Adsorption-induced chemical reaction for in situ immobilization of radioactive anions on pristine β-Bi2O3 microflowers

•β-Bi2O3 microflowers as ion adsorbents were prepared via a solvothermal method.•β-Bi2O3 showed high uptake capacity for SeO32- (571 mg/g) and I- (239.5 mg/g) ions.•β-Bi2O3 showed high selectivity for SeO32- and I- in the excessive competing ions.•Adsorption-induced chemical reaction mechanism of anions on β-Bi2O3 was explored.•The anti-leaching of the immobilized radioactive anions facilitated their disposal.