Efficient separation between trivalent americium and lanthanides enabled by a phenanthroline-based polymeric organic framework

Separation of the minor actinides(Am and Cm)from lanthanides in high-level liquid wastes(HLLW)is one of the most challenging chemical separation tasks known owing to their chemical similarities and is highly significant in nuclear fuel reprocessing plants because it could practically lead to sustainable nuclear energy by closing the nuclear fuel cycle.The solid phase extraction is proposed to be a possible strategy but all reported sorbent materials severely suffer from limited stability and/or efficiency caused by the harsh conditions of high acidity coupled with intense irradiation.Herein,a phenanthroline-based polymeric organic framework(PhenTAPB-POF)was designed and tested for the separation of trivalent americium from lanthanides for the first time.Due to its fully conjugated structure,PhenTAPB-POF exhibits previously unachieved stability under the combined extreme conditions of strong acids and high irradiation field.The americium partitioning experiment indicates that PhenTAPB-POF possesses an ultrahigh adsorption selectivity towards Am(Ⅲ)over lanthanides(e.g.,SFAm(Ⅲ)/Eu(Ⅲ)=3326)in highly acidic simulated HLLW and relatively fast adsorption kinetics in both static and dynamic experiments.Am(Ⅲ)can be almost quantitatively eluted from the PhenTAPB-POF packed-column using a concentrated nitric acid elution.The high stability and superior separation performance endow PhenTAPB-POF with the promising alternative for separating minor actinides over lanthanides from highly acidic HLLW streams.

Chromate separation by selective crystallization

A new paradigm to remove toxic chromate anions from aqueous solution by crystallization of chromatewater clusters with imine-linked guanidinium cationic ligands is introduced.The guanidium-based cationic ligand was easily prepared through the imine condensation of an alde hyde and aminoguanidine hydrochloride.The cationic imine-linked guanidinium liga nd(BBIG-CI)showed a high re moval capacity(292.5 mg/g)in the solutions.Rapid decontamination of chromate anions from the wastewater by this cationic ligand was resulted from an instantaneous crystallization.The produced guanidium chromate salts have an extremely low solubility(Ksp,BBIG=8.19×10^9).Such superior removal performance of these mate rials was attributed to the cha rge-assisted hydrogen bonding between the cationic ligand and chromate-water hydrate anions,which was revealed by the single-crystal X-ray diffraction analysis and density functional theory(DFT)calculations.In addition,the succes s ful recove ry of the guanidium-based ligand makes it more attractive for real-world applications.