Effective Iodine Adsorption by Nitrogen-Rich Nanoporous Covalent Organic Frameworks

With the rapid development of the nuclear industry, the effective treatment of radioactive iodine has currently become an urgent but challenging task. Herein, two covalent organic frameworks (COFs), TFBT-1 and TFBT-2, were successfully synthesized for iodine adsorption. Structure analysis revealed that they are both nanoporous materials with one-dimensional channels derived from the packing of the related two-dimensional frameworks. Iodine adsorption experiments demonstrated that both COF materials exhibit effective performance for iodine adsorption, with a maximum amount of upto 3.15 g g–1 for TFBT-1 and 2.60 g g–1 for TFBT-2. The results of experimental analyses of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy clearly revealed that their high performance is attributed to the strong interactions between the adsorbed iodine and the uniformly located abundant nitrogen adsorption sites in the pores of the two COF materials, which are from both pre-introduced acylamides and in situ-generated Schiff base imine groups. The present work revealed that by introducing the nitrogen-rich sites into the frameworks of the COF materials, effective iodine adsorbents can be achieved.