Ultra‐Selective and Efficient Static/Dynamic Palladium Capture from Highly Acidic Solution with Robust Macrocycle‐Based Polymers

Abstract

The capture of palladium from spent nuclear fuel is crucial for the sustainable development of nuclear energy and resource recovery. One of the most challenging issues in this direction is the survival of adsorbents under extreme reprocessing conditions such as strongly acidic media and high radiation fields while still maintaining high extraction ability and selectivity. Herein, an approach to addressing this issue is reported by incorporating macrocycle into nitrogen‐rich covalent organic polymers (COPs). Dramatically outperforming current adsorbing materials, pillar[5]arene‐based COPs with pyridyl and triazolyl functionalities display record adsorption capacity for Pd(II) at 3 M HNO3 (403 mg g−1), extraordinary stability under 500 kGy gamma irradiation, and ultra‐high selectivity toward Pd(II) over both 17 coexisting cations and six anions. In particular, the material P5COP‐m‐BPT with the best performance also shows remarkable dynamic adsorption efficiency for Pd(II). This study not only provides a strategy to enhance all‐sided adsorption performance in palladium separation with nitrogen‐rich COPs materials but also demonstrates the superiority of customizing advanced materials with macrocycles.

Palladium recovery from acidic solution with phenanthroline-based covalent organic polymers as adsorbents for efficient heterogeneous catalysis

“…6 The raffinate of the PUREX process, named high-level liquid waste (HLLW), is a highly concentrated HNO 3 solution with strong radioactivity containing more than 40 elements, 7 in which palladium (Pd) exists in large quantities. 8 On one hand, Pd has applications in many cutting-edge fields such as pharmaceutics, hydrogen storage devices, and electronics. 9,10 Particularly, Pd is among the most extensively utilized metals for catalysis in many types of reactions including cross-linking, 11 hydrogen evolution, 12 hydrocarbon oxidation, 13 etc ., to name a few.…”

“…In addition, COPs usually show outstanding radiation tolerance due to the presence of relatively large conjugated units which can stabilize to a large degree the radical intermediates. 8 All the advantages of COPs mentioned above are critically required for materials to be employed in HLLW treatment; it is therefore reasoned that appropriately designing novel COP materials can afford highly promising adsorbents for Pd( ii ) recovery from HLLW.…”