Design Strategies to Enhance Amidoxime Chelators for Uranium Recovery

Bio-inspired antibacterial cellulose paper-poly(amidoxime) composite hydrogel for highly efficient uranium(vi) capture from seawater

A bio-inspired cellulose paper-poly(amidoxime) composite hydrogel is explored via UV-polymerization. This hydrogel has a highly efficient uranium capture capacity of up to 6.21 mg g^-1 for W_U/W_dry gel and 12.9 mg g^-1 for W_U/W_{poly(amidoxime)} in seawater for 6 weeks, due to its enhanced hydrophilicity, good hydraulic/ionic conductivity and broad-spectrum antibacterial performance.

Porous Aromatic Frameworks (PAFs)

Porous aromatic frameworks (PAFs) represent an important category of porous solids. PAFs possess rigid frameworks and exceptionally high surface areas, and, uniquely, they are constructed from carbon-carbon-bond-linked aromatic-based building units. Various functionalities can either originate from the intrinsic chemistry of their building units or are achieved by postmodification of the aromatic motifs using established reactions. Specially, the strong carbon-carbon bonding renders PAFs stable under harsh chemical treatments. Therefore, PAFs exhibit specificity in their chemistry and functionalities compared with conventional porous materials such as zeolites and metal organic frameworks. The unique features of PAFs render them being tolerant of severe environments and readily functionalized by harsh chemical treatments. The research field of PAFs has experienced rapid expansion over the past decade, and it is necessary to provide a comprehensive guide to the essential development of the field at this stage. Regarding research into PAFs, the synthesis, functionalization, and applications are the three most important topics. In this thematic review, the three topics are comprehensively explained and aptly exemplified to shed light on developments in the field. Current questions and a perspective outlook will be summarized.

Regenerable and stable sp2 carbon-conjugated covalent organic frameworks for selective detection and extraction of uranium

Uranium is a key element in the nuclear industry, but its unintended leakage has caused health and environmental concerns. Here we report a sp2 carbon-conjugated fluorescent covalent organic framework (COF) named TFPT-BTAN-AO with excellent chemical, thermal and radiation stability is synthesized by integrating triazine-based building blocks with amidoxime-substituted linkers. TFPT-BTAN-AO shows an exceptional UO22+ adsorption capacity of 427 mg g-1 attributable to the abundant selective uranium-binding groups on the highly accessible pore walls of open 1D channels. In addition, it has an ultra-fast response time (2 s) and an ultra-low detection limit of 6.7 nM UO22+ suitable for on-site and real-time monitoring of UO22+, allowing not only extraction but also monitoring the quality of the extracted water. This study demonstrates great potential of fluorescent COFs for radionuclide detection and extraction. By rational designing target ligands, this strategy can be extended to the detection and extraction of other contaminants.

Skeleton Engineering of Homocoupled Conjugated Microporous Polymers for Highly Efficient Uranium Capture via Synergistic Coordination

Developing efficient adsorbents for uranium enrichment is of great significance for resource sustainability and environmental safety. This study presents a facile and adaptable post-synthetic strategy to prepare highly efficient uranium adsorbents via engineering the π-conjugated skeletons of homocoupled conjugated microporous polymers (HCMPs). Taking advantage of the diyne units in the π-conjugated skeletons, bis-amidoxime uranophiles, one of the state-of-the-art ligands of uranyl ions, were introduced to the frameworks of HCMPs. The functionalized HCMPs preserved the interconnected 3D microporous networks and rigid conjugated skeletons with abundant bis-amidoxime ligands uniformly distributed in the pore channels. Such structural advantages of the adsorbents afforded very fast adsorption kinetics within 15 min to reach the equilibrium and high capacity of uranium (450 mg/g). Moreover, DFT calculation suggests a synergistic coordination as the most energetically favored coordination mode of the uranyl/bis-amidoxime complexes. This study contributes new insights into the underlying mechanism responsible for the highly efficient adsorption ability of the bis-amidoxime-functionalized HCMPs toward uranium. Meanwhile, the synthetic methodology established here could be extended to task-specific design and skeleton engineering of more functional HCMPs for broadened applications.

Exploration of advanced porous organic polymers as a platform for biomimetic catalysis and molecular recognition

This Feature article summarizes our progress in the design of biomimetic POPs for catalysis and molecular recognition with enhanced performance.

Hollow cobalt sulfide for highly efficient uranium adsorption from aqueous solutions

The preparation of hollow Co₃S₄nanostructures by ZIF-67 guarantees high uranium adsorption performance in aqueous solutions.