Constructing a magnetic ionic covalent organic polymer through a post-synthesis functionalization approach for efficient iodine/iodide adsorption†

The development of covalent organic polymers (COPs) to remove iodine in vapor and from solutions is highly desirable for the sustainable production of nuclear energy. Herein, we reported the successful synthesis of an ionic COP (iCOP) via a post-synthesis functionalization approach. Subsequently, a magnetically responsive iCOP (IMF-COP-Fe) was obtained using a simple double-solvent reduction method to facilitate separation. It is noteworthy that IMF-COP-Fe could rapidly achieve solid–liquid separation under the influence of an external magnetic field, with a magnetic recovery rate of 91.89%. The rational design endowed IMF-COP-Fe with affinity sites for removal of iodine in vapor and from solutions. Experimental findings demonstrated that the adsorption capacity of IMF-COP-Fe towards iodine vapor was 2.46 g g⁻¹ at 75 °C. Concurrently, the iodine removal rate of IMF-COP-Fe in 700 mg L⁻¹ iodine–cyclohexane solution reached 80.56%. Even after four adsorption–desorption experiments, it still maintained good adsorption performance. Furthermore, the maximum adsorption capacity of IMF-COP-Fe for iodide ions was found to be 109.9 mg g⁻¹. The present study proposes original concepts for the rational molecular design of materials for simultaneous removal of various forms of radioactive iodine.