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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 PtCl42− 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 PtCl42− uptake through first- and second-sphere coordinations. The proof-of-concept imine-linked covalent organic framework (SCU-COF-3) was found to chelate PtCl42−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 × 105 mL g−1, one order of magnitude higher than those of reported natural adsorbents. Specifically, SCU-COF-3 can extract PtCl42− quantitatively from a simulated acidic waste solution coexisting with other 12 competitive ions, suggesting its promising application in practical scenarios. [ABSTRACT FROM AUTHOR]

99Tc is a long-lived radionuclide present in large amounts as TcO4- anion in used nuclear fuel. Its removal from the waste stream is highly desirable because of its interference capability with actinide separation and its volatile nature during the nuclear waste vitrification process. Despite the progress achieved in the past few years, the design of anion-exchange materials with optimized Tc uptake property and improved stability under the extreme condition, is still a research goal beneficial for reducing the volume of secondary radioactive solid waste generated during the waste partitioning process. However, their design philosophy remains elusive, with challenges coming from charge repulsion, steric hindrance, and insufficient reactive sites within the materials. Herein, we present a design philosophy of cationic polymer network materials for TcO4- separation by systematic precursor screening and structure prediction. This affords an optimized material, SCU-CPN-2 (SCU=Soochow University), with extremely high positive charge density while maintaining high radiation resistance. SCU-CPN-2 exhibits a record high adsorption capacity (1,467 mg/g towards the surrogate ReO4-) compared to all anion-exchange materials reported up to date. In addition to ultrafast adsorption kinetics, SCU-CPN-2 has remarkable selectivity over nitrate and sulfate, and facile recyclability. [ABSTRACT FROM AUTHOR]

Crystalline solids of zeolitic imidazolate framework (ZIF)-69 with a suitable pore window size matching with atomic diameter of xenon is utilized for this task, showing notable performance for Xe/Kr capture and separation as well as decent hydrolytic and irradiation stabilities. The results illustrate that the saturated uptake amount of Xe by ZIF-69 is 2.46 mmol/g at 298 K, while Kr uptake is only 0.55 mmol/g. Importantly, the separation ratio of Xe/Kr is 8.35, one of the highest values among all solid sorbent material reported up to now. These findings suggest that ZIF-69 is a potential candidate for the application of xenon capture and purification form a gas mixture containing Kr. [ABSTRACT FROM AUTHOR]