Adsorption-Induced Phase Transition for in Situ Immobilization of Radioactive Anions on Pristine Β-Bi2o3 Microflowers

It is a great challenge to design absorbent materials with high adsorption capacity, selectivity and irreversibility for immobilizing radioactive anions from wastewater. Herein, pristine β-Bi2O3 microflowers are fabricated via a facile urea-assisted alcoholysis of bismuth nitrate pentahydrate. The material exhibits highly efficient adsorption ability of both selenite (SeO32-) and iodide (I-) with fast kinetics and high capacities. The maximum adsorption capacities are 488 mg/g for SeO32- and 231.6 mg/g for I-, which are much higher than those of most of the reported adsorbents. Furthermore, the adsorbents show excellent selectivity for both SeO32- and I- in the presence of largely excessive competitive anions, such as sulfate and nitrate, and can steadily work over a broad pH range from 4 to 11. The adsorbent presents excellent resistance for leaching the adsorbed ions into solution, thus exhibiting good practicability for the efficient removal of anions from the target anion-contaminated synthetic seawater. The excellent adsorption and stable chemical immobilization performance of anions is attributed micro/nanostructure of the β-Bi2O3 microflowers and their adsorption-induced phase transition. These findings would render pristine β-Bi2O3 promising for radioactive anion extraction and immobilization from wastewater for final disposal