Pyrazole-directed functionalization of activated collagen fiber for highly specific capture of iodine vapor

The highly specific capture of radioactive iodine vapor generated during spent fuel reprocessing exerts a pivotal influence on ensuring the sustainable development of nuclear energy. In this study, we successfully prepared pyrazole-directed functionalized leather waste collagen fiber composite (Pyrazole@ACF) by immobilizing pyrazole ring through Schiff base reaction on the alkaline-activated collagen fiber (ACF) interface. The peak capacity for capturing iodine vapor by Pyrazole@ACF is shown to be 3.494 g/g, which is markedly higher compared to that of ACF (0.928 g/g). Pyrazole@ACF was characterized using FE-SEM, FT-IR, and XPS, revealing the release of numerous active functional groups from ACF that facilitated iodine-induced capture and pyrazole ring immobilization. Furthermore, the interaction mechanism between functional groups and iodine was further elucidated through Density Functional Theory (DFT) calculations. The iodine capture effect of Pyrazole@ACF is primarily ascribed to the existence of active functional groups (C = O, –OH, and –NH2) on ACF, as well as the charge transfer occurring between the grafted pyrazole moieties and iodine, ultimately leading to the generation of I3− polyiodide complexes and subsequent iodine capture. Consequently, Pyrazole@ACF exhibits a strong specific capture capability for iodine vapor, along with excellent thermal stability and iodine immobilization properties, meeting the application requirements under practical conditions.