Ultrafast removal of ReO4-/TcO4- by radiation-induced grafting of imidazole ionic liquid on alkylated nano-silica microspheres

In this study, two different alkylated nano-silicas were synthesized from in-situ growth and post-modification method respectively, and the 1-vinyl-3-ethylimidazolium bromide ([C(2)VIm]Br) was grafted onto them by radiation-induced grafting technique to fabricate nano-silica based adsorbents for ReO4-/TcO4- removal. The charged imidazolium moieties were controllably immobilized onto the nano-size substates by adjusting the radiation dose and monomer concentration, and the resulting adsorbents (S(P)-Si-MPTS-IL) were characterized by FTIR, SEM, EA and TGA. Subsequently, their adsorption properties for ReO4- were systematically studied in batch adsorption experiments. Combining the advantages of both nano-silica and ionic liquid, the prepared adsorbents exhibited ultrafast uptake (within 1min), high selectivity, and good cyclic stability (5 cycles, 95% retention) against ReO4-. Besides, they showed excellent radiation resistance and the adsorption properties were basically unchanged after 1200 kGy. Finally, FTIR and XPS analysis confirmed that the mechanism of adsorption process was ion exchange. This study laid a foundation for the synthesis and application of novel nano-silica adsorbent for ReO4-/TcO4-.