Architecting Polymeric Beads with Covalent Organic Framework Nanostrands for Fast and Selective Extraction of Neodymium

Covalent organic frameworks (COFs) with regular and tailorable pore channels are promising for constructing advanced adsorbents for the recovery of rare earth ions. However, it remains a challenge to construct composite adsorbents comprising COFs with well-defined morphologies. This study describes a composite bead composed of a polyacrylonitrile matrix and a negatively charged COF, TpPa-SO₃Na, possessing a strand-like morphology for the extraction of Nd³⁺ from aqueous solutions. Porous and crystalline TpPa-SO₃Na nanostrands were synthesized under hydrothermal conditions and exhibited a high adsorption capacity (107.1 mg g^-1), fast kinetics, and good selectivity during Nd³⁺ adsorption. TpPa-SO₃Na nanostrands were further processed into composite beads with a high loading amount of 50%, and the resulting beads effectively maintained the original microstructures and properties of the nanostrands. Importantly, the composite beads can be used in a dynamic process and show excellent recovery efficiency under low or high Nd³⁺ concentrations as well as good operational stability. This work not only demonstrates an evident strategy for preparing composite beads by leveraging a polymer matrix and COF nanostrands but also highlights their great potential in the extraction of sparse precious metal resources, including but not limited to rare earth ions.