Electron-rich COFs with a bis-triphenylamine structure as the main chain: Ultrafast and ultrahigh iodine capture

Abstract

The construction of ideal adsorbents for the capture of radioiodine usually requires high adsorption capacity and high adsorption rate. However, this is still a challenging problem. The advantages of COFs based on their good crystallinity, pore order, and structural diversity make COFs ideal adsorbents. Here, we developed three novel electron-rich COFs based on the triphenylamine, which have good chemical, thermal, and radiation-resistant stability and are suitable for the harsh environment of radioactive iodine therapy. Upon the introduction of heteroatom N/S, TAPD-PDB and TAPD-TDB exhibited amazing adsorption capacities (75 °C: 7.88 g g and 6.98 g g, 25 °C: 4.46 g g and 3.62 g g), while the adsorption rates, K, are significantly increased to 5.34 g gh and 4.22 g gh, which is higher than most of the reported iodine adsorbents. It was surprising that COFs also have excellent adsorption properties for iodine in cyclohexane solution up to 1260 mg L. FT-IR, XPS, Raman and electrostatic potential calculations indicate that the ultrafast and ultrahigh iodine uptake of COFs can be attributed to the interplay of their rich electronic structure, efficient adsorption sites, helical conformation and charge transfer. This study shows the efficient and ultrafast removal of iodine from nuclear wastewater and nuclear exhaust gas by electron-rich COFs.