Melamine-induced novel MSONs heterostructured framework: Controlled-switching between MOF and SOF via a self-assembling approach for rapid uranium sequestration

摘要

SOFs and functionalized-MOFs provide potential opportunities for sequestering uranium from radioactive solution. Nevertheless, the nonporous architecture caused by supramolecular reunion as well as the collapse of MOFs structure by chemical modification step remain an inevitable challenge for further uranium recover and treatment. Herein, we proposed a novel melamine-induced strategy for the first preparation of heterostructured framework (MSONs) based on a self-assembling approach to realize a controlled-switching of structure between MOF and SOF. The MSONs adsorbent was directly constructed using N-donor-containing MA and O-donor-containing TMA as the building units. And then the high-nuclearity metal ions were inserted into the topological structure of SOF to snatch abundant building active sites when they competed with MA to interact with three O-containing linkers on both sides of each TMA molecule. The subsequent chemical modification and supramolecular reunion phenomenon can be effectively avoid by transforming the topology architectures from original MOF-dominated polyhedron to SOF-dominated elongated nanotubes. The obtained MSONs was characterized by SEM, XPS, XRD, TGA and FT-IR spectrometry. Among six kinds of MSONs adsorbents, MSONs-5 exhibited an extremely high UO22+ loading capacity (526.6 mg/g) during the morphological transformation process, which exceeds the most of the previously reported powerful uranium adsorbents. Taking advantage of this extraordinary heterostructured framework and multiple interactions, MA-induced MSONs can be treated as a promising candidate for uranium sequestration.