Synergy of first-and second-sphere interactions in a covalent organic framework boosts highly selective platinum uptake

Platinum recovery from waste electrical and electronic equipment(WEEE) in highly acidic solutions is significant to the electronics industry and environmental remediation. However, the lack of ingenious design and synergetic coordination gives rise to unsatisfied PtCl_(4)^(2-)extraction capacities and selectivities in most previously reported adsorbents(e.g., polymeric and inorganic materials). Herein, we proposed a synergistic strategy that realizes highly selective PtCl_(4)^(2-)uptake through first-and second-sphere coordinations. The proof-of-concept imine-linked covalent organic framework(SCU-COF-3) was found to chelate Pt Cl42-via the direct N…Pt coordination and the synergistically interlaminar N–H…Cl hydrogen bonds, which was disclosed by the comprehensive analysis of extended X-ray adsorption fine structure(EXAFS) characterizations and density functional theory(DFT) calculations. The unique adsorption mechanism imparts a superior adsorption capacity(168.4 mg g-1)and extraordinary Pt(II) selectivity to SCU-COF-3 under static conditions. In addition, SCU-COF-3 exhibits an upgraded distribution coefficient of 1.62 × 10^(5)mL· g^(-1), one order of magnitude higher than those of reported natural adsorbents. Specifically, SCU-COF-3 can extract PtCl_(4)^(2- )quantitatively from a simulated acidic waste solution coexisting with other 12 competitive ions, suggesting its promising application in practical scenarios.

Superior Iodine Uptake Capacity Enabled by an Open Metal-Sulfide Framework Composed of Three Types of Active Sites

Efficient adsorption of gaseous radioiodine is pivotal for the sustainable development of nuclear energy and the long-termradiation safety of the ecological system.However,state-of-the-art adsorbents(e.g.metal-organic frameworks and covalent-organic frameworks)currently under exploration suffer severely from limited adsorption capacity,especially under a real-world scenariowith extremely lowradioiodine concentration and elevated temperature.This mostly originates from the relatively weak sorption driving forces mainly determinedby the iodine-adsorbent interaction consistingof noncovalent interactionswith a small fraction of strong chemical bonding.Here,we document the discovery of an open metal-sulfide framework((NH_(4))_(2)(Sn_(3)S_(7)),donated as SCU-SnS)constructed by three different types of active sites as a superior iodine adsorbent.Benefiting from the ability of iodine for pre-enrichment into the framework by charge-balancing NH_(4)^(+)through N-H···I interaction,the efficient reduction of I^(2)affording I^(-)by S^(2-),and extremely high binding affinity between Sn_(4)^(+)and I^(-),SCU-SnS exhibit a record-breaking iodine adsorption capacity(2.12 g/g)under dynamic breakthrough conditions and the highest static capacity(6.12 g/g)among all reported inorganic adsorbents,both at 348 K.Its facile synthesis and low cost endow SCU-SnS with powerful application potential for the nuclear industry.

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.