Constructing multiple sites porous organic polymers for highly efficient and reversible adsorption of triiodide ion from water

The utilization of nuclear power will persist as a prominent energy source in the foreseeable future. However, it presents substantial challenges concerning waste disposal and the potential emission of untreated radioactive substances, such as radioactive ¹²⁹I and ¹³¹I. The transportation of radioactive iodine poses a significant threat to both the environment and human health. Nevertheless, effectively, rapidly removing iodine ion from water using porous adsorbents remains a crucial challenge. In this work, three kinds of multiple sites porous organic polymers (POPs, POP-1, POP-2, and POP-3) have been developed using a monomer pre-modification strategy for highly efficient and fast I₃⁻ absorption from water. It is found that the POPs exhibited exceptional performance in terms of I₃⁻ adsorption, achieving a top-performing adsorption capacity of 5.25 g g⁻¹ and the fastest average adsorption rate (K_80% = 4.25 g g⁻¹ h⁻¹) with POP-1. Moreover, POP-1 exhibited exceptional capacity for the removal of I₃⁻ from flowing aqueous solutions, with 95% removal efficiency observed even at 0.0005 mol L⁻¹. Such results indicate that this material has the potential to be utilized for the emergency preparation of potable water in areas contaminated with radioactive iodine. The adsorption process can be effectively characterized by the Freundlich model and the pseudo-second-order model. The exceptional I₃⁻ absorption capacity is primarily attributed to the incorporation of a substantial number of active adsorption sites, including bromine, carbonyl, and amide groups.