Triptycene-based and imine linked porous uniform microspheres for efficient and reversible scavenging of iodine from various media: a systematic study

Abstract

The effective and efficient capture as well as storage of radioisotopes of iodine is of significant importance in the treatment of nuclear waste. Further, the use of radioisotopes of iodine in medical therapy requires proper capture of radioactive iodine. Thus, there is a pressing need to develop novel adsorbents obtained using easy and simple methods that can capture iodine from various media with good uptake capacity. With this target, a new triptycene-based porous organic network (TP_POP-7) was designed and synthesized using a flexible trialdehyde with a triazine core and a rigid three-dimensional triptycene triamine as monomers. The two trifunctional monomers were covalently linked using the Schiff base reaction. TP_POP-7 is a porous organic polymer with good thermal and chemical stability. Due to the presence of abundant electron rich arene rings and N centers in the polymeric framework, efficient interaction with iodine was anticipated. Indeed, TP_POP-7 proved to be a promising material for capturing iodine from various media/conditions such as iodine vapor at elevated temperature (75 °C: 4215 mg g⁻¹) and room temperature (25 °C: 2040 mg g⁻¹), iodide ions from aqueous solution (2312 mg g⁻¹) and molecular iodine from organic solution (865 mg g⁻¹). Further, TP_POP-7 is a recyclable adsorbent without much compromise in its capture performance. Considering the high iodine uptake values under different conditions with good retention capability, TP_POP-7 emerges as one of the best materials for reliable capture and storage of iodine.