28, 2017, designating the U.S. and published as WO 2018/  097871 A2 on May 31, 2018, which claims the benefit of  U.S. Provisional Application No. 62/505,458, filed on May  12, 2017 and 62/401,687, filed on Sep. 29, 2016, which is  hereby incorporated by reference in its entirety. Any and all  applications for which a foreign or a domestic priority is  claimed is/are identified in the Application Data Sheet filed  herewith and is/are hereby incorporated by reference in their  entireties under 37 C.F.R. § 1.57. 