Synthesis and study of low-cost nitrogen-rich porous organic polyaminals for efficient adsorption of iodine and organic dye

Effective Iodine Adsorption by Nitrogen-Rich Nanoporous Covalent Organic Frameworks

“…The occurrences of the chemisorption in both COFs and the formation of polyiodide anions after adsorption were further confirmed by Raman spectroscopy. As shown in Figure g,h, compared with the original TFBT-1 and TFBT-2 , strong peaks at 106 and 165 cm –1 for I 2 @TFBT-1 and 111 and 173 cm –1 for I 2 @TFBT-2 attributed to the stretching vibrations of I 3 – and I 5 – anions, respectively, were observed. − ,− Consistent with the analysis results of XPS spectroscopy, the results of Raman spectroscopy also indicate that the N in the constructed two COFs undergoes electron transfer with iodine, proving that the chemisorption process takes place during the processes of iodine adsorption.…”

“…Then, their quantitative iodine-release capabilities were then calculated by the thermal heating methods. By heating the iodine-loaded COFs at 125 °C at ambient pressure, − ,− the weight-loss curves were obtained by measuring sample weights at different times. As shown in Figure d, initially, the iodine release curves of I 2 @TFBT-1 and I 2 @TFBT-2 showed a linear decreasing trend, with about 64.87 and 51.44% of iodine released rapidly within 70 min.…”

“…Recently, a class of organic polymeric porous materials with crystalline and periodic structures, that is, covalent organic frameworks (COFs), − have shown highly promising potential in the applications of heterogeneous catalysis, − chemical sensing, bio-imaging, , and photodynamic therapy, − proton conduction, and energy storage, − as well as adsorption and separation to kinds of ions and molecules, − including iodine. − Due to their inherent porosity and strong covalent bonding of the organic components with light elements such as C, H, O, and N, COF materials not only show low density and relatively high stability but also display chemical tenability. − For instance, functional organic moieties with photoresponsive activity, proton-transport properties, and even chiral centers have been introduced into the COFs during the syntheses of precursors or post-modification of the constructed frameworks for photocatalysis, − proton conduction, ,− and asymmetric catalysis, − respectively. Previous works on iodine adsorption revealed that by decorating the framework with nitrogen-rich groups, the adsorption capacity of iodine can be significantly improved. − Thus, introducing nitrogen-rich groups into the COFs should be a feasible way for the fabrication of effective iodine adsorbents.…”

Multi-Functionalization Integration into the Electrospun Nanofibers Exhibiting Effective Iodine Capture from Water

“…He and co-workers fabricated nitrogen-rich porous organic polyaminals by the condensation reaction from N-containing monomers. The N sites with high electron density offered the host–guest interactions making the polyaminals display a high iodine capture capacity of 3.58 g g –1 in the vapor phase . Azambre’s group impregnated branched polyethyleneimine into nanosilica adsorbents, and the results demonstrated that the adsorption iodine capacities depend on the N content of the samples .…”

“…The N sites with high electron density offered the host−guest interactions making the polyaminals display a high iodine capture capacity of 3.58 g g −1 in the vapor phase. 22 Azambre's group impregnated branched polyethyleneimine into nanosilica adsorbents, and the results demonstrated that the adsorption iodine capacities depend on the N content of the samples. 23 Additionally, studies showed that cationic adsorption sites could also promote the iodine adsorption to capture the formed polyiodide anions by Coulomb interactions.…”