Covalent Organic Frameworks Functionalized with Thioether or Vinyl Groups for Efficient and Rapid Capture of Multiple Iodine Pollutants
Efficient sequestration of radioactive iodine species (I2, CH3I, I3−) is vital for nuclear safety and environmental protection. However, developing multifunctional adsorbents that remain effective under diverse conditions remains a significant challenge. Herein, we report two functionalized PD-COFs (PD-WS and PD-WY) with moderate crystallinity, outstanding thermal stability, and robust chemical resistance. They exhibit superior adsorption performance in both gas and liquid phases. Specifically, at 75°C, PD-WY achieves capacities of 4.88 g g−1 for I2, 1.55 g g−1 for CH3I, and 5.55 g g−1 for the I2/CH3I mixture, while high capacities are also retained at room temperature. In solution, PD-WY adsorbs up to 3.56 g g−1 of I3− in water and 2.00 g g−1 of iodine in cyclohexane. These COFs display rapid kinetics (K80% = 3.25 g g−1 h−1 for I2 and 7.89 g g−1 h−1 for I3−) and excellent selectivity. Mechanistic studies indicated that the excellent iodine affinity of PD-COFs arises from their rich electronic structures, abundant active sites, and charge transfer interactions. These findings position PD-COFs as highly promising adsorbents for nuclear waste treatment and environmental remediation.