Cotton fiber functionalized with 2D covalent organic frameworks for iodine capture

By using a rapid cryogenic reaction, cotton fiber was covalently functionalized with imine-linked two-dimensional covalent organic frameworks (2D COFs), which was synthesized via an imine condensation reaction between 1,3,5-tris(4-aminophenyl)benzene and terephthaldehyde. The resulting functionalized cotton (COFs@cotton) was characterized by fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscope, thermo-gravimetric analysis, nitrogen adsorption–desorption analysis and elemental analysis. The presence of a lot of imine functional groups in combination with dispersed mesoporous holes results in rapid adsorption rate and relatively high iodine affinity with uptake capacities up to 533.9 mg/g, which was much higher than that of untreated cotton. In addition, COFs@cotton also shows remarkable capability as absorbent for iodine in solution. The adsorbed iodine can be completely extracted from COFs@cotton by being washed with ethanol, permitting the simple reuse of adsorbent. This new functionalization approach can be applied to different kind of imine-linked COFs, and the corresponding adsorbents show more extensive practical application prospect for iodine capture. Graphic abstract