Robust triazene-resorcinol polymeric framework for universal iodine and iodide scavenging

Abstract

Iodine and iodide capture from off-gas and contaminated solutions has remained an unmet challenge, which is vital for environmental protection and reducing hazards. The Polymer Organic Frameworks (POFs) based adsorptive separation is a promising method compared to the traditional one, which largely depends on using corrosive liquids. Herein, we report a hydrophobic polar framework (HPF-1) for iodine and methyl iodide (Me-I) sequestration with a moderate gas phase iodine uptake of 1.78 g/g at 80 °C and Me-I uptake of 0.93 g/g at 75 °C. Additionally, HPF-1 can capture iodine from aqueous and non-aqueous media with a high capacity of 0.59 g/g from iodine solution in n-hexane (concentration = 400 mg/L) and 2.165 g/g from a 3 mM aqueous solution of I2 and KI. Moreover, the material exhibits high chemical stability, easy recyclability, and can capture I2 even under humid conditions with only ∼8 % loss in capacity. XPS study of the I2 adsorbed HPF-1 displays the presence of both I2 and polyiodide species (I3– and I5–). Alternatively, XPS analysis of Me-I adsorbed HPF-1 shows the existence of iodide and quaternary N species. This indicates triazene-N to be a strong adsorption site for I2 and Me-I, which was further supported by DFT investigations.