Ultrafast solid-phase synthesis of 2D pyrene-alkadiyne frameworks towards efficient capture of radioactive iodine

Abstract

Iodine (I2) capture over adsorbents has great potential for the treatment of radioactive nuclear wastes. Herein, we develop a direct synthesis of 2D structured pyrene-alkadiyne frameworks, poly(1,3,6,8-tetraethynylpyrene) (PTEP), through a facile and ultrarapid solid-phase thermal polymerization of 1,3,6,8-tetraethynylpyrene (TEP) monomers in air. With this way, only single chemical of TEP is used without any catalysts, templates, solvents, and waste emissions. The PTEP frameworks feature high content of periodically distributed pyrene groups, regular intra-plane big rings, and 2D interlamellar structure, which endow PTEP with abundant electron-donors, high and accessible specific surface area as well as low resistance of mass transfer. PTEP exhibits high I2 capture capacity (3380 mg g−1 for vaporous I2 at 75 °C and 2570 mg g−1 for aqueous solution at 25 °C), fast adsorption kinetics (1350 mg g-1h−1 at 75 °C), strong water tolerance, thermal stability, and reliable reusability for the adsorption of vaporous I2 and I2 aqueous solution, which are superior to most of current sorbents. The experiments and modellings suggest that I2 adsorption on PTEP refers to the Langmuir adsorption model and the pseudo-second-order adsorption kinetics, in which the adsorbed iodine exists as polyiodide I5-via accepting electrons mainly from pyrenes.